Larvicidal activity of Trichoderma atroviride (Hypocreales: Hypocreaceae) against Aedes albopictus (Diptera: Culicidae)

Abstract

Larviciding is an important part of effective integrated mosquito management. However, growing resistance to chemical and bacterial-based insecticides requires biocontrol agents with novel modes of action. Entomopathogenic fungi are good candidates for larval control due to their capability to infect mosquito larvae and their production of larvicidal compounds. In this study, we isolated a strain of Trichoderma atroviride from Aedes albopictus larvae collected in Manhattan, KS, USA. We used a laboratory-based microcosm assay to expose L3 Ae. albopictus larvae to T. atroviride conidia and culture supernatant treatments. Larvae were monitored daily for survival and development to pupae and adults. In addition, adult survival was monitored for ten-days post pupation, and wing lengths were measured to assess mosquito size. Our results revealed that T. atroviride culture supernatant was a potent larvicide towards Ae. albopictus. However, conidia by themselves were not larvicidal, indicating the major mode of killing was through toxicity exerted by the culture supernatant. We further showed that larval exposure to T. atroviride supernatant delayed larval development to pupae. Sex-specific adult survival was not affected by larval exposure to T. atroviride. However, wing length of male and female mosquitoes were reduced, indicating a reduction in adult mosquito body size as compared to the control. Taken together, this study identifies the culture supernatant from a novel strain of T. atroviride as a potent larvicide of Ae. albopictus, potentially expanding our toolbox for biological control of mosquitoes.