Abstract
The Bactrocera dorsalis species complex comprises major pests of various tropical fruit and vegetable crops. Populations typically increase during the rainy season, a period when pesticide applications are often less effective. Additionally, pupation in the soil further complicates control efforts. Streptomyces spp., entomopathogenic bacteria, show potential as biological agents against the pupal stage of fruit flies. This study aimed to evaluate the effects of S. fradiae strain JB-1 on pupal mortality, adult development type, and developmental time in soils of varying depths. The mean percentages of pupal mortality, successful imago, and abnormal imago differed significantly among soil treatments, whereas the mean percentage of normal imago did not. Similarly, significant differences in the mean percentages of dead pupae, successful imago, and normal imago were observed across soil depths, but no significant differences were found for abnormal imago. Application of S. fradiae extended the pupal stage duration across all imago parameters, while soil depth had no significant effect. These findings suggest that S. fradiae strain JB-1 is effective in controlling fruit fly pupae in soils of varying depths. This study provides a foundation for integrating entomopathogenic Streptomyces spp. into fruit fly control strategies targeting the pupal stage.
Supplementary Information
The online version contains supplementary material available at 10.1038/s41598-025-16518-z.
Keywords: Fruit flies, Soil moisture, Pupation, Soil depth, Pest control
Subject terms: Ecology, Zoology, Ecology
Introduction
Fruit flies belonging to the Tephritidae family are an important pest group in fruit and vegetable commodities1–4. Bactrocera is a large genus within the family Tephritidae, consisting of approximately 750 known species, primarily distributed across Southeast Asia, Australia, the Pacific region, and the Afrotropics. Among these, 79 closely related species are grouped under the Bactrocera dorsalis species complex with similar morphological characteristics of predominantly or entirely black scutum5. Collectively, the B. dorsalis species complex is responsible to cause severe damage to fruit crops in tropical regions, including Indonesia5–10. These pests attack various host plants, including mango (Mangifera indica L., Anacardiaceae), banana (Musa spp., Musaceae), star fruit (Averrhoa carambola L., Oxalidaceae), guava (Psidium guajava L., Myrtaceae), water apple (Syzygium aqueum), orange (Citrus spp., Rutaceae), sapodilla (Achras zapota (L.) P. Royen, Sapotaceae), papaya (Carica papaya L., Caricaceae), peach (Prunus persica (L.) Batsch, Rosaceae), jackfruit (Artocarpus heterophyllus), grape (Vitis spp., Vitaceae), pomegranate (Punica granatum L., Lythraceae), lychee (Litchi chinensis Sonn., Sapindaceae), and longan (Dimocarpus longan Lour., Sapindaceae)8–10. Usually, damaged fruits become hollow and rot quickly, posing a major risk to the fresh commodity trade due to the enforcement of strict quarantine restrictions11. The economic impact of B. dorsalis is substantial. In India, infestations reduce the marketable mango yields by 25–30%, with estimated losses of USD356 million annually across various crops such as guava, sapodilla, citrus, and mango12,13. Thailand experiences an annual mango yield loss of 15.5%14. In Africa, the annual yield loss exceeds USD2 billion15. Exports restriction of guava to the United States and Japan result an additional loss of USD2.5 million16. In Indonesia, infectious leads to losses between 25% and 50%, with some mango plantations experiencing up to 100%17.
Reports of significant economic losses caused by B. dorsalis species complex highlight the need for strengthen biosecurity measures and serve as a warning for existing fruit fly control programs. However, controlling B. dorsalis species complex is challenging due to its biological characteristics. The larvae are endophagous which makes them less susceptible to insecticide treatments. As a result, most control strategies target the adult stage. Commonly employed methods include synthetic pesticides, baiting systems using methyl eugenol, standard area wide pest management, Jackson traps, and sterile insect techniques18–21. However, the extensive use of insecticide such as beta-cypermethrin, cyhalothrin, malathion, and spinosad has led to the development of insecticide resistance not only in B. dorsalis (Hendel), but also in related species such as B. oleae (Rossi), Ceratitis capitata (Wiedemann), and Zeugodacus cucurbitae (Coquillett)22–25. In response to the growing concerns about pesticide resistance and residue limits in agricultural exports, research has increasingly focused on non-chemical pest control methods. Therefore, biological control using entomopathogenic microorganisms, such as fungi and bacteria, offers a promising alternative, particularly targeting the larval and pupal stages of Bactrocera spp26–30.
Among entomopathogenic fungi, species such as Metarhizium anisopliae (Metschnikoff) Sorokin, Metarhizium robertsii JF Bisch, SA Rehner & Humber, Isaria fumosorosea Wize, Glomus spp., Beauveria bassiana (Bals.-Criv.) Vuill., and B. brongniartii (Sacc.) Petch, have demonstrated the ability to infect fruit fly pupae and cause significant mortality29,32,33. Studies have shown that Beauveria bassiana and M. anisopliae can achieve pupal mortality rates of up to 50%34. These fungi infect their host by penetrating their mycelium through the larval or pupal cuticles31 and secreting enzymes such as chitinases, lipases, and proteases, which disrupt the insect’s physiological functions36–38. In a study, the use of contaminant attractant traps (ACTs) treated with M. anisopliae var. acridum and methyl eugenol showed increased fly contamination rates, reaching up to 99.67% with higher trap densities35. In addition to fungi, entomopathogenic bacteria also hold potential for pest control39,40. Notably, the genus Streptomyces, have shown efficacy against insect pests. Studies have demonstrated that Streptomyces narbonensis, S. spectabilis, and S. deserti, can cause up to 100% mortality in Bactrocera sp. larvae and pupae41. Another Streptomyces species, S. fradiae known for its production of chitinase42 may also possess insecticidal properties and thus warrant further investigation as a potential biological control agent. Moreover, S. fradiae strain NKZ-259 has been reported to promote tomato seedling growth, suggesting additional benefits for crop productivity43.
Targeting the pupal stage of fruit flies is a strategic approach, as it represents a period of insect dormancy. Many studies on the pupal stage focus on adult emergence rates (eclosion), developmental duration, and survival44–47. These factors are strongly influenced by environmental condition particularly soil properties such as temperature, humidity, and light conditions48–54. Although temperature has been extensively studied for its role in pupal development50–54other soil characteristics are often underexplored. Research has shown that pupation depth significantly affects emergence success46,47. Shallow pupation (0–4 cm) is common under high soil moisture conditions and generally results in higher emergence rate47. In contrast, emergence decreases significantly at depths greater than 20 cm46.
Despite the extensive research on fungal entomopathogens, there is limited information on the efficacy of Streptomyces spp., especially S. fradiae in controlling fruit flies across different soil depth. This gap in knowledge as particularly important, as soil depth directly influences pupal development and could affect the success of biological control agents. Therefore, the objective of this study is to evaluate the effect of S. fradiae on the mortality, developmental time and emergence characteristics of B. dorsalis species complex pupae across varying soil depth. By understanding how this bacterial species interacts with soil conditions and insect development, the study aims to contribute to the development of effective, environmentally sustainable pest management strategies for fruit fly control in agricultural systems.
