Acute toxicity of lethal and sublethal concentrations of neonicotinoid, insect growth regulator and diamide insecticides on natural enemies of the woolly apple aphid and the obscure mealybug

Abstract

Based on the importance of using low-risk compounds to protect beneficial agents, the present study evaluated the acute toxicity of lethal and sublethal concentrations of the insecticides thiacloprid, pyriproxyfen, and chlorantraniliprole on adults of Aphelinus mali (Haldeman), the main parasitoid of the woolly apple aphid, Eriosoma lanigerum (Hausmann). Similarly, acetamiprid, buprofezin, pyriproxyfen, chlorantraniliprole and cyantraniliprole were evaluated on adults of the parasitoid Acerophagus flavidulus (Brethés) and also on larvae and adults of the predator Cryptolaemus montrouzieri Mulsant, both species important natural enemies of the obscure mealybug, Pseudococcus viburni (Signoret). Natural enemies were exposed to insecticide residues of minimum recommended rate (1x) and between one to four concentrations (0.5x, 0.25x, 0.1x and 0.05x) of the minimum recommended rate on apple leaves. Our results indicate that thiacloprid was moderately harmful to A. mali at 1x, and acetamiprid was harmful to A. flavidulus causing 100% mortality from 0.1x to 1x concentrations. Buprofezin, pyriproxyfen and chlorantraniliprole were harmless or slightly harmful for both parasitoids. Cyantraniliprole was slightly harmful from 0.25x to 1x for A. flavidulus. For C. montrouzieri, acetamiprid was harmless or slightly harmful for larvae and adults on the concentrations evaluated. Buprofezin, pyriproxyfen and chlorantraniliprole were harmless for larvae and adults of C. montrouzieri. Cyantraniliprole was slightly harmful on larvae and moderately harmful on adults of C. montrouzieri at 1x. Our data suggest that buprofezin, pyriproxyfen and chlorantraniliprole could be compatible with the natural enemies evaluated, while thiacloprid and acetamiprid were less compatible with parasitoids than with the predator. Finally, cyantraniliprole seems to be less compatible than chlorantraniliprole at 1x with the natural enemies evaluated.

Sublethal Effects of Insecticides on the Parasitism of Acerophagus flavidulus (Hymenoptera: Encyrtidae) Parasitoid of the Obscure Mealybug, Pseudococcus viburni (Hemiptera: Pseudococcidae)

“…Three insecticides of different groups, widely used in deciduous fruits, were tested on the encyrtid parasitoid A. flavidulus. It has been reported that IGRs at the label rate are slightly harmful to A. flavidulus [24]. Nevertheless, in this study, the parasitism rate was not affected by buprofezin, but it was reduced with residues of pyriproxyfen at the highest mealybug density evaluated.…”

“…The neonicotinoid insecticide, acetamiprid (Hurricane 75 WP, Anasac, Santiago, Chile), applied at 0.005× of the label rate (0.6 mg•L −1 ) to control P. viburni on apples, was tested too. These concentrations were defined as "sublethal" concentrations in previous studies [24]. The residual route of exposure was selected because it tries to simulate the contact of the parasitoids after an insecticide spraying with the insecticide residues on leaf surfaces.…”

“…Management of P. viburni in deciduous fruits is based mainly on chemical control. Broad-spectrum neurotoxic insecticides, such as acetamiprid, and other more selective insect growth regulators (IGRs), such as buprofezin and pyriproxyfen, are frequently used in deciduous fruit crops in Chile [24]. On the other hand, biological control of P. viburni is associated with predators (e.g., Coccinellidae and Chrysopidae) and parasitoid wasps (e.g., Encyrtidae) [25][26][27].…”

“…Therefore, to develop effective IPM strategies, using both natural enemies and selective insecticides, the secondary effects of the latter on natural enemies must be considered [33][34][35]. In particular, it is very difficult for biological control to be compatible with the existing chemical control of obscure mealybug on deciduous fruit trees [24]. Thus, it is relevant to establish how long it would be necessary to wait for the inundative release of parasitoids after insecticide spraying.…”

Parasitic wasps (Hymenoptera) and Biological Control in Chile: Applications and Potentials

“…Curculionidae) (Zúñiga, 1985). La introducción de este tipo de controladores biológicos ha continuado, siendo en las primeras décadas del siglo XXI una práctica extendida y frecuente (Williams & Polaszek, 1996;Radrigan et al, 2021). Desde entonces, la incorporación de controladores biológicos exóticos se ha expandido exponencialmente hasta las últimas décadas, principalmente a través de la importación desde Estados Unidos (Rojas, 2005;Barra-Bucarei et al, 2020).…”