Development and reproduction of Lobesia botrana on vine and olive inflorescences

Abstract

Grape vine (Vilis vinifera F.) inflorescences were caged in a bag of organdy in the field, and artificially infested with 15 neonate larvae of Lohesia botrana (Denis and Schiffermueller) (Lepidoptera: Tortricidae). Olive twigs, each bearing 5 pairs of inflorescences were caged likewise. In laboratory experiments 15 neonate larvae were placed in each Petri dish containing one vine inflorescence or an olive twig bearing two pairs of inflorescences. Three stages of inflorescence development were used, an early, an intermediate and a late one. Larvae, pupae and adults were maintained at L:D 16:8 and 24″:22°C. In the field, when comparing inflorescences of the earliest developmental stage, the rate of larval development was significantly faster on olive than on vine inflorescences. In the laboratory, when comparing inflorescences of similar developmental stages, the rate of larval development on olive inflorescences was significantly faster than that on vine inflorescences. Pupae of both sexes were significantly heavier on olive inflorescences in all the cases in the laboratory, but in only some cases in the field. In the field the number of eggs per female and the coefficient of multiplication of the insect’s population from generation to generation were greater on olive (102.6 and 3.8 respectively) than on vine inflorescences (81.7 and 2.9). In the laboratory, the respective values were 118.5 and 12.3 on olive, and 90.2 and 4.9 on vine inflorescences. In two-choice tests in the laboratory, vine inflorescences were preferred for oviposition to olive inflorescences and to vine or olive leaves. In no-choice tests, vine leaves, vine inflorescences, olive leaves and olive inflorescences in the least advanced stage, were all equally accepted for oviposition.