Effects of the nuclear polyhedrosis virus of the Egyptian cotton leafworm, Spodoptera littoralis (Boisd.) on the Mediterranean fruit fly, Ceratitis capitata (Wied.)

Abstract

The relative activity of three concentrations of Spodoptera Uttoralis nuclear polyhedrosis virus (SLNPV) against Ceratitis capitata were determined by (a) submerging two egg age groups, freshly laid eggs (0-2.5 hr) and more older ones (0-24 hr) in viral concentrations, and (b) feeding newly hatched larvae on viral contaminated media. Pupations that resulted from all viral treatments were decreased with increase of virus dose. Hatchability showed the same relation, but hatchability of treated old eggs were not significantly influenced by increases in viral concentration. Adult emergence was significantly reduced due to viral treatments to eggs, however, it was increased in the case of feeding the larvae on contaminated diet. The most hypothetical probability of this deleterious effect may be attributed to an activation of an indigenous virus already present in C. capitata. More research is required to understand the basis for the deleterious effect of SLNPV on the fruit fly.Resume-L'activite relative de trois concentrations de la polyedrose nucleaire de Spodoptera Uttoralis (SLNPV) contre in mouche de fruits Ceratitis capitata a ete determine. Les essais ont ete effectues par la contamination des coplaques successivement pondues (0, 2.5 et 24 heures), et ralimentation des larves neonates sur milieu contamine par la suspension virale. La pupaison, pour tous les traitements viraux, diminue avec l'augmentation des doses virales. Le taux d'eclosion des oeufs montre la meme relation mais si le traitement est effectue sur des vieux oeufs il n'y a pas d'influence significative selon les augmentations des doses virales. La sortie des adultes est reduite d'une facon significative par le traitement des oeufs, mais surtout dans le cas ou les larves sont nourries sur du milieu contamine. II est suggere comme hypothese que l'effet deletere est attribue a une activation d'un virus deja present dans Ceratitis capitata. D'autres recherches sont necessaires pour comprendre l'effet deletere de SLNPV sur la mouche des fruits.