Footprints of the lady beetles Cryptolaemus montrouzieri and Tenuisvalvae notata affect their foraging behavior and predation rate

Abstract

AbstractThe lady beetles Tenuisvalvae notata (Mulsant) and Cryptolaemus montrouzieri Mulsant (both Coleoptera: Coccinellidae), are used in biological control of mealybugs in many countries, including Brazil. As individuals of these species walk on plant surfaces, they leave chemical footprints that can affect their interactions with conspecifics, as well as other coccinellid species in the same environment. Therefore, this study aimed to evaluate the effects of T. notata and C. montrouzieri footprints on both their own and each other's foraging behavior and predatory potential. Arena bioassays were conducted to evaluate the effect of the footprints on conspecifics and heterospecifics. In addition, the chemical profiles of these footprints were analyzed by gas chromatography, flame ionization detection, and mass spectrometry (GC‐FID and GC–MS). For this, extracts of footprints were obtained from a glass Petri dish where 20 adults (males or females) were allowed to walk for 24 h. Behavioral bioassays showed that both species can recognize each other's footprints. Tenuisvalvae notata females avoided areas treated with footprints of heterospecific females, whereas C. montrouzieri females were arrested on areas with footprints of T. notata females. Tenuisvalvae notata adults did not change their predation rate when exposed to the footprints of heterospecifics, but second instars had a higher predation rate on areas treated with heterospecific footprints. Second instar C. montrouzieri also had an increase in predation when exposed to footprints of heterospecifics, and females captured significantly more prey when exposed to footprints of conspecifics, whereas males' predation rate decreased when exposed to footprints of both conspecifics and heterospecifics. The chemical analyses showed that the hexane extracts of footprints were composed mainly of linear hydrocarbons, saturated and non‐saturated, from C20 to C33. The composition (qualitative and quantitative) of footprint extracts is species‐ and sex‐specific. This is the first report on the effects of footprints on the behavior of these species.