Materials and methods
Larva collection and rearing
The larvae of B. dorsalis species complex were collected from damaged chili fruit at the Batu Sub-district, Batu City and Dau Sub-District, Malang District, East Java, which are located about 16 km from Malang City, East Java (Fig. 1). The larvae were collected from the chili fruit because those were easily collected. Samples of chili fruit attacked by fruit flies were collected from discarded chilies that had symptoms of damage, such as black dots on the base and wilted fruit. A total of 100 chilies were sampled which were then collected from the field and reared in the Laboratory of Animal Diversity and Environmental Technology, the Department of Biology, Universitas Brawijaya, Malang, Indonesia. Those chilies were placed in 10 small plastic boxes and lined with cloth at the bottom. The plastic boxes were inserted into a large plastic box filled with sterilized sand for the development of larvae. After 14 days, the large plastic box was opened, and the pupae were collected by sifting the sand. The pupae were placed on a transparent plastic vial until they hatch into adults. Adults were identified following the description in the key manual54,55. The characteristics of this species were described as follows, distinct dark on the facial spots; scutum on its thorax mostly or entirely black; lateral postsutural yellow vittae present; medial postsutural yellow vitta absent; wings transparent except the costal band which is confluent and overlaps with R2 + 3 and expands around the apex of R4 + 5; scutellum yellow with dark basal band and never with other dark patterns; abdomen with pale posterior band on medially undivided tergite II and terga III-V forming a dark ‘T’ pattern without dark lateral margins54,55. Referring to the key manual for adult fruit fly identification, samples from the B. dorsalis species complex were collected and reared for subsequent generations. Fifty pairs of newly emerged adults were housed in a 50 × 50 × 50 cm Plexiglas insect-rearing cage, provided daily with a 10% sucrose solution and protein hydrolysate.
Fig. 1.
Location of fruit fly larvae and soil sampling in Batu sub-district, Batu City and in Dau sub-district, Malang District, East Java, Indonesia.
The emerging/hatching fruit fly imago were fed with a 10% sucrose solution and protein hydrolysate. Sucrose was given routinely every day. A plastic cup with an oviposition hole (± 0.1 mm in diameter) at the top was placed inside the fruit fly cage to facilitate egg-laying by female imago. The female imago deposited eggs into the plastic cup, which were collected after two hours. The collected eggs were then transferred to a plastic bowl containing food (made of carrot puree (mixed with yeast, nipagin, distilled water and propionic acid)46. This bowl was subsequently placed inside a larger plastic box filled with sand, serving as a pupation medium. The F1 pupae were then collected and used for further experiments. The F1 pupae in the previous test showing the imago eclosion more than 90%. In subsequent studies, rearing up to F3 showed that the eclosion rate slightly decreased, indicating adaptation success in the earlier generation and a reduction in the following generation. Due to this situation, the use of the fruit flies from the field in early generation may affect the mortality in the experiment, this became the limitation of this study.
Soil media
The soil as media for experiments was collected from Batu Sub-regency, Batu Regency and Dau Sub-regency, Malang Regency, East Java. At each location, 20 kg of soil was sampled. The soil was collected from orange orchards (mixed with chili) from 0 to 20 cm depth of using a hoe. Soil from both locations were mixed. In the laboratory, the soil was air-dried for 96 h. Dried soils were pounded and sieved using a 2 mm mesh. Prior to the experiment, soil texture was analyzed to determine the soil texture and the result indicated that the soil was composed of sand (10%), clay (72%), and silt (18%), while soil moisture was 11%.
Streptomyces spp. microbes were isolated from four locations represented the location in East Java and remote areas in eastern (East Nusa Tenggara) dan western (Belitung) Indonesia. Two locations in East Java were a tomato garden in Pare, Kediri, East Java (Par isolate strain PA-1) and forested areas in Jember, East Java (Jem isolate strain JB-1). Microbes from East Nusa Tenggara was collected from dry land cultivation area in Dompu (Dom isolate strain DO-1); while that from Belitung Island (Bel isolate strain BE1) was collected from former coal mining land. The soil plating method was used for isolation, with 1 gram of soil from each site suspended in 9 ml of sterile distilled water and serially diluted up to 10⁻⁴. A 0.5 ml sample from the final dilution was cultured on inorganic salt starch agar (ISSA) in Petri dishes and incubated at 28 °C for four days to obtain a mixed culture.
After incubation, colonies of Streptomyces sp. were selected by isolating a single loop from each colony and culturing it on ISP-4 complex media in petri dishes. This process was repeated seven times to obtain pure Streptomyces isolates. Prior to treatment, the four isolates were tested for their ability to produce chitinase, all of which successfully demonstrated chitinase expression, except Dom isolate. Therefore, this isolate was excluded from further virulence test. Identification was conducted at the Indonesian Genetics Science Laboratory using 16 S rRNA DNA sequencing. The resulting sequences were analyzed using the Basic Local Alignment Search Tool (BLAST) from the Biology Workbench (SDSC).
Sequence analysis revealed that the Par and Jem isolates shared 1292 base pairs (bp) demonstrated 99.85% similarity with Streptomyces fradiae RSU15, Dom isolate exhibited 1334 bp, indicated 98.92% similarity to Streptomyces leeuwenhoekii WA12, while the Bel isolate indicated 1346 bp, showed 99.48% similarity to Streptomyces kunmingensis DSD1764. A bioassay was conducted using B. dorsalis species complex pupae per treatment to assess the virulence of the three Streptomyces isolates, with four replications. The results showed high pupal mortality rates of 90%, 100%, and 100% for the Par, Jem, and Bel isolates, respectively. Based on these findings, further analysis was conducted using the Jem isolate (S. fradiae), demonstrating the highest potential for fruit fly control.
Treatment
A day-old B. dorsalis species complex pupae were taken from the sand as pupation media. The experiment was conducted by placing pupae in soil media. The treatments consisted of dried soil, watered soil, and S. fradiae-treated soil. Treatment of dried soil represented a negative control (where Streptomyces fradiae was absent), while watered soil represented a positive control (where water was present). Prior to the experiment, the soil media was sterilized in an autoclave at 121 °C for 15 min. Watered soil treatment was conducted by adding 15% v/v of sterile distilled water mixed with soil. This water addition increases the soil moisture up to 30%. The concentration of water addition was done following the previous study63. In the previous study, optimum water concentration was achieved at 15% v/v, while more concentration led to clumped and hardened soil because this study used sieved soil.
S. fradiae-treated soil was carried out by mixing S. fradiae dilution with soil media at a concentration of 15% v/v. The soil level was treated using a tube made of transparent mica with a diameter of 5 cm. The mica plastic was attached to 20 × 20 cm of cardboard paper at the bottom. Approximately 10 cm of space was added at the top of the tube to ensure oxygen availability. Furthermore, the plastic tube was filled with 1 cm thick soil media. After that, the pupae were placed on the surface, and then the soil was poured into the tube according to the depth of each treatment. The top of the tube was covered with a layer of cotton cloth to prevent adult fruit flies from flying out. The treatments included eight soil levels: 0, 4, 10, 20, 30, 40, 50, and 60 cm depths45. Replication was carried out four times, where each replication was given 20 pupae aged 1–2 days. After six days, the pupal status of each treatment was checked every day until 16 days after treatment. The number of fruit flies released and their physical condition were observed. Fruit flies were classified based on the perfection of their abdomen and wings. Imago with deformed or deformed wings was considered abnormal. Regarding the use of animals, this study has received ethical approval from the institutional committee (Research and Community Development Institute, Universitas Brawijaya) that approved the experiments.
