INFLUENCE OF Botrytis cinerea ON PARASITOID ATTACK
RATIO IN THE FIELD
1Yahaya, S.M. and 2Fellowes, M.D.E.
1Department of Biology, Kano University of Science and Technology, Wudil, Kano State, Nigeria
2School of Biological Sciences, University of Reading, RG6 6AS, United Kingdom
E-mail: sanimyahya@yahoo.com
ABSTRACT
Effects of infection during parasitoids host choice are ubiquitous, yet we have little understanding of how the presence of a systemic pathogen Botrytis cinerea may affect field interactions at higher trophic levels. Interactions between the peach potato aphid Myzus persicae Sulzer (Hemiptera: Aphididae) and its common parasitoid, Aphidius colemani Vierek (Hymenoptera: Braconidae), were investigated in the field which is less controlled environment to determine if these are influence by infection of the host aphids (lettuce Lactuca sativa, L. asteraceae: Compositae) by the widespread plant pathogen Botrytis cinerea. While field experiment showed that females parasitoids are generally larger than males, which may be due to the results of sex–specific allocation of offspring to host of higher and lower food value and the sex specific exploitation of host resources. More parasitoid mummies were recorded on uninfected plants than infected ones which were similarly reported in the controlled environment. The field experiment showed the effect of infection on parasitoid sex ratio (F1, 49 = 77. 533, P< 0.001) as a greater proportion of the A. ervi collected from hosts reared on uninfected plants were female, while same ratio was found from infected plants with overall offspring sex ratio of 62.2% females and 37.7% males. Therefore, the observations of the field experiment provide further evidence that hidden, systemic host plant infection by B. cinerea influences the interaction between aphids and their parasitoids.