Genetic variation among drosophila melanogaster isofemale lines influences encapsulation ability of the parasitoid asobara tabida

One of the most important factors which affect the outcome of the host-parasite interactions is the genetic variation in particular those of the host. The aim of this study was to test the effect of variation within Drosophila melanogaster population on the encapsulation ability against the parasitoid Asobara tabida. To this end, nine isofemale lines of D. melanogaster which represent different levels of encapsulation ability were used. The encapsulation ability and its related parameters such as infestation, avoidance, and parasitism success and super-parasitism rates were assessed following oviposition. Larval weight, protein contents and phenoloxidase in extremes and intermediate lines, were investigated. The variation among D. melanogaster lines influenced encapsulation, avoidance, parasitism and super-parasitism rates. Upon emergence, low success of the parasitoid associated with high mortality rates were observed in the representative lines. Although parasitized larvae may suffer from weight loss, they could survive based on mounting effective immune response. Parasitism of A. tabida in the Drosophila larvae induced high phenoloxidsae activity, particularity in the resistant ones refelecting their immune competency. In sum, the variation in encapsulation ability among isofemale lines demonstrates high underlying genetic variation. The data might help to design successful biological control programs and to facilitate interpretation of a similar interaction of other host-parasite model systems

Interactions of spodoptera littoralis haemocytes following injection with the entomopathogenic fungi: Beauveria Bassiana and Nomuraea Rileyi

This study compared the cellular interactions of Spodopteralittoralis haemocytes with two virulence-different entomopathogenic fungi: Beauveriabassiana and Nomuraearileyi. Using light and transmission microscopy, five types of haemocytes namely, prohaemocytes [PRs], plasmatocytes [PLs], granulocytes [GRs], spherule cells [SPs] and oenocytoids [OEs] were identified in the 6[th] instar larvae. PRs and PLs were found in the haemopoietic tissue.Intra-haemocoelic injection of blastospores induced ultrastructural alterations in the cytoplasm and nucleiof circulating haemocytes of treated larvae. Different responses were observed in the populations of haemocyte types following injection with the tested fungi. The most important changes were the decrease of the numbers of GRs aiccompanied with increase inSPs at 12-48h following injection with B. bassiana, whereas,a decrease of PLs with a commitment increase inSPs and OEs were observed at most time intervals after injection with N. rileyi. Both fungi provoked a decrease of the total number of haemocytes at 48h followed by an increase at 72h post-injection. In vivo assay showed that the GRs and PLs actively phagocytised fungal blastospores. There was a time-dependent decrease and increase in the phagocytosis activity after injection of B. bassiana and N. Rileyi, respectively .In B. bassiana-injected insects, the numbers nodules increased significantly at 6-48h in comparison with the controls post-injection. In N. rileyi-injected insects, nodules increased significantly only at 72h post-injection.No cellular encapsulation was observed in any of the examined insects