Data analysis
The number of adult fruit flies hatched (successful imago), and morphological normality of each treatment were calculated, and the results were presented as a percentage, while the length of development time was presented in days. Imago’s success was counted based on its emerging body. The unsuccessful imago was considered as dead pupae. The surviving imago was then classified into normal or abnormal based on its body characteristics. The normal imago showed flattened wings, a bright yellow body, and an inflated abdomen, while abnormal or deformed adult fruit flies showed the characteristics of wrinkled wings, a pale-yellow body, and a short, small abdomen47.
Statistical data analysis was conducted to compare the average percentage of dead pupa, successful imago, normal imago and abnormal imago between treatments and soil levels. Regression and correlation tests were conducted to analyze the relationship between those imago parameters and soil levels. Data normality analysis was carried out prior to statistical analysis. The normality test indicated that the data were not normally distributed, even though they had been transformed. Therefore, differences in mean dead pupa, successful imago, normal imago and abnormal imago between treatments and soil depth were analyzed using non-parametric analysis. In this regard, Kruskal – Wallis analysis was selected to show the mean difference among the treatments because it meets the requirements for a sample size of more than two groups, and sample members between groups were different. If the analysis results show significant differences, the Dunn’s post hoc test adjusted by Bonferroni correction was done to evaluate multiple pairwise comparisons. Furthermore, the correlation of the means of B. dorsalis successful imago, normal and abnormal was tested using a linear regression model. The data were calculated using the Excel program, while the statistical test was processed using PAST version 4.04, and differences between the means of observed parameter results were considered significant at p ≤ 0.05.
Results
The effect of soil treatments on the percentage of Imago parameters
To examine the influence of soil properties and the application of S. fradiae on mortality and adult development type, B. dorsalis species complex pupae were placed in different soil media, including watered soil, dried soil, and soil treated with S. fradiae. The treatment significantly affected dead pupae(χ2 = 6.868; p = 0.0308), successful imago (χ2 = 6.868; p = 0.0308) and abnormal imago (χ2 = 9.800; p = 0.0049) but had no significant effect on normal imago (p > 0.05) (Table 1). Post-hoc tests for those significant parameters showed a significant difference in the percentage of dead pupae, successful imago and abnormal imago among the treatments. The average percentage of dead pupae in the S. fradiae-treated soil was higher (81.41% ± 3.29) than in dried soil (76.09% + 4.34) and watered soil (57.03% ± 6.34). However, the difference in adult mortality between S. fradiae-treated soil and dried soil treatments was not statistically significant, whereas its difference with watered soil treatments was significant. Consequently, the percentage of successful imago in the S. fradiae-treated soil was lower (18.59% ± 3.29) compared to dried soil (23.91% ± 4.36) and watered soil (42.97% ± 6.34) treatments, with a significant difference equal to the effect on pupae death. The application of S. fradiae did not show a significant difference to normal imago (χ2 = 4.367, p = 0.104) but had a significant impact on abnormal imago (χ2 = 9.800, p = 0.0049). The mean percentage of abnormal imago in the S. fradiae-treated soil was the lowest (3.28% ± 0.80) compared to the dried (9.84% ± 1.67) and watered soil (11.72% ± 3.03) treatments, and the effect of this treatment was significant (χ2 = 9.8; p = 0.005) (Fig. 2). From the observations of fruit flies appearing on the surface of the soil on mica tubes, it was seen that there were deformed fruit flies. A normal fruit fly has fully developed wings, bright body color, and long abdomen. The two horizontal black lines and the longitudinal median line are barely visible (Fig. 3A). Abnormal fruit flies have pale-yellow body, small and deformed abdomen (Fig. 3B) or short wrinkled wings (Fig. 3C). Pre-treatment pupae usually have tough body (Fig. 3D). Dead pupae have flabby body and softened cuticula. Some pupae demonstrated broken cuticula (Fig. 3E).
Table 1.
The statistical result (Chi-square value and significance) of the effects of different treatments on the percentage of Imago parameters (dead pupa, successful Imago, normal Imago and abnormal Imago).
| Variables | Dead pupa | Successful imago | Normal imago | Abnormal imago |
|---|---|---|---|---|
| Chi-square value | 6.868 | 6.868 | 4.367 | 9.800 |
| Asymp. Sig. | 0.0308 | 0.0308 | 0.1040 | 0.0049 |
Fig. 2.
Comparison among three different treatments on the percentage of fruit fly imago parameters. The different letters (a, b) above the error bars indicate a significant difference between the means, ns = not significant.
Fig. 3.
Imago and pupae of B. dorsalis species complex, (A) normal imago, (B, C) abnormal imago, (D) pre-treatment pupae and (E) dead pupae.
The effect of soil level on the percentage of Imago parameters
The effect of soil level on the percentage of B. dorsalis species complex mortality and adult development type was evaluated by putting the pupae of the in different soil depths (0, 4, 10, 20, 30, 40, 50, and 60 cm). The effect of soil level was significant on dead pupae (χ2 = 42.98; p = 2.58 × 10−7), successful imago (χ2 = 42.98; p = 2.58 × 10−7), and normal imago (χ2 = 43.45; p = 1.34 × 10−4) but that was insignificant on abnormal imago (p < 0.05) (Table 2). The mean percentage of dead pupae ranged from 35 to 94.58%. The lowest dead pupae percentage occurred at a depth of 4 cm (35% ± 8.00), while the highest was at 40 cm (94.58% ± 2.07). The percentage of survived imago ranged from 5.42 to 65%. The lowest percentage of living imago occurred at a depth of 40 cm (5.42 ± 2.17%), while the highest was at 4 cm (65.00% ± 8.00). The normal survived imago ranged from 2.92 to 55.00%. The lowest percentage of normal imago occurred at a depth of 40 cm (2.92% ± 1.56), while the highest was at 4 cm depth (55.00% ± 8.51). The percentage of abnormal imago ranged from 2.08 to 18.75%. The lowest percentage of abnormal imago occurred at a depth of 40 cm (2.08% ± 1.14), while the highest was at 0 depth (18.75% ± 7.13) (Table 3).
Table 2.
The statistical result (Chi-square value and significance) of the effects of different soil levels on the percentage of Imago parameters (dead pupae, successful Imago, normal Imago and abnormal Imago).
| Variables | Dead pupae | Successful imago | Normal imago | Abnormal imago |
|---|---|---|---|---|
| Chi-square value | 42.98 | 42.98 | 43.45 | 11.37 |
| Asymp. Sig. | 2.58 × 10−7 | 2.58 × 10−7 | 1.34 × 10−4 | 0.09033 |
Table 3.
