SEASONALLY CONTRASTING ACTIVITY OF AFRICAN BLACK BEETLE, HETEROMYCHUSARATOR (COLEOPTERA, SCARABAEIDAE) - IMPLICATIONS FOR POPULATIONS, PEST STATUS AND MANAGEMENT

Flight and surface activity of the African black beetle, Heteronychus arator (Fabricius), detected by pitfall, light and window traps, was s easonally reversed. High surface activity relative to flight occurred in spring when beetles were mature, while relatively higher levels of flight occurred in autumn when they were immature. Pitfall trap captur es were male-dominated in spring and female-dominated in autumn, and w ere a poor estimator of adult density. Light trap captures were consis tently female-dominated. Although autumn flight was dispersive and inf erred to have some role in population regulation, it was largely local ized within the usual pasture habitat of the species. Some beetles fle w into irrigated potato crops in autumn, but not specifically, as beet le abundance was consistently less than in surrounding dry pasture. Hi gh surface activity indicates spring is a strategic time for surface-a pplied control measures to prevent increase of H. arator in the next g eneration, a less disruptive alternative to conventional soil-incorpor ated insecticide directed at the new generation's larvae in summer. Su ch an approach would be best aimed early in the upsurge of activity, a s most of the season's cohort of eggs was laid by the time surface act ivity peaked in mid-spring.