Effects of height and habitat type on egg parasitism by Trichogramma minutum and T. pretiosum (Hymenoptera: Trichogrammatidae)

• Published in: Agriculture, ecosystems & environment Vol. 12; no. 2; pp. 117 - 126
• Main Author: Thorpe, Kevin W.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 1985; Elsevier Science
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Animals; Autoecology; Biological and medical sciences; biological control; egg laying; Fundamental and applied biological sciences. Psychology; habitat; Heliothis virescens; Noctuidae; oviposition; parasitism; Protozoa. Invertebrata; Trichogramma minutum; Trichogramma pretiosum; Trichogrammatidae; Heliothis virescens; Egg; Insecta; Parasite; Entomophagous; Arthropoda; Lepidoptera; Trichogrammatidae; Vegetation; Habitat; Height; Parasitism; Invertebrata; Hymenoptera
• ISSN: 0167-8809; 1873-2305
• DOI: 10.1016/0167-8809(85)90072-6

Heliothis virescens (Fabricius) eggs were sampled to determine the effects of height and habitat type (soybean field vs. uncultivated vegetation) on rates of p arasitism by Trichogramma minutum Riley and T. pretiosum Riley. The potentially confounding effects of plant associations and host density and distribution were eliminated by sampling with laboratory-produced eggs deposited on cloths, rather than with eggs naturally deposited by endemic hosts. A 3-way contingency table analysis showed that parasitism (whether the egg cloths were parasitized or not) was significantly associated with height and habitat type in 1981, with higher rates of parasitism in the uncultivated habitat and at the greater height. Parasitism was independent of height and habitat in 1982. Rates of parasitism by the two Trichogramma species were not clearly associated with habitat type, but were associated with height. T. minutum consistently parasitized egg cloths positioned at greater heights than those parasitized by T. pretiosum. While the behavioral mechanisms responsible are unknown, this inter-specific difference could have important implications with regard to selecting the most suitable of these two Trichogramma species for a particular inundative release program.