Comparative conventional preventive strategies for insect pest of okra

Abstract

The use of natural substances for pest control in agriculture is economically viable. It benefits both the human being and the environment due to its low persistence and toxicity. Therefore, the biopesticidal potential of three- plants-derived extracts (clove [Syzygium aromaticum], Hing [Hing (Asafetida)], and Wood Ash [Eucalyptus globulas]) was evaluated against different ' 'insect's pests on five okra varieties. All the treatments were sprayed at two stages, 1st before flowering and 2nd at the fruit-bearing stage. The results of the 24 h pre-spray revealed that the mean density of Aphis gossypii, Erias insulana, and Bemisia tabaci were significantly lower on a Shehzadi variety. However, among the treatments mean density of the A. gossypii and E. insulana after 1st and 2nd treatments were substantially more bass with E. globulas. Moreover, the Mean density of aphids was significantly lower after 72 h and 1-week time intervals. Furthermore, after 1st and 2nd treatments, the B. tabaci was considerably lower with hing on Shehzadi variety. It was found in the present study that the yield of five okra varieties was affected significantly by the application of the three treatments-pesticides. Among the various treatments, the application with E. globulas recorded a considerably higher crop yield. Therefore, clove, hing and E. globulas could be effective as alternative pest management methods. Furthermore, biopesticides generally are encouraged since they can proffer the solution of controlling insect pests without any environmental concern.

1. Introduction

Okra is most nutritious and concluded as an essential component of the human diet. Okra fruit is rich in vitamins (e.g., vitamin A, vitamin C, vitamin B6, folic acid, riboflavin, etc.), minerals (e.g., calcium, magnesium, potassium, iron, zinc, phosphorus, and β carotene), carbohydrates, proteins, fats and fiber (Varmudy, 2011). The fully ripened okra seed is an excellent source of oil, protein, unsaturated fatty acids (e.g., linoleic acid) necessary for human nutrition. Its ripened fruit and stem have crude fiber used in the paper industry (Kumar et al., 2013). Okra yield in Pakistan is much lower than that would lead okra producing country for many reasons, mainly because of insect pests (Rahman et al., 2012). Seventy-two types of insects have been observed on okra vegetables (Rahman et al., 2013) from vegetative to reproductive stage, which causes considerable damage. The major okra sucking pests are aphids (Aphis gossypii G.), thrips (Thrips tabaci L), and whiteflies (Bemisia tabaci G.). On the other hand, most pests are shooting borers (Earias spp.) and fruit borers (Helicoverpa armigera H.). Insect pest infestations reduce growth and lower growth and reduce the development and transmission of pathogens into okra (Sheedi, 1980, Dhaliwal et al., 1981).

Various methods used to control the different insect pest population. These methods include, chemical insecticides, biological control, synthetic insecticides, resistance varieties and semiochemicals which affect the growth of insect, development and population (Ahmed et al., 2013, Ahmed et al., 2016, Fu et al., 2017, Ahmed et al., 2018, Ahmed et al., 2019). However, some studies also indicated that the entomopathogenic fungi alone or/and plant extracts are effective to control the populations of insect pests (Saif-Ur-Rehman et al., 2019a, Saif-Ur-Rehman et al., 2019b, Mastoi et al., 2020, Sayed et al., 2021a, Sayed et al., 2021b). The best way of controlling insect pests at present is through synthetic insecticides that have traditionally been widely used (Ilyas et al., 2015, Ahmed et al., 2021, Iqbal et al., 2021, Ullah et al., 2021). Nonetheless, they have negative effect for humans, animals, and beneficial insects. (parasitic wasps, bees, and lady beetles). The field workers are highly vulnerable due to their frequent exposure to pesticides. Two million people have been reported affected by insecticide toxicity, and 40,000 have died (Pingali et al., 1994, Rajput, 2004, Solangi and Lohar, 2007). Furthermore, genetically engineered pesticides have been used in commercial agriculture and horticulture for a long time to prevent indiscriminate pesticides.. Biopesticides are effective in lower doses and allowed in organic farming. They are safer for providing an appropriate alternative for humans, animals, non-target organisms, plants, and bacteria. (Kumar et al., 2003, Patel et al., 2009, Ahmed et al., 2016, Ahmed et al., 2021, Iqbal et al., 2021).

