Table 3.
Published examples reporting a greater than additive result for insecticidal protein combinations
| Number of examples | Level of synergy reported (x-fold) |
Insecticidal proteins |
Insect | Additivity model | Assessment method used | Model assumption concerns (type) | Other comments | References |
|---|---|---|---|---|---|---|---|---|
| 9 | 1.24 to 5.24 | Cry1Aa, Cry1Ab, Cry1Ac | Maize stem borer (Chilo partellus) | CA | Tabashnik eq. 5 | CA model not justified by dose–response slopes (used slopes which varied by 4–10-fold or more) | ― | Sharma et al. (2010) |
| 1 | 14.3 | Vip3Aa, Cry1Ca | Sugarcane borer (Diatraea saccharalis) | CA | Tabashnik eq. 5 | CA model not justified by dose-response slopes (used slopes which varied by 2.9-fold) | upper end of dose–response not well-represented; precision very poor for LC90 values | Lemes et al. (2014) |
| 1 | 1.03 | Cry1Ac, Cry1Fa | Cotton bollworm (Helicoverpa armigera) | CA | Tabashnik eq. 5 | CA model not justified by dose–response slopes (dose–response could not be determined for 1 of the 2 proteins) | ― | Ibargutxi et al. (2008) |
| 2 | 1.06 to 1.10 | Cry1Ac, Cry1Fa | Earias insulana | CA | Tabashnik eq. 5 | ―a | ― | Ibargutxi et al. (2008) |
| 3 | 1.58 to 3.12 | Cry1Ac, Cry2Ab | Cotton bollworm (Helicoverpa armigera) | CA | Tabashnik eq. 5 | ― | ― | Ibargutxi et al. (2008) |
| 3 | 1.38 to 1.75 | Cry1Ac, Cry1Fa | Cotton bollworm (Helicoverpa armigera) | CA | Tabashnik eq. 5 | ― | Measured growth inhibition | Ibargutxi et al. (2008) |
| 1 | 1.11 | Cry1Ac, Cry1Fa | Earias insulana | CA | Tabashnik eq. 5 | ― | Measured growth inhibition | Ibargutxi et al. (2008) |
| 2 | 1.07 to 1.40 | Cry1Ac, Cry2Ab | Cotton bollworm (Helicoverpa armigera) | CA | Tabashnik eq. 5 | ― | Measured growth inhibition; high heterogeneity across protein responses | Ibargutxi et al. (2008) |
| 2 | 1.13 to 1.23 | Cry1Ac, Cry2Ab | Earias insulana | CA | Tabashnik eq. 5 | ― | Measured growth inhibition; high heterogeneity across protein responses | Ibargutxi et al. (2008) |
| 5 | 1.6 to 4.92 | Cry1Aa, Cry1Ab, Cry1Ac, Cry1Ca | Maize stem borer (Chilo partellus) | CA | Tabashnik eq. 5 | ― | multiple insects (10) per test arena; purity of proteins not shown; some details of diet incorporation not shown/referenced | Gao et al. (2010) |
| 1 | 1.6 | Cry1Aa, Cry1Ab | Pink stem borer (Sesamia inferens) | CA | Tabashnik eq. 5 | ― | ― | Gao et al. (2010) |
| 1 | 11.0 | Cry1Ab, Cry1Ba | Maize stem borer (Chilo partellus) | CA | Tabashnik eq. 5 | CA model not justified by dose–response slopes (used slopes which varied by 2.4-fold) | ― | Gao et al. (2010) |
| 1 | 4.46 | Cry1Ac, Cry1Ba | Maize stem borer (Chilo partellus) | CA | Tabashnik eq. 5 | CA model not justified by dose–response slopes (used slopes which varied by 1.8-fold) | ― | Gao et al. (2010) |
| 1 | 1.60 | Cry1Ac- Cry1Ca | Cotton bollworm (Helicoverpa armigera) | CA | Tabashnik eq. 5 | ― | used droplet-feeding method | Li and Bouwer (2014) |
