Potential biocontrol services by seven aphid predators for the control of Aphis nerii infesting Mandevilla

Abstract

Aphids are an important economic pest in protected crops and, among them, Aphis nerii Boyer de Fonscolombe is considered a key pest of the ornamental Mandevilla plant. This aphid can produce damage that can severely reduce the aesthetic and commercial value of ornamental plants. For the development of successful biological control strategies, information on prey suitability and predator’s functional response is essential. In this study, we first evaluate the suitability of A. nerii as a food source for seven commercial generalist predators, as well as their ability to suppress aphid population. The tested predator species were: Chrysoperla carnea Stephens (Neuroptera: Chrysopidae), Sphaerophoria rueppellii Wiedmann (Diptera: Syrphidae), Episyrphus balteatus DeGeer (Diptera: Syrphidae), Micromus angulatus Stephens (Neuroptera: Hemerobiidae), Propylea quatuordecimpunctata L. (Coleoptera: Coccinellidae), Adalia bipunctata L. (Coleoptera: Coccinellidae), and Sympherobius fallax Navas (Neuroptera: Hemerobiidae). Then, we assessed the predation rates and the functional response of C. carnea, M. angulatus, and P. quatuordecimpunctata preying on A. nerii. The first two experiments demonstrated that M. angulatus, P. quatuordecimpunctata, and S. rueppellii can survive, develop, and reproduce on A. nerii. Aphis nerii resulted in unsuitable prey for the remaining predators, as they displayed low foraging efficiency, survival and negligible impact on aphid population density. From the functional response study, it was observed that C. carnea did not show a significant response to varying densities of A. nerii. In contrast, both M. angulatus and P. quatuordecimpunctata exhibited a Type II functional response. Among these, the brown lacewing (M. angulatus) demonstrated superior predatory efficiency, with a higher attack rate and a shorter handling time compared to the lady beetle (P. quatuordecimpunctata). Although further studies are needed to understand the complex predator–prey dynamics, this study identifies promising candidates as biological control agents of A. nerii.