Due to their potential insecticide effects, botanicals can be an approach to managing insect pests. The advantage of these bioinsecticides is that, unlike other poisons, these are readily available and cheaper. These are relatively easy available, less harmful to natural enemies, mammalian pollinators, and environmentally friendly. Misuse and -high insecticidal costs have forced the quest for alternatives, particularly for developing countries. Another approach is to research traditional methods of pesticide control. While they are mostly not widely employed in developed countries, they play essential roles in developing countries ' pesticide control programs. Plant parts and derivatives have been a traditional practice for many years (Owusu, 2001, Arannilewa et al., 2006, Adedire et al., 2011, Qari et al., 2020, Iqbal et al., 2021). Alternative solutions that are environmentally sustainable, affordable, and user-friendly (such as locally grown insecticide-powered plants) are required to combat this problem. Sand, dry pepper, and herbal extracts are just a few ancient ways discovered. Natural plant products such as volatile organic compounds and other products have been utilized to protect agricultural products against pests in several world regions for many years; Insecticide impacts on plant products against a wide range of pesticides have been discovered by a number of researchers (Tiroesele et al., 2015, Darshanee et al., 2017, Ahmed et al., 2018, Ahmed et al., 2019, Sharaby et al., 2020, Iqbal et al., 2021). The use of clove, Eucalyptus globulas, and hing are methods to be discussed. An approach based on plant products (without synthetic pesticides) in the present situation would seem to have tremendous potential for increasing okra production in the traditional crop system in all tropical and subtropical countries.

In previous studies with different purposes, okra and herbal extracts were used against various insect pests (Abdel et al., 2014, Iqbal et al., 2015, Sarkar et al., 2016). However, okra types and plant extracts were ineffective against aphids, whiteflies, or spotted bollworms (cloves, hing, and E. globulas). In this study, the potential utility for the control of insect pests on okra (aphid, bowls, and spotted bollworms) was evaluated with Hing, locally known as the Anja (Ana), clove (Syzygium aromaticum), locally known as Lowang ash, and clove, popularly known as the Lowang ash (E. globulas). This information would allow farmers in Pakistan to use readily available plant components to control insect pests and increase Okra yield.

2. Materials and methods

The experiment was conducted at the Agronomy Research Farm of the University of Agriculture, Peshawar, Pakistan. The experiment was laid out in Randomized Complete Block Design (RCBD) with a split-plot arrangement having 3 replications. Hing, clove, and E. globulas were used to test three conventional management techniques against okra insect pests on five varieties: Super green, Pusashawani, Tulsi, Shehzadi, and Green gold. Seeds were acquired from a local bazaar in Peshawar's Guru Mandi. The plot was confined to 5 × 4 m2, with a length of 5 m and a width of 4 m. Row to row distance was kept 25 cm, and plant to plant space was12 cm. A buffer zone of 1.5 m was marked between each replication and 1 m among the plots.

2.1. Preparation of extracts

Extracts of hing, clove, and E. globulas were prepared using the methodology of Munir (2006). Plant products were converted into powder form of approximately 3 mm in size with grinder help, locally controlled E. globulas (a traditionally made fireplace for cooking food). E. globulas (1 kg) was obtained from burnt fire wood use for cooking; sieved to remove particles/stone and were stored in plastic container properly until needed for bioassay. Two hundred fifty grams of each clove and hing were wrapped in Muslin fabric and steeped for 10 to 15 min in 5 L of water before boiling. After boiling, the solutions were kept for 24 h to get 5% (w/v) stock solution.

2.2. Data collection

Insect pest data were collected randomly in each sub-plot by selecting 5 plants (35 days old). Aphid data was collected by selecting each leaf from the plant's top, middle, and bottom based on the leaf base. Data were recorded per plant for whiteflies and borers. Twenty-four hours pre-spray and 24 h, 48 h, 72 h, and one-week post spray data were collected on 5 randomly selected plants in each subplot of each treatment. Spray application was repeated at two 'weeks' intervals.