The mean percentage (± SE) of dead pupa, successful Imago, normal and abnormal Imago across various soil depths (0, 4, 10, 20, 30, 40, 50, and 60 cm).
| Level (cm) | Dead pupae (%) | Successful imago (%) | Normal imago (%) | Abnormal imago (%) |
|---|---|---|---|---|
| 0 | 55.83 ± 8.18abc | 44.17 ± 8.18 cd | 25.42 ± 5.31 cd | 18.75 ± 7.13ns |
| 4 | 35.00 ± 8.00a | 65.00 ± 8.00d | 55.00 ± 8.51d | 10.00 ± 2.89ns |
| 10 | 52.50 ± 10.25ab | 47.50 ± 10.25 cd | 40.00 ± 10.57 cd | 7.50 ± 2.34ns |
| 20 | 87.92 ± 2.98d | 12.08 ± 2.98ab | 5.42 ± 1.68ab | 6.67 ± 2.41ns |
| 30 | 75.83 ± 5.90bc | 24.17 ± 5.90bc | 19.17 ± 5.14bc | 5.00 ± 1.38ns |
| 40 | 94.58 ± 2.17d | 5.42 ± 2.17a | 2.92 ± 1.56a | 2.08 ± 1.14ns |
| 50 | 79.58 ± 5.13 cd | 20.42 ± 5.13abc | 9.17 ± 3.36ab | 11.25 ± 2.96ns |
| 60 | 90.83 ± 2.81d | 9.17 ± 2.81ab | 4.17 ± 2.12a | 5.00 ± 1.95ns |
Note: Different letters on the same column indicate significant differences at the level of P < 0.05 Dunn Post hoc Test.
The percentage of dead pupae for all treatments formed a positive relationship with soil level (Fig. 4A), while that of successful imago formed a negative relationship with soil level (Fig. 4B). The relationship that occurred among those imago parameters was significant, except for the S. fradiae-treated soil (Table 4). In this treatment, the regression line that was formed tended to be flat, because it had a low slope (0.2968 for dead pupa and − 0.2968 for successful imago). The results showed that pupae death in the S. fradiae-treated soil was not affected by soil depth. The percentage of normal imago for all treatments formed a negative relationship with soil level (Fig. 4C). The relationship between normal imago and soil level for all treatments was insignificant (Table 4). The percentage of abnormal imago for the S. fradiae-treated soil formed a positive relationship with soil level, while other treatments formed a negative relationship (Fig. 4D). The relationship between abnormal imago and soil level for all treatments was significant except for the water treatment (Table 4). This showed that the percentage of abnormal imago in the S. fradiae and dried soil treatments was influenced by soil level.
Fig. 4.
Correlation between the means of fruit fly imago parameters: dead pupae (A), sucessful imago (B), normal imago (C) and abnormal imago (D) with soil treatments.
Table 4.
Correlation and significance of the effect of different soil levels on Imago parameters (dead pupa, successful Imago, normal Imago and abnormal Imago).
| Statistical value and significance | Dried soil | Watered soil | S. fradiae-treated soil |
|---|---|---|---|
| Dead pupa | |||
| Correlation (r-value) | 0.76905 | 0.73559 | 0.52991 |
| t-value | 2.9471 | 2.66 | 1.531 |
| p-value | 0.025709 | 0.037534 | 0.17675 |
| Successful imago | |||
| Correlation (r-value) | −0.76905 | −0.73559 | 0.52991 |
| t-value | −2.9471 | −2.66 | −1.531 |
| p-value | 0.025709 | 0.037534 | 0.17675 |
| Normal imago | |||
| Correlation (r-value) | −0.69732 | −0.60049 | −0.64387 |
| t-value | −2.383 | −1.839 | −2.061 |
| p-value | 0.054542 | 0.11546 | 0.084909 |
| Abnormal imago | |||
| Correlation (r-value) | −0.75828 | −0.33367 | 0.86736 |
| t-value | −2.849 | −0.867 | 4.269 |
| p-value | 0.029217 | 0.41926 | 0.0052684 |
The effect of soil treatments on the development time of Imago parameters
To examine the influence of soil properties and the application of S. fradiae on imago development, pupae of the B. dorsalis species complex were placed in different soil media, including watered soil, dried soil, and S. fradiae-treated soil. This study indicated the effect of soil treatments on fruit fly imago parameters. The effect was significant on the mean development time of successful imago (χ2 = 46.22; p = 6.68 × 10−8), normal imago (χ2 = 31.56; p = 1.18 × 10−4) and abnormal imago (χ2 = 35.78; p = 1.35 × 10−5) (Table 5). In general, the application of S. fradiae extended the development time of all imago parameters. The mean development time of successful imago in the S. fradiae-treated soil was significantly longer (13.72 days ± 0.34) compared to dried soil (11.33 days ± 0.66) and water treatments (7.62 days ± 0.30). The mean of development time of normal imago in S. fradiae-treated soil was also significantly longer (13.49 days ± 0.38) compared to dried soil (10.65 days ± 0.71) and water treatment (8.25 days ± 0.39). The mean development time of abnormal imago in S. fradiae-treated soil was higher than in dried soil and water, but the difference with water treatment was insignificant (Fig. 5).
Table 5.
The statistical result (Chi-square value and significance) of the effects of different treatments on the development time of Imago parameters (successful Imago, normal Imago and abnormal Imago).
| Variables | Successful imago | Normal imago | Abnormal imago |
|---|---|---|---|
| Chi-square value | 46.22 | 31.56 | 35.78 |
| Asymp. Sig. | 6.68 × 10−8 | 1.18 × 10−4 | 1.35 × 10−5 |
Fig. 5.
The effect of different treatments on the development time of imago parameters. The different letters (a, b,c) above the error bars indicate significant differences between the means (Dunn Post-hoc Test).
The effect of soil level on the development time of Imago parameters
The effect of soil level on the development time of B. dorsalis species complex was evaluated by putting the pupae of the in different soil depths (0, 4, 10, 20, 30, 40, 50, and 60 cm). Result showed that there was no difference in the means of development time of successful imago (p > 0.05), normal imago (p > 0.05) and abnormal imago (p > 0.05) at various soil levels (Table 6). The mean development time of successful imago ranged from 8.32 to 12.08 days. The longest development time occurred at a depth of 40 cm, while the fastest was at a depth of 0 cm. The mean development time of normal imago ranged from 8.92 to 13.13 days. The longest development time occurred at a depth of 40 cm, while the fastest was at a depth of 4 cm. The mean development time of abnormal imago ranged from 9.46 to 12.00 days. The longest development time occurred at a depth of 10 cm while the fastest was at 4 cm depth (Table 7).
Table 6.
The statistical result (Chi-square value and significance) of effects of soil level on the development time of Imago parameters (Dead pupa, successful Imago, normal Imago and abnormal Imago).
| Variables | Successful imago | Normal imago | Abnormal imago |
|---|---|---|---|
| Chi-square value | 8.54 | 9.76 | 2.33 |
| Asymp. Sig. | 0.27 | 0.20 | 0.94 |
Table 7.
