Differential Responses of Ceratitis Capitata to Infection by the Entomopathogenic Fungus Purpureocillium Lilacinum.

Abstract

Ceratitis capitata (medfly), is one of the most injurious pests of fruits with quarantine importance because of its extremely wide host range. The use of entomopathogenic fungi constitutes a promising approach for potential applications in integrated pest management. Nonetheless, developing methods of insect control can also involve the use of fungal machinery to produce metabolic disturbance that can increase its effectiveness by producing a detrimental effect on insect development. Insect species, such as Ceratitis capitata, depend on reproduction potential, nutrient reserves, metabolic activities and immune response for their survival. Accordingly, the purpose of this study is to use the entomopathogenic fungus Purpureocillium lilacinum to investigate, its sublethal effects on Ceratitis capitata. Laboratory bioassays were conducted on medfly V8 strain. The bioassays were monitored to determine the virulence of P. lilacinum on the fruit fly. P. lilacinum was tested against 5 days-old males and females, through abdominal topical applications. Following the fungal inoculation, we showed (i) a significant increase of sugar amount in tissues, (ii) a significant decrease in carbohydrase activities, digestive glycosyl hydrolase and proteinase activities in whole midguts of treated flies, (iii) an over-expression of Takeout and Attacin-A genes induced by infection. Moreover, the up-regulations observed for relish, cecropin 1, ceratotox-A and defensin genes are due to physiological mechanisms occurring during infection.