Lecanicillium attenuatum infection and effects on the reproduction of Frankliniella occidentalis

Abstract

ABSTRACT Frankliniella occidentalis, western flower thrips, is an invasive pest that seriously damages economic crops such as vegetables, flowers, and fruit trees because of its high fecundity, short generation cycle, and strong adaptability. Lecanicillium is an important entomopathogenic fungus, characterised by its wide host range, high pathogenicity, and environmental safety. It plays an important role in the environmentally friendly management of F. occidentalis. This study clarifies whether L. attenuatum infects F. occidentalis and affects its reproduction. The results of scanning electron microscope showed that conidia of L. attenuatum were attached to many parts of thrips adult after 1 h of treatment with 10^8 conidia/mL, and most F. occidentalis were covered by hyphae after 72–120 h. The cumulative mortality rate of the second instar larvae of the F1, F2, and F3 generations exceeded 60% on the seventh day post-infection and that of female adults was higher than 90% when treated by L. attenuatum with 10^8 conidia/mL. Simultaneously, L. attenuatum had strong sublethal effects on the surviving thrips. Indeed, the number of eggs deposited and the lifespan of female adults decreased considerably after the second instar larvae of F. occidentalis were treated with L. attenuatum, and had the impaction on the thrips offspring too. Altogether, our data suggested that L. attenuatum not only exhibited a high degree of pathogenicity towards F. occidentalis second instar larvae and adults but also affected the longevity and reproduction of surviving thrips.