The mean development time (± SE) of succesful, normal and abnormal Imago across various soil depths (0, 4, 10, 20, 30, 40, 50, and 60 cm).
| Level (cm) | Successful imago (%) | Normal imago (%) | Abnormal imago (%) |
|---|---|---|---|
| 0 | 8.32 ± 0.39 | 11.75 ± 0.54 | 10.79 ± 1.33 |
| 4 | 8.82 ± 0.72 | 8.92 ± 0.85 | 9.46 ± 0.75 |
| 10 | 11.05 ± 0.68 | 11.08 ± 0.84 | 12.00 ± 0.44 |
| 20 | 11.62 ± 1.34 | 10.78 ± 1.38 | 11.65 ± 1.48 |
| 30 | 11.38 ± 1.16 | 11.69 ± 1.03 | 10.61 ± 1.13 |
| 40 | 12.08 ± 2.09 | 13.13 ± 2.29 | 12.00 ± 3.00 |
| 50 | 11.51 ± 1.35 | 10.38 ± 1.43 | 11.17 ± 1.67 |
| 60 | 10.81 ± 1.77 | 9.47 ± 1.92 | 10.30 ± 2.15 |
Discussion
The soil treatments exerted substantially different effects on the percentages of dead pupae, successful imago, and abnormal imago. The percentage of dead pupae in the S. fradiae and dried soil treatments was greater than 75%, with no significant difference from those in the two other treatments. Meanwhile, the percentage of dead pupae in the water treatment was lower than 60%, which significantly differed from those in the two other treatments (Fig. 1). The high pupae mortality in the dried soil treatment may be related to low soil moisture levels. By contrast, the addition of water into soil media increased imago survival because it improved soil moisture. The dried soil has a water content of 11%, whereas the watered soil has a water content of 30%. With equal soil moisture as the watered soil treatment, S. fradiae application increased pupal mortality. This result indicates that S. fradiae treatment effectively reduces imago survival at 30% soil moisture conditions. The application of an entomopathogenic bacterium requires optimal environmental conditions. This condition matches the preconditions required for optimal development of fruit fly larvae and pupae.
Soil water content, pupal media, and other determinants influence pupal mortality by bacterial activities. Soil moisture and texture are key factors determining the success or failure of entomopathogen application48,56. These two factors interact in a complex relationship that involves the size and behavioral movement of the insect. Previous studies on pupation in B. dorsalis larvae showed that pupae develop optimally at 10–60% humidity. At a depth of 0–2 cm, 45.8% and 83.3% of fruit fly larvae pupate at 10% and 30% soil moisture, respectively48. The differences in survival rates between treatments may be ascribed to low soil water content, physical characteristics of the soil, and application of entomopathogens.
Soil texture, particularly the size distribution of pore spaces, affects the infectivity of spores, such as those of Beauveria bassiana, by mediating physical contact57. In this process, the physical properties of the soil alter as the pore size increases and the bulk density decreases. Physical and chemical characteristics of the soil, such as interstitial space, grain size, compaction, water content, and organic matter content, can affect the emergence of adult fruit flies on the soil surface. The success of fruit fly larval pupation increases in soil with large soil particles because adult fruit flies can quickly emerge from the pupa. Several soil properties, such as porosity and total organic matter, can reduce soil density and make it easier for fruit flies to emerge48. Soil texture can also cause abnormalities in adult fruit flies, such as in the wings and abdomen. Wing growth is imperfect and appears wrinkled or shriveled, and some flies have swollen abdomens. By contrast, fine soil has low porosity and may clump when exposed to water. As a result, the imago has difficulty exiting the pupae and emerging to the soil surface. These properties prevent emerging adult fruit flies from moving upward to reach the surface. In denser soils, adult fruit flies struggle to reach the surface due to the reduced total soil porosity57.
In the present study, soil depth significantly affected the mean percentages of dead pupae, successful imago, and normal imago, but not that of abnormal imago. Further tests revealed that the correlation with the percentage of dead pupae varied across treatments; in the dried soil and watered soil treatments, the percentage of dead pupae was significantly positively correlated, whereas no significant correlation was found in the S. fradiae treatment. Therefore, soil depth factor also influenced high mortality in the water treatment. In this treatment, the mortality rate increased at under the 10 cm depth. Similarly, in the water treatment, the pupal mortality rate was low at depths of 4–10 cm and increased sharply at depths of more than 20 cm. Conversely, the S. fradiae treatment had better consistency, with the graph formed having a low slope (Fig. 4A). At depths of 0–35 cm, this treatment also suppressed pupal mortality to more than 70%, whereas the other treatments showed a much lower pupal mortality. The results of this study align with those of previous studies that soil depth affects the survival of fruit fly imago46,47. In particular, soil depth exerts a significant negative effect on adult emergence of hybrids between B. dorsalis and B. carambolae. The emergence rate decreases with increasing soil depth. Higher survival rates of imago were observed at depths of 4 cm (95% ± 1.91) and 10 cm (86% ± 2.58)46. Similar results were observed in B. dorsalis treated with dried soil at several soil levels. The results suggest that soil depth significantly negatively affects the survival of B. dorsalis pupae. Higher survival rates of imago were observed at depths of 0 cm (60% ± 5.89) and 4 cm (58% ± 6.22)47.
Streptomyces fradiae treatment significantly affected the mean development time of successful and normal imago, but not that of abnormal imago. Development time was shortest across all imago parameters in the water treatment, likely due to higher humidity supporting pupal development. Although the percentage of normal pupae also increased under this treatment, the difference was not statistically significant. In contrast, pupal development was prolonged in the dried soil treatment, likely due to low moisture. The fastest development into imago occurred at a depth of 0 cm, while depths greater than 10 cm showed more variable development times, possibly because fewer adults successfully emerged. Only fully emerged adults were classified as successful.
Streptomyces fradiae affected the mean duration of the pupal stage and emergence of normal adults, likely by inhibiting pupal development and thereby slowing the overall process. As entomopathogenic bacteria, Streptomyces spp. are as promising biological agents due to their ability to produce secondary metabolites toxic to insect larvae and pupae42,58. For example, metabolites from S. hydrogenans at 1,600 µg/mL can caused 70% larval, 66.66% prepupal and 100% pupal mortality in S. litura59. Other species produce AP-123, a compound that suppresses development in Helicoverpa armigera and Spodoptera litura larvae by over 50%60. Streptomyces sp. strain ES2 (EMCC2291) synthesizes metabolites from 15 chemical classes, that significantly reduce α- and β-esterase activity in Spodoptera littoralis larvae. In this study, S. fradiae and S. kunmingensis can produce chitinase, which has shown up to 100% efficacy against fruit fly larvae and pupae in vitro. S. fradiae is also known to have ability to produce lipase and protese61,62. Another species, Streptomyces avermitilis may also produce emamectin benzoate, a compound highly toxic to Lepidoptera63 and capable of rapidly kill S. littoralis64.
Soil depth did not affect imago development time, and pupal development remained stable at > 10 cm depth. The duration of pupation time ranged from 8.82 to 12.10 days. This duration is similar to those in previous studies but differs from the result of this study. In other studies, pupal development time significantly differs at different soil levels46,47. Previous studies reported that soil depth influences the duration of pupal development of hybrids between B. dorsalis and B. carambolae. The mean development time ranges from 8.88 to 10.63 days. It is relatively stable at a depth of 4–40 cm and dramatically longer at 50 and 60 cm46. Previous studies also showed that the average pupal duration stage ranges from 8.01 to 12.78 days. Therefore, soil depth treatment significantly affects development time. The difference in this study may be attributed to the trend development time increasing from 10 to 40 cm, and then decreasing to 60 cm. It is also caused by quite extreme fluctuations that occur in the dried soil treatment. In this treatment, the development time increased from 4 to 10 cm in depth, decreased at 30 and 40 cm, increased again at 50 cm, and then decreased at 60 cm47.
