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ARS Home » Pacific West Area » Maricopa, Arizona » U.S. Arid Land Agricultural Research Center » Pest Management and Biocontrol Research » Research » Publications at this Location » Publication #334221

Research Project: Ecologically Based Pest Management in Western Crops Such as Cotton

Location: Pest Management and Biocontrol Research

Title: Comparative toxicities of newer and conventional insecticides against four generalist predator species

Author
item PRABHAKER, NILIMA - University Of California
item Naranjo, Steven
item PERRING, THOMAS - University Of California
item Castle, Steven

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/26/2017
Publication Date: 12/1/2017
Publication URL: http://handle.nal.usda.gov/10113/5922767
Citation: Prabhaker, N., Naranjo, S.E., Perring, T., Castle, S.J. 2017. Comparative toxicities of newer and conventional insecticides against four generalist predator species. Journal of Economic Entomology. 110(6):2630-2636.

Interpretive Summary: Beneficial insects in crops include a large contingent of predatory insects that feed on other insects including pest species. Predatory insects in Arizona crops feed generally on many species but have been shown to play a vital role in controlling whitefly populations. It is therefore essential to conserve predators and encourage their activities at combating whiteflies. However, predators and other beneficial insects are threatened each time an insecticide spray is applied to a crop. The potential damage to beneficial insects caused by insecticide applications can be ameliorated by using compounds that are selectively active against the targeted pest, yet relatively less toxic to beneficial insects. To improve knowledge of the relative toxicities of various insecticides on predatory insects, a laboratory study was conducted to evaluate the impact that eleven different insecticides have on four species of predators. Highest toxicities were observed with imidacloprid and clothianidin against small immatures of the big-eyed bug (Geocoris punctipes). The pyrethroid insecticide bifenthrin was highly toxic against adults of the big-eyed bug and the minute pirate bug (Orius insidiosus), but less so to the ladybird beetle (Hippodamia convergens). Four insecticides including pyriproxyfen, buprofezin, spirotetramat, and spiromesifen caused only moderate to low mortality against all four predators and therefore should be considered in IPM programs that practice conservation of beneficial insects.

Technical Abstract: Generalist insect predators play an essential role at regulating populations of Bemisia tabaci and other pests in agricultural systems, but face depredations due to insecticide applications. Evaluation of insecticide compatibility with specific predator species can provide a basis for making treatment decisions with the aim of conserving natural enemies. Eleven insecticides representing six mode of action groups were evaluated for toxicity against four predator species. Full-dose bioassays were conducted on laboratory-reared or insectary-supplied predators using Petri-dish and systemic uptake bioassay techniques. Highest toxicities were observed with imidacloprid and clothianidin against first and second instar nymphs of Geocoris punctipes (Say). Later instar nymphs were less susceptible to neonicotinoid treatments based on higher LC50s observed with imidacloprid, thiamethoxam, and dinotefuran against third or fourth instar nymphs. The pyrethroid insecticide bifenthrin was highly toxic against adults of G. punctipes and Orius insidiosus (Say), less so to Hippodamia convergens Guérin-Méneville. Standard dose/mortality evaluation of non-acute toxicity insecticides including buprofezin, pyriproxyfen, spirotetramat, and spiromesifen proved inconclusive in terms of generating probit statistics. However, low mortality levels of insects exposed for up to 120 h suggested minimal lethality with the exception of pyriproxyfen that was mildly toxic to Chrysoperla rufilabris (Burmeister).