2.3. Yield

Data of okra yield was obtained from each plot that was weighed through electrical balance and later converted into kg ha⁻¹ by using the following formula:.

$$\mathit{Yield}(kgh{a}^{-1})=Yieldofplotinkgx10,000m^2$$

$$\mathit{Areaofsubplot}(m^2)$$

2.4. Data Analysis

The collected data were subjected to Analysis of Variance, and means were compared using DMRT (1% probability level) using Originpro software version 2018. Figures were also obtained by Originpro software.

3. Results

Mean density of insect pests showed significant difference (F_4,1 = 4.16, P = 0.041) in between five okra varieties. Results reveal that the mean density of A. gossypii was significantly higher (4.73 A. gossypii leaf^-1) on Green gold followed by Super Green (4.43 A. gossypii leaf^-1) and Pussashawani (4.17 A. gossypii leaf^-1) while lower (2.73 A. gossypii leaf^-1) density was observed on Shehzadi which were significantly different from rest of the varieties. However, the mean density of bollworm was significantly higher (6.03 E. insulana plant⁻¹) on Pussa-shawani, followed by Green Gold (5.30 E. insulana plant⁻¹) and lower (3.53 E. insulana plant⁻¹) on Shehzadi. Furthermore, the mean density of B. tabaci was significantly higher (4.43B. tabaci plant⁻¹) on Green gold followed by Pussashawani (3.63B. tabaci plant⁻¹) and lower (2.73B. tabaci plant⁻¹) on Shehzadi similar to Tulsi (3.17B. tabaci plant⁻¹) and Super Green (3.43B. tabaci plant⁻¹). (Fig. 1).

Fig. 1.

Mean density of insect pests on five okra varieties before 24 h oftreatments.

Number of aphid’s leaf^-1 showed significant difference (F_4,1 = 154.15, P = 0.00) on different okra varieties when treated with plant extracts after first spray. Among the treatments mean density of the aphids was significantly lower (1.3 aphids leaf^-1) on Shahzadi (0.4 aphids) with E. globulas, which is followed by hing (0.9 aphids leaf^-1) and clove (1.9 aphids leaf^-1), while it was significantly higher in control (7.5 aphids leaf^-1) (Fig. 2a). However, the mean density of aphids was significantly lower after 72 h of treatment and higher after 24 h. In varieties, x time interval interaction plots in which shehzadi variety was practiced and sprayed interval of 48 h, 72 h and one week yielded a significantly lower mean density of aphids (1.6 aphids leaf^-1) on Shahzadi and higher on Super Green (4.5 aphids leaf^-1) (Fig. 2b). Furthermore, Moreover, Treatment and varieties interaction showed significant difference (F_4,1 = 8.71, P = 0.000) after second spray. Among the treatments mean density of the aphids was significantly lower (0.0 aphids leaf^-1) with E. globulas on Shehzadi, which was followed by hing (0.6 aphids leaf^-1) (Fig. 2c). However, higher A. gossypii (7.7 aphids leaf^-1) was observed in the control. Furthermore, the Mean density of aphids was significantly lower after 1 week of treatment (0.6aphids leaf^-1) and higher (5.9 aphids leaf^-1) after 24 h on Green Gold (Fig. 2d). Moreover, Mean density of Bemisia tabaci after first spray-on five varieties of okra showed significantly difference (F_4,1 = 9.10, P = 0.001) at 5% level. The treatments mean density of the B. tabaci was significantly lower (0.6B. tabaci plant⁻¹) with hing on Shehzadi while it was significantly higher in control (7.7B. tabaci plant⁻¹) on Pussa-Shawani (Fig. 3a). Meanwhile, there was no significant difference among the spraying intervals (24 h, 48 h, 72 h and 1 week) (Fig. 3b). Among the treatments mean density of the B. tabaci was significantly lower (0.1B. tabaci plant⁻¹) with hing on Shehzadi, which was followed by Tulsi and Green Gold (0.6B. tabaci plant⁻¹) while it was significantly higher in control (6.1B. tabaci plant⁻¹) on Super Green (Fig. 3C). In varieties, x time interval interaction plots in which Shehzadi variety was practiced and spray 1 week yielded significantly lower mean density of aphids (1.4B. tabaci plant⁻¹) (Fig. 3d). Mean density of E. insulana after first spray-on five varieties of okra showed significantly difference (F_4,1 = 8.10, P = 0.004) at 5% level. Among the treatments density of the E. insulana was significantly lower (0.6 E. insulana plant⁻¹) on Shehzadi with E. globulas, while it was significantly higher in control (7.7 E. insulana plant⁻¹) on Pussa-Shawani (Fig. 4a). However, in varieties, x time interval interaction plots in which Shehzadi variety was practiced and all the spray intervals yielded a significantly lower density of E. insulana (1.9 E. insulana plant⁻¹) (Fig. 4b). Nevertheless, The results reveal that the mean density of E. insulana after 2nd spray was significant difference. Among the varieties mean density of E. insulana was significantly lower on Shehzadi (0.8 E. insulana plant⁻¹) with hing and higher (7.1 E. insulana plant⁻¹) with Control on PussaShawani (Fig. 4C). In varieties, x time interval interaction plots in which Shehzadi variety was grown and 1 week after treatment resulted in a significantly lower mean density of E. insulana (0.7 E. insulana plant⁻¹) (Fig. 4d).

