Toxicity assessment of four insecticides with different modes of action on pupae and adults of Eriopis connexa (Coleoptera: Coccinellidae), a relevant predator of the Neotropical Region

Abstract

Pesticides can be toxic to nontarget organisms including the natural enemies of agricultural pests, thus reducing the biodiversity of agroecosystems. The lethal and sublethal effects of four insecticides with different modes of action-pyriproxyfen, teflubenzuron, acetamiprid, and cypermethrin-were evaluated on pupae and adults of Eriopis connexa, an effective predator in horticultural crops. Pupal survival was reduced by pyriproxyfen (26 %) and cypermethrin (41 %). Malformations in adults emerged from treated pupae were observed after acetamiprid (82.7 and 100 % for 100 and 200 mg a.i./l, respectively), pyriproxyfen (48.6 %), and cypermethrin (13.3 %) treatments. A longer mean oviposition time was also observed in adults emerged from pupae treated with cypermethrin. Moreover, the latter insecticide as well as teflubenzuron did not reduce reproductive parameters, whereas females emerged from pyriproxyfen-treated pupae were not be able to lay eggs even when females showed large abdomens. Upon exposure of adults, survival was reduced to approximately 90 % by acetamiprid, but no reduction occurred with pyriproxyfen, teflubenzuron, or cypermethrin though the fecundity at fifth oviposition time of the female survivors was reduced. Pyriproxyfen decreased the hatching at all the oviposition times tested, whereas fertility was reduced in the fourth and fifth ovipositions by teflubenzuron and in the first and third ovipositions by cypermethrin. In conclusion, all four insecticides tested exhibited lethal or sublethal effects, or both, on E. connexa. The neurotoxic insecticides were more harmful than the insect-growth regulators, and pupae were more susceptible than adults. The toxicity of insecticides on the conservation of predators in agroecosystems of the Neotropical Region is discussed.

Activity of a selective insecticide (methoxyfenozide) against two mosquito species (Culex pipiensandCuliseta longiareolata): toxicological, biometrical and biochemical study

“…New selective insecticides such as IGDs have little or no impact on many beneficial organisms (Mordue et al, 2005;Merzendorfer, 2013;Fogel et al, 2016;Rodriguez-Saona et al, 2016). Thus, dibenzoylhydrazine compounds can be applied successfully as environmentally safe insecticides against lepidopteran and coleopteran insect species (Dhadialla et al, 1998;Pineda et al, 2004;Dhadialla et al, 2005;Dhadialla & Ross, 2007;Smagghe et al, 2012;Dallaire & Cusson, 2017).…”

Assessment of ecological risks of agrochemicals requires a new framework.

“…Examples include the lower fecundity of the pea aphid (Acyrthosiphon pisum) exposed to sublethal concentrations of Margosan-O extracts (active ingredient, azadirachtin) [66] and that of the cotton aphid (Aphis gossypii) exposed to cycloxaprid [67], both of which can help reduce the populations of those pests and achieve their effective long-term control. However, similar negative effects can be observed in beneficial, predatory and parasitoid arthropod species, such as the decrease in fecundity of predatory Coleomegilla maculata lady beetles after exposure to commercial formulations of 2,4-D and dicamba herbicides [68] and reduced ovipositions of Eriopis connexa lady beetles exposed to the insecticides teflubenzuron and cypermethrin [69]; the severe reduction in fecundity of predatory thrips (Scolothrips longicornis) exposed to abamectin [70]; or the reduced fecundity of the generalist predatory bug Orius armatus exposed to spinosad [71], amongst many others. Other non-target organisms also experience impaired reproductive effects; for example, the reduced fecundity of queen honey bees (Apis mellifera) exposed to sublethal doses of bifenthrin and deltamethrin [72] or to field relevant residues of imidacloprid [73,74]; the reduced spawning of Australian crimson-spotted rainbowfish (Melanotaenia fluviatilis) and medaka fish (Oryzias latipes) exposed to sublethal concentrations of esfenvalerate insecticide in water [75,76]; or the reduced population growth rate of Daphnia spp.…”

Selectivity of pesticides used in peach orchards to eggs and pupae of the predators Chrysoperla externa and Coleomegilla quadrifasciata

“…However, in the egg stage of C. quadrifasciata, deltamethrin (40) was classified as slightly harmful (class 2) ( Table 3). Fogel et al (2016) used cypermethrin at a dose of 25 mg a.i. L −1 in pupae of E. connexa pupae and observed a 41% reduction in pupal survival, which is similar to the result found in our study for deltamethrin (RLH of 43.94%) ( Table 3).…”