Factors Affecting Rearing of Clover Root Curculio (Coleoptera: Curculionidae) in Cone Containers

Abstract

A rearing technique for clover root curculio, Sitona hispidulus (F.), was developed using legumes growing in cone containers in the growth chamber. Eight factors were tested for their effect on rearing clover root curculio from egg to adult: (1) sterilization of egg surfaces, (2) egg infestation rate, (3) egg age, (4) plant growth media, (5) plant age at time of infestation, (6) watering schedule, (7) legume species and infestation rate with eggs or larvae, and (8) number of holes for infesting plants with larvae. The four most important factors for improving larval growth and survival of adults were as follows: (1) egg infestation rate, (2) egg age, (3) sterilization of egg surfaces with either laundry bleach or ethanol or both followed by a sterile water rinse, and (4) a peat-vermiculite mixture as a plant growth medium. Legume species (white clover [Trifolium repens L.] , red dover [T pratense L.] , and alfalfa [Medicogo sativa L.]) , watering schedules (two, three, or seven times a week), and number of holes for placing larvae in the soil had little or no impact on survival. Survival was improved by using eggs rather than larvae to infest plants. Five or more eggs per plant increased abnormalities in adults. Usually, insect survival was reduced with increasing number of eggs (10 or more per plant). Taproot injury increased with increasing numbers of eggs, but not larvae, per plant. There was 30-50% recovery of males and females. Previously published methods reported only a maximum of =20% survival from egg to adult.