Toxicological risk assessment of some commonly used insecticides on cotesia flavipes, a larval parasitoid of the spotted stem borer chilo partellus

Authors: RAEN-AKHTAR, ZUNNU - University Of Faisalabad; TARIQ, KALEEM - Abdul Wali Khan University; Handler, Alfred - Al; ALI, ASAD - Abdul Wali Khan University; ZANG,, LIAN-SHENG - Jilan University; ULLAH, FARMAN - China Agricultural University; ALI, SAJJAD - University Of Sargodha; ULLAH, MUHAMMAD - University Of Sargodha

Submitted to: Ecotoxicology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/14/2021
Publication Date: 3/15/2021
Citation: Raen-Akhtar, Z., Tariq, K., Handler, A.M., Ali, A., Zang,, L., Ullah, F., Ali, S., Ullah, M.I. 2021. Toxicological risk assessment of some commonly used insecticides on cotesia flavipes, a larval parasitoid of the spotted stem borer chilo partellus. Ecotoxicology. 30(3):448-458. https://doi.org/10.1007/s10646-021-02372-y.
DOI: https://doi.org/10.1007/s10646-021-02372-y

Interpretive Summary: Parasitoid wasps that are natural enemies of pest insect species, such as the spotted stem borer moth, are important components of integrated pest management (IPM) strategies to limit pest populations. As part of IPM programs, it is essential to employ insecticides that are effective in controlling the pest species but have limited or no harmful activities in natural and released augmentative parasitoids. Scientists from Universities in Pakistan, the University of Florida and USDA, Agriculture Research Service, Center for Medical, Agricultural and Veterinary Entomology, Gainesville, Florida, collaborated to assess the relative toxicity of commonly used insecticides, to control the spotted stem borer moth, on its natural parasitoid. Risk quotient analysis toxicity tests were developed that showed that organophosphates were highly toxic to the parasitoid while neonicotinoids such as imidacloprid and acetamiprid were least toxic. This study provides critical information relevant to the efficacious use of insecticides for the IPM control of the spotted stem borer. The study also establishes an analytical tool to evaluate insecticide use in other IPM programs that concomitantly release natural predator and/or parasitoids to control pest insects in order to measure the impact of the insecticide on both the target pest and the beneficial parasitoids and predators used for control.

Technical Abstract: BACKGROUND: Cotesia flavipes Cameron is an important larval parasitoid exploited for the control of the spotted stem borer, Chilo partellus. However, non-target effects of commonly used insecticides on this parasitoid, when used to control C. partellus, have yet to be evaluated. Here we evaluate the lethal and sublethal effects of twelve commonly used insecticides on C. flavipes. RESULTS: Residual toxicity tests showed that organophosphates (chlorpyrifos, triazophos and profenofos) exhibited highest contact toxicity to C. flavipes adults with an LC50 range of 0.63 to 1.05 mg a.i/l, while neonicotinoids (nitenpyram, acetamiprid and imidacloprid) were less toxic to C. flavipes with an LC50 range of 1.27 to 139.48 mg a.i/l. Sugar-insecticide feeding bioassays showed that organophosphates, pyrethroids (cypermethrin, bifenthrin and lambda-cyhalothrin) and carbamates (thiodicarb, carbaryl and methomyl) were highly toxic to C. flavipes adults and caused 100% mortality at 48 hours of exposure, while neonicotinoids caused 66% mortality at 48 hours of exposure. Risk quotient analysis showed that among all tested insecticides, imidacloprid and acetamiprid were less toxic to C. flavipes adults with a risk quotient value of 0.88 and 1.6 respectively. Furthermore, exposure of immature C. flavipes through their host bodies significantly decreased the parasitism rate at their F1 and F2 generations. CONCLUSION: Risk quotient analysis of insecticides indicated that imidacloprid and acetamiprid were the least toxic to C. flavipes. This study provides important information to pest control managers in their effort to incorporate appropriate insecticides in integrated pest management programs.