Reactions of the Three-Lined Potato Beetle, Lema trilineata (Coleoptera: Chrysomelidae), to Its Host and Certain Nonhost Plants

Abstract

The mechanisms of host-plant selection pertaining to phytophagous insects have been widely studied, but investigations have been limited principally to those insects damaging valuable crop plants. It is suggested that host-selection habits of weed-feeding insects be studied also, since the latter are certainly of economic importance. The feeding and oviposition behavior of the three-lined potato beetle, Lema trilineata (Olivier), was studied. Normally the host plants of this insect, an oligophagous chrysomelid, are solanaceous plants of the genus Datura . Larvae attempted to feed on any solanaceous or non-solanaceous plant offered even though some plants were toxic and others unsuitable for larval growth and development. Adults were more fastidious in selecting hosts for feeding and oviposition. Neither larvae nor adults responded to synthetic nutrient or nonnutrient diets containing Datura leaf extracts or leaf powder as readily as they responded to a fresh leaf. All evidence indicated that the feeding behavior of this insect is conditioned by a combination of factors in the food medium. Adult beetle feeding and oviposition behavior in several types of cages showed that the insect is influenced more by the physical environment within the cage than by its size or shape. These studies pointed out the need for additional basic research into plant-insect relationships for a better understanding of host-plant specificity.