Toxicity of some insecticides used in maize crop on Trichogramma pretiosum (Hymenoptera, Trichogrammatidae) immature stages

Abstract

Fall armyworm Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae) is an important pest of maize (Zea mays L.) crops in Brazil. The effects of beta-cypermethrin, chlorfenapyr, chlorpyrifos, spinosad, etofenprox, triflumuron, alpha-cypermethrin/teflubenzuron, and lambda-cyhalothrin/thiamethoxam on Trichogramma pretiosum Riley, 1879 (Hymenoptera: Trichogrammatidae) immature stages were evaluated. Eggs of Anagasta kuehniella (Zeller, 1879) (Lepidoptera: Pyralidae), containing immature stages of the parasitoid were dipped in water solution pesticides, to evaluate their effects on emergence and sex ratio of F1 parasitoids. For F2 parasitoids, emergence, parasitism capacity, and sex ratio were evaluated. Beta-cypermethrin, chlorfenapyr, chlorpyrifos, and spinosad affected the emergence success of F1 T. pretiosum. Insects exposed to etofenprox and alpha-cypermethrin/teflubenzuron during the egg-larval period and to lambda-cyhalothrin/thiamethoxam during the pupal stage also suffered reduction in the emergence. Beta-cypermethrin affected the sex ratio of F1 T. pretiosum from host eggs treated during the egg-larval period; spinosad affected it during the egg-larval period and the pupal stage, whereas chlorpyrifos did the same when applied during the pupal stage. Chlorpyrifos also affected the sex ratio of F2 parasitoids, but only when applied during the egg-larval period, whereas chlorfenapyr reduced this trait when applied during the pre-pupal phase. Chlorpyrifos and alpha-cypermethrin/teflubenzuron affected the parasitism capacity of F1 females from eggs treated during the egg-larval period. Considering the overall effects, only etofenprox and triflumuron were selective on T. pretiosum when applied on parasitized A. kuehniella eggs. Further studies need to be carried out to verify the toxicity of the other pesticides under semi-field and field conditions.

Lethal and Sublethal Effects of Various Pesticides on Trichogramma achaeae (Hymenoptera: Trichogrammatidae)

“…The negative effects of pesticides on natural enemies induce the necessity to study their side effects to adjust chemical and biological control programs and reduce the negative impacts of pesticides on non-target organisms (Souza et al 2014, Ghorbani et al 2016. Pesticides have lethal and sublethal effects on arthropods, as they can kill these organisms or negatively affect various biological parameters (Desneux et al 2007, Garcia et al 2009, Cordeiro et al 2010, Castro et al 2012.…”

Selectivity of Insecticides Against Telenomus podisi Ashmead (Hymenoptera: Platygastridae) on Corn

“…F. Bueno, R. C. O. F. Bueno, Parra, & Vieira, 2008), T. remus (Carmo et al, 2010), and T. podisi (Turchen et al, 2015). However, this same product, used in the same dosage of this study, can vary from harmless to harmful, depending on the developmental stage of the natural enemy (Souza, Carvalho, Moura, Couto & Maia, 2014). Parasitoid pupae and larvae might be more resistant to pesticides, compared to adults, because they develop inside the host egg, which is protected against insecticides by the chorion (Stecca, Bueno, Pasini, Silva, Andrade, & Filho, 2016).…”

Pesticide selectivity to natural enemies: challenges and constraints for research and field recommendation

“…The same product used at the same rate can range from harmless to harmful, depending on the developmental stage of the natural enemy (SOUZA et al, 2014). For example, the insecticide bifenthrin 5g a.i.…”