Observations on the biology of the bronze flea beetle <i>Altica tombacina</i> (Coleoptera: Chrysomelidae) in British Columbia

Abstract

Populations of A. tombacina were monitored for 2 years at three field sites of varying elevation on Vancouver Island . In 1988, population densities of overwintered adults were greatest at the middle elevation (615m) followed by the highest (830m) and lowest at the low elevation (185m). Egg densities remained below 101m2 at 185m but exceeded 200/m2 in places at 615m and 400/m2 at 830m. Egg mortality was exceedingly high at all sites ranging from 98% at 185m, 95% at 615m and 99% at 830m; very few larvae appeared to survive. Only 2 adults were counted the following spring at the lowest elevation where eggs and larvae were exceedingly difficult to find . No life stages could be found at either of the higher elevation sites. Cold weather early in June, 1988, appeared to be responsible for this population decline. Overwintered adults of A. tombacina were also reared in the laboratory at constant temperatures of 18° and 25°C. The rate of oviposition was greater by a factor of 2 at the higher temperature. The egg-adult survival rate was approximately 15% at 25°C and there was no completed development at 18°. Each larva surviving to pupation consumed a mean of about 28mg. dry weight of leaf.