Fig. 2.

Mean Density of Aphis gossypii after first (a) and second spray (b)on five varieties of okra, (c)the interaction between varieties and plant extracts and (d) the interaction between time intervals and okra varieties.

Fig. 3.

Mean density of Bemisia tabaci after first (a) and second spray (b)on five varieties of okra, (c) the interaction between varieties and plant extracts and (d) the interaction between time intervals and okra varieties.

Fig. 4.

Mean larval density of Erias insulana after first (a) and second spray (b)on five varieties of okra, (c) theinteraction between varieties and plant extracts and (d) the interaction between time intervals and okra varieties.

Furthermore, it was found in the present study that the yield of five okra varieties was significantly affected by the application of the three treatments. Among the varieties, Shehzadi yielded significantly (F_4,1 = 5.95, P = 0.000) higher with 11826 kg ha⁻¹ significantly different from other varieties. However, Among the various treatments, E. globulas application gave a significantly (F_4,1 = 48.52, P = 0.000) higher yield of 12021 kg ha^−1, significantly different from others. Among the interactions (treatment × varieties), E. globulas, when sprinkled on the Shehzadi variety, gave a higher yield (12582kgha⁻¹) of okra (Fig. 5).

Fig. 5.

Mean yield (kg ha⁻¹) of five okra varieties after treatments.

4. Discussion

Natural pesticides are an excellent alternative to synthetic pesticides because they are safe for the environment, natural enemies, humans, and other animals (Sayed et al., 2020, Ahmed et al., 2021, Iqbal et al., 2021). The okra is one of the vegetables frequently picked from the field and probably picked daily; hence highly toxic chemicals might leave residual effects in consumable pods. This research indicated that clove, hing, and E. globulas could reduce the infestation of ' 'insect pests and improve the yield of the okra plant. Furthermore, the research suggested that E. globulas and hing based biopesticides were adequately effective in controlling Aphis gossypii and E. insulana whereas, hing was more effective, especially against B. tabaci infesting okra.

Aphids and Spotted Bollworms population decreased after 72 hrs. But their toxicity was close to peaks of reduction percent up to one week during the second spray. After 72 h of spraying, the botanical pesticides began to detox, and the maximum effect on the population of Aphides and Spotted Bollworms was lowered until one week after the rush. It is generally observed that synthetic pesticides reduce insect infestation immediately, but develops resistance against these pesticides. However, biopesticides are natural substances, and insects never tolerate the efficacy of biopesticides. Our results are similar to that of Rani and Jyothsna (2010). They had observed that plants produce some morphological advances and protein that have toxic, repellent or anti-nutritional effects on the herbivores. In the present study, the mean density of A. gossypii and E. insulana was significantly lower on the Shehzadi variety, which might be attributed to morphological features or the production of secondary metabolites. Such components are responsible for reducing insect pest preferences for a variety. The present study presents study's results supported by Siva-Kumar (2004), who reported that Meranoplus bicolor was found useful to control insect feeding on the flowers and at the base of immature bolls of cotton. Ali et al. (2005), also reported that bio-pesticides controlled sucking complex populations on cotton. The least values of the insect population, under the E. globulas extract compared to hing and clove extract, proved that it was most effective against aphids and spotted bollworms in the okra variety of Shehzadi. Because of this, it had the highest yield of the okra variety Shehzadi, which explained its high monetary value.