The findings of this study highlight the Streptomyces fradiae (strain JB-1) as a promising biological control agent for fruit fly pupae across a range of soil depths, supporting its integration into pest management strategies targeting the pupal stage. This strain demonstrated more than 70% pupal mortality at soil depths of 0–35 cm. Its efficacy was not significantly affected by soil depth, indicating consistent performance. For optimal results, application should coincide with peak fruit infestation, typically marked by increased fruit drop due to larval feeding.
Conclusion
This study demonstrated that soil treatment substantially affected pupal mortality and the percentages of successful, abnormal, and dead adults. Soil level also notably affected pupal mortality and adult emergence, but did not influence imago abnormality. The difference in pupal mortality between S. fradiae and dried soil treatments was not statistically significant, whereas its difference with watered soil treatments was significant. A correlation was observed between soil level and pupal mortality in dried and watered soil treatments. However, no such correlation was found in S. fradiae treatments, suggesting that its efficacy was unaffected by soil depth. Additionally, S. fradiae-traeted soil significantly extended the pupal stage across all adult emergence parameters, whereas soil level had no such effect. These findings highlight S. fradiae strain JB-1 as a promising biological control agent for fruit fly pupae across various soil depths, supporting its integration into pest management strategies targeting the pupal stage.
Supplementary Information
Below is the link to the electronic supplementary material.
Acknowledgements
The authors thank the Rector and the Head of Research and Community Empowerment Institute, Brawijaya University.
Author contributions
The conception and design (ASL, AR), data collection (ASL, TT, AZ), data analysis (IF, AZ), interpretation of the data (ASL, BY, MI); the drafting of the paper (AR, AZ), revising it critically for intellectual content (SAA, AZ); and the final approval of the version to be published (ASL). All authors agree to be accountable for all aspects of the work.
Data availability
The authors confirm that the data supporting the findings of this study are available within the article [and/or] its supplementary materials.
Declarations
Competing interests
The authors declare no competing interests.
Footnotes
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
References
- 1.Manrakhan, A. Pre-harvest management of the Oriental fruit fly. CABI Rev.15, 1–13. 10.1079/pavsnnr202015003 (2020). [Google Scholar]
- 2.Jaleel, W. et al. Using two-sex life table traits to assess the fruit preference and fitness of Bactrocera dorsalis (Diptera: Tephritidae). J. Econ. Entomol.111, 2936–2945. 10.1093/jee/toy243 (2018). [DOI] [PubMed] [Google Scholar]
- 3.Vargas, R. I., Piñero, J. C. & Leblanc, L. An overview of pest species of Bactrocera fruit flies (Diptera: Tephritidae) and the integration of biopesticides with other biological approaches for their management with a focus on the Pacific region. Insects6, 297–318. 10.3390/insects6020297 (2015). [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Vayssières, J. F. et al. Seasonal abundance of Mango fruit flies (Diptera: Tephritidae) and ecological implications for their management in Mango and cashew orchards in Benin (Centre & North). J. Econ. Entomol.108, 2213–2230 (2015). 10. 1093/ jee/tov143. [DOI] [PubMed] [Google Scholar]
- 5.Drew, R. A. I. & Hancock, D. L. Biogeography, speciation and taxonomy within the genus Bactrocera Macquart with application to the Bactrocera dorsalis (Hendel) complex of fruit flies (Diptera: tephritidae: Dacinae). Zootaxa5190, 333–360. 10.11646/zootaxa.5190.3.2 (2022). [DOI] [PubMed] [Google Scholar]
- 6.Aluja, M., Ovruski, S. M., Garcia, M., Hurtado, F. R. & Enkerlin, W. M. Fruit fly (Tephritidae) management in the Neotropical region: history, state of the art, and perspectives. In Management Fruit Flies Americas, 11–66 (2024).
- 7.Hossain, M. S. et al. Comparison of biorational management approaches against Mango fruit fly (Bactrocera dorsalis Hendel) in Bangladesh. Crop Prot.135, 104807. 10.1016/j.cropro.2019.05.001 (2020). [Google Scholar]
- 8.Suputa, S., Trisyono, Y. A., Martono, E. & Siwi, S. S. Update on the host range of different species of fruit flies in Indonesia. Jurnal Perlindungan Tanaman Indonesia. 16 (2), 62–75. 10.22146/jpti.11725 (2010). [Google Scholar]
- 9.Mutamiswa, R., Nyamukondiwa, C., Chikowore, G. & Chidawanyika, F. Overview of Oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) in africa: from invasion, bio-ecology to sustainable management. Crop Prot.141, 105492. 10.1016/j.cropro.2020.105492 (2021). [Google Scholar]
- 10.Zhu, Y. et al. Use of age-stage, two-sex life table to compare the fitness of Bactrocera dorsalis (Diptera: Tephritidae) on Northern and Southern host fruits in China. Insects13, 258. 10.1093/jee/toy243 (2022). [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.He, Y., Xu, Y., Chen, X. & Biology Ecology and management of tephritid fruit flies in china: A review. Insects14, 196. 10.3390/insects14020196 (2023). [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12.Bana, J. K., Sharma, H., Kumar, S. & Singh, P. Impact of weather parameters on population dynamics of Oriental fruit fly, bactrocera dorsalis (Hendel)(Diptera: Tephritidae) under South Gujarat Mango ecosystem. JAM19 (1), 78–80. 10.54386/jam.v19i1.762 (2017). [Google Scholar]
- 13.Jitendra, M., Sandeep, S., Akilesh, T. & Chaube, M. Population dynamics of Oriental fruit fly, Bactrocera dorsalis (Hendel) in relation to abiotic factors. HortFlora Res. Spectr.1, 187–189 (2012). [Google Scholar]
- 14.Orankanok, W. Chinvinijkul, S., Thanaphum, S., Sitilob P. & Enkerlin W. R. Area-wide integrated control of oriental fruit fly Bactrocera dorsalis and guava fruit fly Bactrocera correcta in Thailand. In Area-Wide Control of Insect Pests, 517–526. (2007). 10.1007/978-1-4020-6059-5_48
- 15.Korir, J. K. et al. Grower adoption of an integrated pest management package for management of mango-infesting fruit flies (Diptera: Tephritidae) in embu, Kenya. Int. J Trop. Insect Sci. 35, 80–89. 10.1017/S1742758415000077 (2015). [Google Scholar]
- 16.Coates, B. S. et al. Arthropod genomics research in the united States department of Agriculture-Agricultural research service: current impacts and future prospects. Trends Entomol.11, 12–27 (2015). [Google Scholar]
- 17.Susanto, A. et al. The abundance of fruit flies (Bactrocera spp.) on some varieties of Mango from three selling sources. Int. J. Fruit Sci.22 (1), 110–120. 10.1080/15538362.2021.2023934 (2022). [Google Scholar]
- 18.Smith, P. H. Behavioral partitioning of the day and circadian rhythmicity. In World Crop Pests. Vol. 3(B). Fruit Flies: Their Biology, Natural Enemies and Control (eds Robinson, A. S. & Hooper, G.) 325–341 (1989).
