Acute and population level toxicity of imidacloprid and fenpyroximate on an important egg parasitoid, Trichogramma cacoeciae (Hymenoptera: Trichogrammatidae)

Abstract

One focus of integrated pest management (IPM) is the use of biological and chemical control in an optimal way. The availability of selective pesticides is important as is information about both lethal and sublethal effects of pesticides on biocontrol agents. Acute and sublethal effects of imidacloprid and fenpyroximate exposure were studied on adult stage of egg parasitoid Trichogramma cacoeciae Marchal and the emergence rate and life table parameters were determined. The adult wasps were exposed to field recommended concentration (FRC) of the pesticides on glass plates. Field rates of imidacloprid and fenpyroximate caused 100 and 32% adult mortality, respectively. Based on concentration-response experiments, the LC(50) values of imidacloprid and fenpyroximate were 6.25 and 1,949 ppm, respectively. The effect of imidacloprid and fenpyroximate on larvae, prepupae and pupae of the parasitoid was tested by exposing parasitized eggs of Sitotroga cerealella Olivier or Cydia pomonella L. to the FRC. Imidacloprid and fenpyroximate reduced adult emergence by 10.7 and 29%, respectively, when S. cerealella eggs were used as the host and 10.9 and 24.9%, respectively, when C. pomonella eggs were used as the host. Population parameters of emerged adults from treated pre-imaginal stages by FRC of the pesticides were also studied. The parameters were longevity and progeny production of emergent adults and also intrinsic rate of increase (r ( m )), generation time (T) and doubling time (DT). Longevity and progeny production of the emergent adults was not affected by pesticide exposure in comparison to the control. In addition, none of population parameters such as r ( m ), T and DT were affected by pesticide exposure. The intrinsic rate of increase for the control, fenpyroximate and imidacloprid exposed populations were 0.388, 0.374, and 0.372 female offspring per female per day, respectively. Overall, results of this study suggest a relative compatibility between fenpyroximate and T. cacoeciae, but imidacloprid showed deleterious effects on adults of the parasitoid.

Lethal effect of imidacloprid on the coccinellid predator Serangium japonicum and sublethal effects on predator voracity and on functional response to the whitefly Bemisia tabaci

“…Occurrence of such effects is likely given the multiple ways natural enemies could be exposed to pesticides. Sublethal effects can impair various key processes of natural enemies' efficacy against pests (Desneux et al 2006c(Desneux et al , 2007Thornham et al 2008;Suma et al 2009;Evans Samuel et al 2010;Arnó and Gabarra 2011;Saber 2011;Stara et al 2011;Castro et al 2012). Given the multiple possible behavioral effects, functional response of predators to prey could be impaired by pesticides (Wang and Shen 2002;Poletti et al 2007).…”

Performance of four Trichogramma species (Hymenoptera: Trichogrammatidae) as biocontrol agents of Heliothis virescens (Lepidoptera: Noctuidae) under various temperature regimes

“…Chemical control is the main tactic to control H. virescens damage to cotton (Cook et al 2005;Moscardini et al 2008) but widespread use of chemical and biological insecticides (such as Bacillus thuringiensis products) ultimately leads to the selection of resistant pest strains (Gassmann et al 2009;Daane and Johnson 2010). In addition, insecticides are harmful to the environment and human health, and they have multiple potential side effects on beneficial arthropods (Desneux et al 2007;Hong et al 2009;Vianna et al 2009;Saber 2011). The development of more environmentally sound and sustainable management methods can help prevent the selection of resistant pests, environmental damage and ultimately prevent losses in the production chain (Heckel et al 1998;McCaffery 1998).…”

Susceptibility to Selected Insecticides and Risk Assessment in the Insect Egg Parasitoid <I>Trichogramma confusum</I> (Hymenoptera: Trichogrammatidae)

“…Imidacloprid is relatively nontoxic to T. confusum (Zhang 1997). However, some exceptions do occur, for example, imidacloprid has been reported to be harmful to T. chilonis, T. cacoeciae Marchal, and T. brassicae Westwood (Preetha et al 2010a, Saber 2011.…”

“…Thus, laboratory studies are useful for predicting the response of natural enemies to insecticide applications (Naranjo 2001). There are several records showing that insecticides have effects on Trichogramma wasps, but few records on T. confusum (Zhang 1997;Cô nsoli et al 1998Cô nsoli et al , 2001Hassan et al 1998;Suh et al 2000;Youssef et al 2004;Bastos et al 2006;Saber 2011). Knowing the toxic effects of commonly used insecticides on T. confusum is important when considering the potential of this species in IPM.…”