| 1 | 4.13 | Cry1Ab- Cry1Ca | Cotton bollworm (Helicoverpa armigera) | CA | Tabashnik eq. 5 | ― | ― | Li and Bouwer (2014) |
| 1 | 1.72 | Cry1Aa- Cry1Ca | Cotton bollworm (Helicoverpa armigera) | CA | Tabashnik eq. 5 | ― | ― | Li and Bouwer (2014) |
| 2 | 1.02 to 1.14 | Cry1Ac- Cry2Aa or Cry9Aa | Cotton bollworm (Helicoverpa armigera) | CA | Tabashnik eq. 5 | ― | ― | Li and Bouwer (2014) |
| 1 | 1.37 | Cry2Aa- Cry9Aa | Cotton bollworm (Helicoverpa armigera) | CA | Tabashnik eq. 5 | ― | ― | Li and Bouwer (2014) |
| 1 | 1.18 | Cry1Ca- Cry2Aa | Cotton bollworm (Helicoverpa armigera) | CA | Tabashnik eq. 5 | ― | ― | Li and Bouwer (2014) |
| 1 | 2.29 | Cry1Ca- Cry9Aa | Cotton bollworm (Helicoverpa armigera) | CA | Tabashnik eq. 5 | ― | ― | Li and Bouwer (2014) |
| 3 | 1.01 to 1.43 | Cry1Ba, Cry1Ca, Cry1Da | Bean shoot borer (Epinotia aporema) | CA | Tabashnik eq. 5 | CA model not justified by dose–response slopes (dose–response could not be determined for 1 of the 3 proteins which was used in 2 comparisons) | ― | Sauka et al. (2007) |
| 2 | ≤ 25% increased mortality | Cry1AbMod, Cry1Ac, Cry2Ab | Pink bollworm (Pectinophora gossypiella) | RA | Colby method | ― | only 2 out of 11 combinations statistically significant.; 7 out of 11 qualitatively greater, but only 3 at plus 13% or greater | Tabashnik et al. (2013) |
| 2 | ≤ 10% increased mortality | Cry1Ac, Cry2Ab | Cotton bollworm (Helicoverpa armigera) | RA | Colby method with t-test | ― | only 2 out of 36 combinations statistically significant.; 7 out of 36 qualitatively greater | Wei et al. (2015) |
| 1 | 21% increased mortality | Cry1Ab, Cry1C | Diamondback moth (Plutella xylostella) | RA | Colby method | ― | Only 1 combination used; purity of substances not shown; used leaf-dip method | Mittal et al. 2007 |
| 1 | 1.5 | Cry1Ab, Cry1Ac | Gypsy moth (L. dispar) | CA | Tabashnik eq. 5 | ― | Force-feeding bioassay; measured weight in 4th instar larvae | Lee et al. (1996) |
| 5 | 2.7 to 4.9 | Cry1Aa, Cry1Ac | Gypsy moth (L. dispar) | CA | Tabashnik eq. 5 | ― | Force-feeding bioassay; measured weight in 4th instar larvae | Lee et al. (1996) |
| 1 | 7.3 | Cry1Aa, Cry1Ac | Gypsy moth (L. dispar) | CA | Tabashnik eq. 5 | ― | Force-feeding bioassay; measured weight in 4th instar larvae; wide estimate for the ID50 (9.2-fold), but even at its max, it would still suggest a 4.6-fold effect | Lee et al. (1996) |
| 1 | 1.46 | Cry9Ca, Vip3Aa7 | Diamondback moth (Plutella xylostella) | CA | Tabashnik eq. 5 | CA model not justified by dose–response slopes (used slopes which varied by 2.1-fold) | multiple insects (10) per test arena; used leaf-dip/ application method | Dong et al. (2012) |
| 5 | 2.2 to 5.3 | Cry1Ac:Cry1Ie | Asian corn borer (Ostrinia furnacalis) |
CA | Tabashnik eq. 5 | Slopes of dose–responses not described | purity information not given; inconsistent trend as ratios change | Jiang et al. (2016) |
a― = none noted.