Changes in life table parameters and intermediary metabolism of Cryptolaemus montrouzieri Mulsant after infection by Beauveria bassiana

Abstract

The effects of two native isolates of Beauveria bassiana, AM-118 and BB3, were evaluated on the predatory coccinellid, Cryptolaemus montrouzieri by measuring several developmental parameters and intermediary metabolism. Treatment with both isolates significantly increased the length of each developmental stage compared to the control except for the eggs and adults. The preovipositional period in the adults treated with BB3 significantly increased compared to those treated with AM-118 and the control. Other parameters, including longevity, length of oviposition period and fecundity, showed no significant differences between treatments. Although there were no significant differences in the parameters of net reproduction rate ( R0) and gross reproduction rate ( GRR) between the control and fungal treated C. montrouzieri, the intrinsic rate of population increase ( r) and finite rate of population (λ) for the control treatments were significantly higher. The activities of both aminotransferases in the larvae and the adults treated with both isolates significantly increased 96 hours post-treatment compared to the control. Although similar results were recorded for acid phosphatase activity, alkaline phosphatase activity showed no significant differences in larvae and adults between the treatments. The amount of protein significantly decreased in the larvae and the adults treated with both isolates after 96 hours, while the amount of triglyceride significantly reduced in the treated larvae compared to control. No significant differences were observed in adults. Our results indicated that both native isolates of B. bassiana may affect life fitness of C. montrouzieri but isolate AM-118 was more compatible than BB3.

Keywords

• biology
• entomopathogenic fungi
• intermediary metabolism
• mealybug ladybird
• microbe-predator interaction