Insecticide survival and behavioral avoidance in the lacewings Chrysoperla externa and Ceraeochrysa cubana

Abstract

Insecticide impact on non-target species, such as insect predators and parasitoids, is an ever-growing concern in agriculture and recent studies have been shifting focus from lethal to sub-lethal effects since they may prevail in field conditions, although more difficult to assess. Synthetic insecticides are the main concern, but the recent spread of biopesticide use in agriculture draws attention, particularly the main botanical insecticide currently in use - azadirachtin. Here we assessed the lethal and behavioral sub-lethal response of predatory larvae of the lacewing species Chrysoperla externa and Ceraeochrysa cubana to two frequently used synthetic insecticides, malathion and permethrin, and to the bioinsecticide azadirachtin. The recommended field concentration of the synthetic insecticides led to low survival time of lacewing larvae from both species, in contrast with azadirachtin. However, all three compounds led to 100% mortality of the lacewing larvae from both species. Insecticide repellence (i.e., avoidance without contact) was similar for both synthetic insecticides in both species, but azadirachtin was a stronger repellent for C. externa, but not C. cubana. In addition, insecticide irritability (i.e., avoidance after contact) occurred in both lacewing species to all three insecticides tested. The notion that natural compounds are safer than synthetic compounds to non-target species is refuted in the present study, which also detected significant irritability to all of the insecticides regardless of their origin, and species-specific repellence elicited particularly by azadirachtin. Therefore, bioinsecticides should not be exempted from risk assessment, and non-target sub-lethal effects should not be neglected when considering potential insecticide use in agriculture.

Mating behavior of the predator Podisus nigrispinus (Heteroptera: Pentatomidae) under exposure to neem: Comportamiento de apareamiento del depredador Podisus nigrispinus (Heteroptera: Pentatomidae) expuesto al neem

“…The frequency of mating did not differ significantly, with values from 1.4 to untreated male and female, untreated male and treated female and treated male and untreated female and 1.5 to treated male and female (Kruskal-Wallis test, χ 2 = 0.55, df = 3, p = 0.91). Although selectivity of insecticides to natural enemies is often determined with bioassays of mortality (Preetha et al, 2010), they can also be involved in a variety of morphological, physiological, reproductive, and behavioral effects (Cordeiro et al, 2010). In agreement with this work, which was observed that exposure of the predator P. nigrispinus azadirachtin interferes with the mating behavior.…”

Survival and behavioural response to acaricides of the coconut mite predator Neoseiulus baraki

“…The acaricide was considered a repellent when the mite did not invaded the treated hemisphere basically remaining the whole time on the untreated hemisphere. The acaricide was considered to cause irritability when the mite moved to the treated hemisphere, but remained there less than 50 % of the total time (Cordeiro et al 2010). …”

“…To reduce contact with these products, predators may use behaviours that facilitate escape from sprayed environments. These behaviours can cause changes in locomotion, thereby causing irritability or even repellence (Davidson 1953;Robertson and Preisler 1992;Pothikasikorn et al 2007;Cordeiro et al 2010). Irritability occurs when an insect is stimulated to move away from an insecticide after making direct physical contact with the chemical residue, whereas repellence occurs when the insect detects chemicals from a distance, and is diverted out of the treated area without making direct physical contact with the chemical (Roberts et al 1997).…”

Toxicity of neem oil to the cassava green mite Mononychellus tanajoa (Bondar) (Acari: Tetranychidae)

“…Non-lethal concentrations of pesticides affects physiology and behavior of arthropods causing, for instance, reduction of fertility, foraging interference, repellence, feeding deterrence, changes in biological parameters, morphological abnormalities, interferences in foraging behavior, and reduced growth rate (Teodoro et al, 2005;Kim et al, 2006;Marcic, 2007;Desneux et al, 2007;Teodoro et al, 2009;Cordeiro et al, 2010).…”