Selective toxicity of pyrethroid insecticides to arthropod natural enemies and pests of agricultural crops

Abstract

Data on the toxicity and selectivity of synthetic pyrethroids (SPs) to arthropod natural enemies and their host or prey are reviewed with emphasis on cotton, apple, alfalfa, cereal and vegetable inhabiting species. Generally, SPs are variably toxic and selective (in relation to their hosts or prey) to species within most families of natural enemies. Exceptions are low to moderate toxicity and favorable selectivity to most hemipteran predators, and high toxicity and unfavorable selectivity to virtually all phytoseiid mites in comparison to their prey. In North America, SPs are more favorably selective to cotton natural enemies over their prey or host than to apple inhabiting species. These differences may be due to intrinsic levels of susceptibility (preselection levels) between the types of natural enemies exploited on both crops in IPM programs (i.e. hemipteran species on cotton versus phytoseiid mites on apple) and/or to tolerances or resistances differences due to previous patterns of chemical use on these crops. Possible means of increasing selective use of SPs in future IPM systems based on ecological and physiological selectivity including the development of SP-resistant predators are discussed.Synthetic pyrethroids (SPs) are broadspectrum insecticides developed in the late 1970s which control a variety of arthropod pests (ELLIOrr, 1977). Their environmental stability plus low mammalian and high insect toxicity at rates 10-100 times less than other insecticides, make then highly attractive for use on many crops.With integrated pest management (IPM), the desired properties of insecticides have changed appreciably over the past decade (METCALF, 1980; CROFT, 1981). More complete assessment of effects on the entire species complex of the crop, including natural enemies becomes critical. On crops where a single pest predominates [e.g., olive scale, Parlatoria oleae (COLVEE), on olive], species-specific or simple (versus compound) selectivity between a naural enemy and its prey or host may be sufficient for IPM purposes. However, for the major crops (i.e., cotton, soybeans, corn, rice, apples, citrus, etc.), management of large complexes of pests and natural enemies is necessary, but seldom does any chemical have an ideal toxicity spectrum (i.e., provides compound species selectivity). Usually, chemicals are regarded as suitable for IPM, if there are overall cost-(1) Published as journal article 9920, Michigan Agricultural Experiment Station.

Pesticide selectivity for the insect egg parasitoid Telenomus remus

“…beta-cyfluthrin) were harmful to T. remus adults probably because they are neurotoxins that act similarly on all kinds of insects, beneficial and pest species. Various insecticides in this group have been reported as harmful to beneficial arthropods (Croft 1990;Croft and Whalon 1982;Sterk et al 1999).…”

Potential for Integrating Eleven Agricultural Insecticides with the Predatory Bug <I>Pristhesancus plagipennis</I> (Hemiptera: Reduviidae)

“…The pyrethroids also vary in their toxicity to various hemipteran predators. Most pyrethroids are considered to be of low to moderate toxicity to predatory bugs (Croft and Whalon 1982) and compared with other insecticides, they are generally less harmful to predatory bugs than to their pest insect prey (Wesley and Radcliff 1976, Wilkinson et al 1979, Price et al 1980. In our study, cypermethrin was an exception to this trend, because it had a low LC 50 but highly persistent residues.…”

Toxicity of mixtures of λ-cyhalothrin, imidacloprid and cadmium on the earthworm Eisenia fetida by combination index (CI)-isobologram method

“…λ-cyhalothrin is extensively used worldwide for agricultural pest control on corn crops, sorghum, sugarcane, etc. (Croft and Whalon, 1982) due to its higher efficiency, relatively shorter half-life in soil and lower mammalian toxicity (Narahashi, 2000). Both are considered as a replacement for the widely used organophosphorus pesticides in many countries.…”