No abstract

Mortality of agricultural pests caused by arthropod predators is a valuable ecosystem service for crop production. The earwig, Euborellia annulipes (Lucas), attacks different pest species in various crop ecosystems, including larvae and pupae of the boll weevil, Anthonomus grandis grandis (Boh.). Despite such biological control, cotton pest management remains heavily dependent on synthetic insecticides. In this study, multiple factors were assessed to measure the selectivity of insecticides used against sapsucking and chewing cotton pests for two E. annulipes populations. Nymphs and adults of E. annulipes were exposed to the insecticides in two ways: ingestion of contaminated prey, and contact with dried residues on either inert surfaces or treated plants bearing prey. Pymetrozine, chlorantraniliprole, and spinetoram had little effect on the predator regardless the tested earwig population, life stage, or the route of exposure. Cyantraniliprole affected the predator in some life stages and through some types of contact. Pyriproxyfen was harmless to adult earwigs, but prevented normal development of nymphs to adults. Chlorfenapyr, indoxacarb, lambda-cyhalothrin, chlorpyrifos, dimethoate, and malathion were harmful to the predator regardless earwig life stage or method of exposure. The negative impact was diminished when exposure occurred on plants with predator allowed to shelter in the soil. The results indicate that insecticide selectivity outcome is a multi-factor driven by the insecticide, predator life stage and the redator's behavior. Therefore, testing different predator life stages via several routes of exposure, without denying the insect the opportunity to engage in its normal behaviors can provide better estimates of insecticide selectivity.

No abstract

Synthetic insecticide application is one tactic for reducing boll weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), infestations during the cotton, Gossypium hirsutum L., reproductive stage. We assessed the susceptibility of the boll weevil and its natural enemies to ethiprole (mode of action 2B), a phenylpyrazole insecticide, and diagnostic concentrations of ethiprole indicative of boll weevil susceptibility. Differences in the lethal concentrations of ethiprole were calculated with susceptibility ratios based on LC50 ranging from 2.89- to 10.34-fold relative to a natural susceptible population. The lowest and the highest recommended field rates of ethiprole, 100 and 200 g a.i./ha, produced residues that caused 83.3% and 93.7% mortality of weevils caged with cotton leaves from field-treated plants for 8 d. We found that ethiprole was less toxic than fipronil to the boll weevil parasitoid Bracon vulgaris Ashmead (Hymenoptera: Braconidae) and to the red imported fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae), while fipronil was highly toxic to both. Adult earwigs, Euborellia annulipes Lucas (Dermaptera: Anisolabididae), were relatively tolerant to ethiprole and fipronil at the highest field rates. Pooled LC50-and LC95-concentrations of ethiprole calculated from studied populations were used as diagnostic for boll weevil mortality, and the outcome fitted to the expected mortality for boll weevil populations from different locations serving for further control failure assessment. Ethiprole appears to be suitable for boll weevil control with low impact on natural enemy communities.

No abstract

No abstract

Mortality of agricultural pests caused by arthropod predators is a valuable ecosystem service for crop production. The earwig, Euborellia annulipes (Lucas), attacks different pest species in various crop ecosystems, including larvae and pupae of the boll weevil, Anthonomus grandis grandis (Boh.). Despite such biological control, cotton pest management remains heavily dependent on synthetic insecticides. In this study, multiple factors were assessed to measure the selectivity of insecticides used against sap-sucking and chewing cotton pests for two E. annulipes populations. Nymphs and adults of E. annulipes were exposed to the insecticides in two ways: ingestion of contaminated prey, and contact with dried residues on either inert surfaces or treated plants bearing prey. Pymetrozine, chlorantraniliprole, and spinetoram had little effect on the predator regardless the tested earwig population, life stage, or the route of exposure. Cyantraniliprole affected the predator in some life stages and through some types of contact. Pyriproxyfen was harmless to adult earwigs, but prevented normal development of nymphs to adults. Chlorfenapyr, indoxacarb, lambda-cyhalothrin, chlorpyrifos, dimethoate, and malathion were harmful to the predator regardless earwig life stage or method of exposure. The negative impact was diminished when exposure occurred on plants with predator allowed to shelter in the soil. The results indicate that insecticide selectivity outcome is a multi-factor driven by the insecticide, predator life stage and the redator’s behavior. Therefore, testing different predator life stages via several routes of exposure, without denying the insect the opportunity to engage in its normal behaviors can provide better estimates of insecticide selectivity.