- 19.Vargas, R. I. et al. Evaluation of Methyl Eugenol and cue-lure traps with solid lure and insecticide dispensers for fruit fly monitoring and male annihilation in the Hawaii areawide pest management program. J. Econ. Entomol.103, 409–415. 10.1603/EC09299 (2010). [DOI] [PubMed] [Google Scholar]
- 20.Sutantawong, M., Orankanok, W., Enkerlin, W. R., Wornoayporn, V. & Caceres C. The sterile insect technique for control of the oriental fruit fly, Bactrocera dorsalis (Hendel) in mango orchards of Ratchaburi Province, Thailand. In Proceedings of the 6th International Symposium on Fruit Flies of Economic Importance. Barnes, B. N. (Ed.). Isteg Scientific Publications. Irene, South Africa, pp. 223–232 (2004).
- 21.Pogue, T., Malod, K. & Weldon, C. W. Effects of semiochemical pre-feeding, physiological state, and weather on the response of Bactrocera dorsalis to Methyl Eugenol baited traps. Crop Protec. 188, 107015. 10.1016/j.cropro.2024.107015 (2025). [Google Scholar]
- 22.Kampouraki, A. et al. Recent evolution and operational impact of insecticide resistance in Olive fruit fly Bactrocera Oleae populations from Greece. J. Pest Sci.91, 1429–1439. 10.1007/s10340-018-1007-8 (2018). [Google Scholar]
- 23.Li et al. Dynamics of Bactrocera dorsalis resistance to seven insecticides in South China. Insects15 (9), 679. 10.3390/insects15090679 (2024). [DOI] [PMC free article] [PubMed] [Google Scholar]
- 24.Guillem-Amat, A. et al. Functional characterization and fitness cost of spinosad-resistant alleles in Ceratitis capitata. J. Pest Sci.93, 1043–1058. 10.1007/s10340-020-01205-x (2020). [Google Scholar]
- 25.Marchioro, C. A. Global potential distribution of Bactrocera carambolae and the risks for fruit production in Brazil. PLoS One. 11, e0166142. 10.1371/journal.pone.0166142 (2016). [DOI] [PMC free article] [PubMed] [Google Scholar]
- 26.Murtaza, G. et al. Biological control potential of entomopathogenic fungal strains against peach fruit fly, Bactrocera zonata (Saunders)(Diptera: Tephritidae). Peer J.10, e13316. 10.7717/peerj.13316 (2022). [DOI] [PMC free article] [PubMed] [Google Scholar]
- 27.Susanto, A. et al. Population dynamics and projections of fruit flies Bactrocera dorsalis and B. carambolae in Indonesian Mango plantation. ANRES56, 169–179. 10.34044/j.anres.2021.56.1.16 (2022). [Google Scholar]
- 28.Shaurub, E. S. H. Review of entomopathogenic fungi and nematodes as biological control agents of tephritid fruit flies: current status and a future vision. Entomol. Exp. Appl.171 (1), 17–34. 10.1111/eea.13244 (2023). [Google Scholar]
- 29.Prince, M., McKinnon, A. C., Leemon, D., Sawbridge, T. & Cunningham, J. P. Metarhizium spp. Isolates effective against Queensland fruit fly juvenile life stages in soil. PloS One. 19 (1), e0297341. 10.1371/journal.pone.0297341 (2024). [DOI] [PMC free article] [PubMed] [Google Scholar]
- 30.Hussein, M. A., Khaled, A. S., Ibrahim, A. A., Soliman, N. A. & Attia, S. H. Evaluation of entomopathogenic fungi, Beauveria Bassiana and Metarhizium anisopliae on peach fruit fly, Bactrocera zonata (Saunders) (Diptera: Tephritidae). EAJBSF10 (1), 59–68 (2018). [Google Scholar]
- 31.Soliman, N. A., Al-Amin, S. M., Mesbah, A. E., Ibrahim, A. M. & Mahmoud, A. M. Pathogenicity of three entomopathogenic fungi against the mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae). Egypt. J. Biol. Pest Control. 30, 1–8. 10.1186/s41938-020-00235-y (2020). [Google Scholar]
- 32.Gava, C. A. T., Tavares, P. F. D. S., Gonçalves, J. S. & Paranhos, B. A. J. Applying local entomopathogenic fungi strains to the soil can control Ceratitis capitata (Diptera: Tephritidae) Wiedemann adults. Biocontrol Sci. Tech.30 (2), 103–115. 10.1080/09583157.2019.1691716 (2020). [Google Scholar]
- 33.Wang, D. et al. Susceptibility of Oriental fruit fly, Bactrocera dorsalis (Diptera: Tephritidae) pupae to entomopathogenic fungi. Appl. Entomol. Zoolog. 56, 269–275. 10.1007/s13355-021-00734-w (2021). [Google Scholar]
- 34.Tora, M. & Azerefegn, F. Virulence of Beauveria Bassiana and Metarhizium anisopliae isolates against the Oriental fruit fly Bactrocera dorsalis (Diptera: Tephritidae) Hendel under laboratory conditions. Ethiop. J. Agric. Sci.31 (3), 53–67 (2021). [Google Scholar]
- 35.Faye, P. D. et al. Field efficacy of Metarhizium acridum (Hypocreales: Clavicipitaceae) in the control of Bactrocera dorsalis (Diptera: Tephritidae) in citrus orchards in Senegal. Int. J. Trop. Insect Sci.41, 1185–1195. 10.1007/s42690-020-00306-5 (2021). [Google Scholar]
- 36.Oktariana, P., Rosa, E., Setiawan, W. A. & Nurcahyani, N. The effectiveness of Nigrospora Sp. and Penicillium Sp. As entomopathogenic fungi against in Bactrocera Sp. J-BEKH11 (1), 33–40. 10.23960/jbekh.v11i1.361 (2024). [Google Scholar]
- 37.Ferreira, J. M. & de Soares, F. Entomopathogenic fungi hydrolytic enzymes: a new approach to biocontrol? J. Nat. Pest Res.3, 100020. 10.1016/j.napere.2023.100020 (2023). [Google Scholar]
- 38.Petrisor, C. & Stoian, G. The role of hydrolytic enzymes produced by entomopathogenic fungi in pathogenesis of insects: mini review. RJPP10, 66–72 (2017). [Google Scholar]
- 39.Rahmadhini, N., Mujoko, T., Nurfitriana, I. & Suryaminarsih, P. Potential secondary metabolites of Streptomyces sp. and Trichoderma sp. in suppressing the percentage of Spodoptera Litura attacks on corn plants. J. Exp. Agri Int.44 (12), 13–20. 10.9734/JEAI/2022/v44i122073 (2022). [Google Scholar]
- 40.Wicaksono, F. E., Windriyanti, W. & Suryaminarsih, P. Potential of Streptomyces spp. From peanut plant soil as an entomopathogen of pests Spodoptera Litura. Demeter: J. Farm. Agric.2 (1), 104–110. 10.58905/demeter.v2i1.290 (2024). [Google Scholar]
- 41.Suryaminarsih, P., Harijani, W. S., Muljani, I. R., Mindari, W. & Rahmadhini, N. Screening and identification of actinomycetes produced chitinolytic from suppression soil as biological agents of fruit flies (Bactrocera sp). Biosciences14 (1), 977–982 (2020). [Google Scholar]
