Movement Ecology of the Red Milkweed Beetle in Relation to Population Size and Structure

Publisher Website
Google Scholar
Abstract
(1) The population biology of the milkweed beetle Tetraopes tetraophthalmus was studied for 3 years using mark-release-recapture methods within six host-plant patches differing in size, plant density, and degree of isolation. Beetle abundance, but not beetle density per plant, was correlated with host-plant patch size. (2) Beetle sex ratios differ between days and between patches, changing the relative abundance of potential mates within and between subpopulations. (3) Male residency is less than female residency. The average age of males, however, is significantly greater than females. This results from males 2-6 days old being underrepresented in the population. (4) Males move significantly farther between recaptures than females both within and between host-plant patches. Males also move between host-plant patches significantly more frequently than females. The sexes exhibit different age-dependent movement; males obtain high levels of mobility much more rapidly than females. The age of individuals moving between patches is significantly greater than that of individuals moving within patches. Different age-dependent patterns of movement, not maximal movement capabilities, explain observed differences in male and female mobility. (5) Different factors influence male and female rates of residency, immigration, emigration, and disappearance. Males are particularly responsive to sex ratio and conspecific abundance, leaving patches where sex ratios are male biased.