Development, Oviposition, and Mortality of <I>Neoseiulus fallacis</I> (Acari: Phytoseiidae) in Response to Reduced-Risk Insecticides

Abstract

Eight reduced-risk insecticides (acetamiprid, thiamethoxam, imidacloprid, thiacloprid, methoxyfenozide, pyriproxyfen, indoxacarb, and spinosad) and three conventional insecticides (azinphosmethyl, fenpropathrin, and esfenvalerate) were tested against Neoseiulus fallacis (Garman) (Acari: Phytoseiidae), the most abundant predacious mite in North Carolina apple (Malus spp.) orchards. To assess the effect of insecticides on development and mortality of N. fallacis immatures, 12-h-old eggs were individually placed on bean leaf disks previously dipped in insecticide solutions. Tetranychus urticae Koch (Acari: Tetranychidae) females were added as a food source. None of the reduced-risk insecticides significantly affected immature N. fallacis compared with the control; however, the pyrethroids esfenvalerate and fenpropathrin were highly toxic to immatures. To evaluate the effect of insecticides on mortality and oviposition of adult N. fallacis, 7- to 8-d-old females were confined on insecticide-treated bean leaves with Malephora crocea (Aizoaceae) pollen added as a food source. Spinosad resulted in the highest mortality, whereas azinphosmethyl, acetamiprid, fenpropathrin, and imidacloprid were moderately toxic, and mortality from esfenvalerate, indoxacarb, thiacloprid, methoxyfenozide, pyriproxyfen, and thiamethoxam did not differ significantly from the control. Oviposition was affected in a similar manner, with the exception of acetamiprid that did not affect oviposition, and thiamethoxam that reduced oviposition.

Beyond Focal Pests: Impact of a Neonicotinoid Seed Treatment and Resistant Soybean Lines on a Non-Target Arthropod

“…With regard to phytoseiid mites, some research has shown that these chemicals were not directly toxic [42,43,44,67] and others have found negative effects on survival, either by direct exposure or via residues or contaminated prey [38,68]. Adverse effects of consuming neonicotinoid-tainted spider mites have been noted for several predators, and include: higher mortality, reduced mobility, lower feeding rates, and/or reduced fecundity [34,42,43]. There is also evidence that neonicotinoids alter aspects of predator life history (e.g., fecundity), movement, and prey consumption [42,43,44,63,67].…”

“…Adverse effects of consuming neonicotinoid-tainted spider mites have been noted for several predators, and include: higher mortality, reduced mobility, lower feeding rates, and/or reduced fecundity [34,42,43]. There is also evidence that neonicotinoids alter aspects of predator life history (e.g., fecundity), movement, and prey consumption [42,43,44,63,67]. In our study, A. fallacis reproduction and the suppression of spider mites was not adversely affected on seed treated plants.…”

“…Phytoseiid mites (Acari: Phytoseiidae) are important predators of spider mites in many agroecosystems [41]. Neonicotinoids are not always toxic to phytoseiid mites [42,43,44], although this likely depends on the specific chemical, dosage, method of exposure, mite species, and life stage. In some situations, phytoseiid mites exposed to neonicotinoids had higher levels of mortality [38,42,45], reduced oviposition rates [42,44,45], and reduced prey consumption [43].…”