- 42.Apichaisataienchote, B., Altenbuchner, J. & Buchenauer, H. Isolation and identification of Streptomyces fradiae SU-1 from Thailand and protoplast transformation with the chitinase B gene from Nocardiopsis prasina OPC-131. Curr. Microbiol.51, 116–121. 10.1007/s00284-005-4402-3 (2005). [DOI] [PubMed] [Google Scholar]
- 43.Myo, E. M. et al. Indole-3-acetic acid production by Streptomyces fradiae NKZ-259 and its formulation to enhance plant growth. BMC Microbiol.19, 155. 10.1186/s12866-019-1528-1 (2019). [DOI] [PMC free article] [PubMed] [Google Scholar]
- 44.Jing, T. X., Zhang, Y. X., Dou, W., Jiang, X. Y. & Wang, J. J. First insights into the intrapuparial development of Bactrocera dorsalis (Hendel): Application in predicting emergence time for tephritidae fly control. Insects10, 283. 10.3390/insects10090283 (2019). [DOI] [PMC free article] [PubMed] [Google Scholar]
- 45.Lin, J. et al. Quantification and impact of cold storage and heat exposure on mass rearing program of Bactrocera dorsalis (Diptera: Tephritidae) genetic sexing strain. Insects1110.3390/insects11110821 (2020). [DOI] [PMC free article] [PubMed]
- 46.Susanto, A. et al. Effect of various depths of pupation on adult emergence of interspecific hybrid of Bactrocera carambolae and Bactrocera dorsalis. Sci. Rep.12 (1), 4235. 10.1038/s41598-022-08295-w (2022). [DOI] [PMC free article] [PubMed] [Google Scholar]
- 47.Leksono, A. S., Gama, Z. P., Yanuwiadi, B., Rizali, A & Vera, Y. The effect of soil depth on pupation of Bactrocera dorsalis collected from chilli. In BIO Web of Conferences, 91, 01004. EDP Sciences. (2024). 10.1051/bioconf/20249101004
- 48.Hou, B., Xie, Q. & Zhang, R. Depth of pupation and survival of the Oriental fruit fly, bactrocera dorsalis (Diptera: Tephritidae) pupae at selected soil moistures. Appl. Entomol. Zool.41 (3), 515–520. 10.1303/aez.2006.515 (2006). [Google Scholar]
- 49.Samayoa, A. C. et al. Thermal effects on the development of bactrocera dorsalis (Hendel) (Diptera: Tephritidae) and model validation in Taiwan. Phytoparasitica46, 365–376. 10.1007/s12600-018-0674-6 (2018). [Google Scholar]
- 50.Choi, K. S., Samayoa, A. C., Hwang, S. Y., Huang, Y. B. & Ahn, J. J. Thermal effect on the fecundity and longevity of Bactrocera dorsalis adults and their improved oviposition model. PloS One. 15, 7, e0235910. 10.1371/journal.pone.0235910 (2020). [DOI] [PMC free article] [PubMed] [Google Scholar]
- 51.Lin, M. R. & Okuyama, T. Temperature-Dependent pupation depth in the Oriental fruit fly Bactrocera dorsalis and its implications for biological control. Insects15 (11), 873. 10.3390/insects15110873 (2024). [DOI] [PMC free article] [PubMed] [Google Scholar]
- 52.Dongmo-Kenfak, M. A. et al. Temperature-based phenology model to predict the development, survival, and reproduction of the Oriental fruit fly Bactrocera dorsalis. J. Therm. Biol.97, 102877. 10.1016/j.jtherbio.2021.102877 (2021). [DOI] [PubMed] [Google Scholar]
- 53.Chen, Q., Duan, Y., Wang, X., Zheng X. & Lu, W. Insights into pupal development of Bactrocera dorsalis: Factors influencing eclosion. Sci. Rep.14 (1), 27981. 10.1038/s41598-024-79526-5 (2024). [DOI] [PMC free article] [PubMed] [Google Scholar]
- 54.Plant Health Australia. The Australian Handbook for the Identification of Fruit Flies. Version 3.1. Plant Health Australia, Canberra, ACT. (2018).
- 55.Drew, R. A. I. & Romig, M. C. Keys to the Tropical Fruit Flies of South-East Asia: Tephritidae-Dacinae. CABI (2016).
- 56.Leksono, A. S. et al. The effect of water content in soil media on the hatchability of Bractocera dorsalis pupae. In BIO Web of Conferences, 154, 01005. EDP Sciences. (2025). 10.1051/bioconf/202515401005
- 57.Jaronski, S. T. Ecological factors in the inundative use of fungal entomopathogens. BioControl55, 159–185. 10.1007/s10526-009-9248-3 (2010). [Google Scholar]
- 58.Sukalkar, S. R., Kadam, T. A. & Bhosale, H. J. Optimization of chitinase production from Streptomyces macrosporeus M1. Res. J. Life Sci. Bioinform Pharm. Chem. Sci.4, 106–114. 10.26479/2018.0401.09 (2018). [Google Scholar]
- 59.Kaur, T., Vasudev, A., Sohal, S. K. & Manhas, R. K. Insecticidal and growth inhibitory potential of Streptomyces hydrogenans DH16 on major pest of india, Spodoptera Litura (Fab.) (Lepidoptera: Noctuidae). BMC Microbiol.14, 1–9. 10.1186/s12866-014-0227-1 (2014). [DOI] [PMC free article] [PubMed] [Google Scholar]
- 60.Arasu, M. V. et al. Antifeedant, larvicidal and growth inhibitory bioactivities of novel polyketide metabolite isolated from Streptomyces sp. AP-123 against Helicoverpa armigera and Spodoptera Litura. BMC Microbiol.13, 1–6. 10.1186/1471-2180-13-105 (2013). [DOI] [PMC free article] [PubMed] [Google Scholar]
- 61.Kokubu, T., Karube, I. & Suzuki, S. Protease production by immobilized mycelia of Streptomyces fradiae. Biotechnol. Bioeng.23 (1), 29–39. 10.1002/bit.260230104 (1981). [Google Scholar]
- 62.Zhang, Y. et al. A novel proteolysis-resistant lipase from keratinolytic Streptomyces fradiae var. k11. EMT42 (4), 346–352. 10.1016/j.enzmictec.2007.10.015 (2008). [Google Scholar]
- 63.Vurukonda, S. S. K. P., Giovanardi, D. & Stefani, E. Plant growth promoting and biocontrol activity of Streptomyces spp. As endophytes. Int. J. Mol. Sci.19 (4), 952. 10.3390/ijms19040952 (2018). [DOI] [PMC free article] [PubMed] [Google Scholar]
- 64.El-Sheikh, E. S. A. Comparative toxicity and sublethal effects of Emamectin benzoate, Lufenuron and spinosad on Spodoptera littoralis boisd. (Lepidoptera: Noctuidae). Crop Protec. 67, 228–234. 10.1016/j.cropro.2014.10.022 (2015). [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Data Availability Statement
The authors confirm that the data supporting the findings of this study are available within the article [and/or] its supplementary materials.