Fitness costs to Helicoverpa armigera after exposure to sub-lethal concentrations of Metarhizium anisopliae sensu lato: Study on F1 generation

• Metarhizium anisopliae is virulent to Helicoverpa armigera.
• M. anisopliae affects biological parameters of offspring from treated larvae of H. armigera.
• rm value decreased in female moths developed from M. anisopliae-treated larvae of H. armigera.

The entomopathogenic fungus, Metarhizium anisopliae (Metsch.) Sorokin is a valuable biocontrol agent attacking larval stages of many lepidopteran pests including Helicoverpa armigera (Hübner). Sub-lethal effects of M. anisopliae sensu lato (s.l.) (isolate M14) were investigated on life table parameters of offspring from treated larvae of H. armigera. Duration of different life stages was significantly affected by fungal treatments. Fecundity was decreased in females derived from H. armigera larvae treated with M. anisopliae s.l. Sub-lethal concentrations of the entomopathogen reduced the net reproduction rate (R0) of F1 insects for all treatments compared with the control. Similar reductions were observed for the intrinsic and the finite rates of increase (rm and λ, respectively). The mean generation time (T) and the doubling time (DT) were statistically higher in offspring of individuals exposed to some fungal concentrations than control insects. Our results indicated that there was a significant decrease in the F1 population of H. armigera derived from larvae that were exposed to sub-lethal concentrations of M. anisopliae s.l.

Age-specific survivorship (lx) and fecundity (mx) of offspring derived from M. anisopliae s.l.-treated third instar Helicoverpa armigera. (a) Control, (b) LC5, (c) LC10, (d) LC15, (e) LC20 and (f) LC25.Figure optionsDownload as PowerPoint slide