In agriculture systems where environmental protection and the conservation of beneficial organisms is essential, the application of bio-pesticides that provide desirable alternatives to synthetic chemicals is increased in recent years, with synthetic chemicals in agriculture systems to protect the environment and preserve beneficial microorganisms (Ahmed et al., 2021, Iqbal et al., 2021). However, there have been little or no attempts to control insect pests of Okra plants using these plant extracts, mostly E. globulas. Repellence or suppression by E. globulas of 'insect pests on Okra Shehzadi species could be an antimicrobial effect of alkanes in E. globulas. Nevertheless, Super Green, Pussasha Wani, and Green Gold were highly susceptible to aphids, whitefly and spotted bollworms. This highest number of these insect populations may be due to hosts and favorable environmental conditions. Another important reason for the abundance may be the season of the pest. Our results are supported by Sohail et al. (2015).

Likewise, the E. globulas application gave lower E. insulana density, which might be due to bollworms' feeding behavior. As a result, our findings matched those of Lal and Verma. (2006), who found that E. globulas could successfully reduce sucking and chewing insects. They observed that lupron and E. globulas dusting was best in managing the pest population long-term. Similarly, Aderolu et al. (2012) reported that neem and E. globulas had affected insect pests and the number of damaged leaves per plant of amaranths plant. E. insulana was significantly lower on Shezadi and with E. globulas treatment. Shehzadi variety was non-preferred by the E. insulana due to some plant characters like trichome. Similar results were also reported by Mohamed (2012). The chewing type behavior of bollworms might be the main reason for its control. Further, in our study, the pest attack was reduced in the Shehzadi variety due to physical characteristics like setae, trichome, etc. Similar results were also reported by Hanley et al. (2007). They had studied plant defenses against insect pests due to physical properties, either forming waxy cuticles or developing spines or setae. Our study based on reducing the mean population of whitefly with hing is partially favored by Kaleri et al. (2011) and Khan et al. (2014). They reported the efficacy of different plant extracts regarding percentage reduction of the whitefly population after hing application. Our results also aligned with that of Noonari et al. (2016). They had stated that maximum removal of the whitefly population occurs with hing application (60.18%).

Among the varieties mean density of B. tabaci after the 1st and 2nd treatments was significantly lower on Shehzadi and higher on Green gold. There was no significant difference among the spraying intervals (24 h, 48 h, 72 h, and 1 week) after the 1st treatment. Still, the time interval of 1 week after the 2nd treatment yielded significantly lower (2.2B. tabaci plant⁻¹), while 24 h after treatment gave substantially higher (4.0B. tabaci plant⁻¹). Similarly, Mahmood et al. (2014) found a significant reduction in the whiteflies population after 24 hrs, 48 hrs,72 hrs when treated with hing application. Ali et al. (2011) also reported similar results. The present study revealed that B. tabaci density was significantly reduced with the application of hing. The current investigation's present findings showed that the botanical pesticides effectively reducing the whitefly population up to one week with maximum reduction after one week of spray.

