Studies on the Biology and Host Location Behavior of Pteromalus cerealellae (Ashmead) (Hymenoptera: Pteromalidae), A Parasitoid of Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae)
Type of DegreeDissertation
Entomology and Plant Pathology
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Pteromalus cerealellae is an ectoparasitoid of several pests of stored products. Information on several aspects of its biology and life history strategy is grossly lacking. My dissertation focuses on some aspects of the biology, behavior and the cues used by P. cerealellae to locate its host, Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae). In Chapter II, I investigated the influence of environmental factors on longevity and reproductive performance of P. cerealellae. Male and female wasps benefited greatly from sugar feeding with significant increases in lifespan and progeny production. The suitability of freeze-killed larvae of C. maculatus as hosts for rearing P. cerealellae was investigated in Chapter III. Live and freeze-killed C. maculatus larvae were equally suitable as hosts for P. cerealellae with no significant difference in progeny production. In Chapter IV, I characterized the pre-imaginal stages of P. cerealellae for the first time using morphological structures revealed by microscopic techniques and recorded four larval instars for P. cerealellae. The external morphology of antennal sensilla of P. cerealellae was examined in Chapter V using scanning electron microscopy. Three morphologically different olfactory sensilla types were recorded on the antennae of both sexes with major sexual differences in the abundance of the multiporous sensilla trichodea type III and the multiporous placoid sensilla. In Chapter VI, I documented the mating behavior of P. cerealellae. Females exhibit “calling behavior” to initiate courtship. Males play the active role, exhibiting most of the observed pre-mounting behaviors. The role of semiochemicals in mediating intraspecific communication in P. cerealellae was investigated in Chapter VII using electroantennogram (EAG), behavioral (olfactometer) and analytical (gas chromatography) techniques. Results suggest the existence of male- and female-produced semiochemicals, possibly of cuticular origin, in this species. In Chapter VIII, the role of host-related semiochemicals in the host location of P. cerealellae was investigated using EAG, behavioral and analytical techniques. Results suggest the use of multiple olfactory stimuli in host finding by female P. cerealellae with preference for stimuli from host habitats (cowpea seed odor).