INTRASPECIFIC COMPETITION BY THE COLORADO POTATO BEETLE (COLEOPTERA, CHRYSOMELIDAE) ON POTATO PLANTS, SOLANUM-TUBEROSUM

The aim of this study was to measure the effects of an increase in the density of the Colorado potato beetle, Leptinotarsa decemlineata (Say ), an this insect. Two groups of 20 potato plants, Solanum tuberosum L ., 'Superior', were subjected to defoliation by the Colorado potato be etle. The first group was infested by 15 larvae per plant and the seco nd by 40 larvae per plant. Measurements of adult body weights were tak en, as well as of the quantity of lipid reserves of adults collected u pon emergence. Insects originating from plants infested by 15 larvae w ere significantly heavier and had accumulated significantly more lipid reserves than adults originating from plants infested by 40 larvae. T he percentage of lipids over body weight was significantly lower at a density of 15 larvae per plant than at a density of 40 larvae per plan t. The effects measured in the 40 larvae per plant group are the resul t of intraspecific competition phenomena.