Some studies on the population dynamics of the bread beetle stegobium paniceum (l) (coleoptera : anobiidae)

Abstract

Some aspects of the population dynamics of the bread beetle Stegobium paniceum were studied using a laboratory culture of the species. Initial density of adults was found to influence reproductive success, the number of progeny produced by paniceum females decreasing with increased adult density. Using densities ranging from 0.013 - 6.70 adult beetles/g, 0.66 beetles/g was found to be the density above which the number of progeny decreased markedly. Using different immature stages in densities from 0.33 to 40 per g, the egg stage showed the highest apparent mortality, although infertility of eggs was not taken into account. Mortality of the larval stages had little effect on the resulting adult numbers, although when larval density increased above 8.33 per g the mortality rate increased. One of the main factors limiting the population increase was decreased fecundity of females due to mutual interference with oviposition. The frequency of copulation decreased when a density of 12 pairs per dish was exceeded, fecundity of females also being reduced above this density. The capacity for increase r(_c) under the experimental conditions was found to be 0.52/beetle/day with 94% of eggs being laid before the females were 8 days old and the mortality being greatest between days 10 and 16.When females were provided with antennectomised males at comparatively low densities of 0.02 and 0.06 beetles/g, the progeny per female decreased by over 50% compared to that of females provided with normal males. Antennectomised males took longer to find females and to copulate than did control males. More than 90% of the control males copulated within 15 minutes whereas only 5% of antennectomised males copulated within this time.