With an increasing awareness of environmental pollution, the natural-products concept has returned to the global arena as a proposed alternative for pest control. Natural products reportedly have reduced environmental consequences, leading to several studies' emergence (Ahmed et al., 2021, Iqbal et al., 2021). Before synthetic insecticides' development and commercial success beginning in the 1940 s, botanical insecticides were effective weapons in the ' 'farmer's arsenal against crop pests (Isman, 2008). Plant extracts have been found to take comparatively more days to combat sucking insects. However, previous studies have documented that while synthetic insecticides are quicker than botanicals in their regulation, they negatively affect biocontrol agents (Khan and Atta, 2007, Oladimeji and Kannike, 2010, Khaliq et al., 2014, Ursani et al., 2014). The extracts of the plant contain many substances which have been toxic to sucking and chewing insects. Hing will disrupt the chemoreceptors, which prevent insects from feeding. It also acts like a repellent, larvicidal egg, stimulates the hatching of eggs, and reduces insect pests' reproduction. (Iqbal et al., 2015). The Hing contains the biodegradable, insecticidal liminoid, a botanical insect inhibitor (Walter et al., 1999), which interacts with some cellular proteins that contribute to developmental harms such as insect growth and premature death (Upadhyay and Singh, 2012).

Clove oil is being tested against several urban and agricultural pests, and some insecticides have been proven to be effective against some of them. Many other plant products have been tested and found to be effective against imported red Prevent workers, including mint oil and cinnamon oil (Kim et al., 2003, Yang et al., 2003; Chaieb et al., 2007, Chang et al., 2013). Clove was successful against sucking insects in the current study. It may be because the insecticidal activity of different extracts of plants and different concentrations remained unchanged. In this respect, too, the time factor is essential. Plant extracts usually contain many metabolites that operate through different modes of action with sub-lethal effects on the target insect (Chiasson et al., 2004). The results are similar to Mahdi and Rahman (2008), who tested spices against stored beetles for toxicity. Zeng et al. (2010) assessed and evaluated the clove's chemical components utilizing GC–MS. There were 18 active compounds and 9 identified. The main element of 2-methoxy-4-(2-propenyl)-phenol was identified as 83 percent. Trans-Caryophyllene activity (12%) was also associated with insecticidal properties. Insects can also be used to control contact and fumigant actions of plant extracts due to their ability to influence various insect life stages (Han et al., 2008, Tripathi et al., 2009). Further research should also focus on active ingredients and identify the optimal application methods for natural plant extracts.

The highest yield was recorded in Shehzadi (12582 Kg/ha) treated with wood compared to other varieties treated with hing and clove. This increase in outcome might be associated with its resistance to different insect pests. Our results agree with that of some previous research, i.e., Shannag et al. (2007) had reported that the yield of okra was low with a high infestation of insect pests. Similarly, plots treated with E. globulas yielded significantly higher yields than control and other treatments (hing, clove). Our results conforming to Mahmood et al. (2010). Accordingly, the highest yield of cucumbers was achieved from plots treated with E. globulas + permethrin dust. Ukeh et al. (2007) also recorded the highest output from okra plots treated with E. globulas. The yields obtained from treated plots of plant extracts were considerably higher, in line with Fuglie, 1998, Panhwar, 2002, who reported that the extract of the treated plants on the cowpea field increased flower production per plant. The main threat to crop production was the infestation of insect pests on the farm. These results align with previous researchers ' observations, which found that plant extract increases vegetable and pea crops' yield by protecting them from insect pests (Panhwar, 2002). Gaby (2000), likewise, showed a significant increase in plant yield when using plant extract in powder or solution. Field findings indicated no phototoxic effect on the okra leaves was generated by any of the extracts used in this study. The study findings conflicted with, who claimed that neem products induced yellowing and subsequent leaves to be discarded. If it is sprayed early morning or late evening, plant-based insecticide application effectiveness can be enhanced (Oparaeke et al., 2003).

5. Conclusion

These results showed a significant difference in efficiency of treatments with the plant extracts as compared to the control. The yield in plots dealing with plant extracts was relatively higher than that of in control plots. Reduced production in the Okra plant in the control group is related to high pest infestation. The more a farmer avoids using the insecticidal solution, the more the farm becomes exposed to high pests; this could result from non - application of either the hing and clove extract or the E. globulas extract. If botanicals are applied initially, the population could be kept below the economic injury level, an essential point of IPM. Therefore, this study promotes and developing local plants as protectants against insect pest infestations. It is also suggested to investigate the effect of these natural products in the farm environment on controlling the sucking insect pests under laboratory conditions.

6. Availability of data and material

All data related to this paper are available in the manuscript.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.