Effect of Light Intensity on the Colony Development of <i>Lasius japonicus</i>（Hymenoptera: Formicidae）

Abstract

In this study, we examined the effect of light intensity on colony development regulation in Lasius japonicus Santschi. Queens were collected soon after their nuptial flight in Okayama, Japan. They were reared under 16L-8D（16 h light, 8 h dark）and 12L-12D at 25°C with four light intensity conditions: 50, 200, 800, and 3000 lux. The queens started oviposition soon after collection. Thereafter, the larvae, pupae, and workers emerged under the 50–800 lux conditions； however, the hatching and larval development were suppressed under 3000 lux conditions, especially under the long-day photoperiod. Light intensity was also measured under the shelters where queens were found soon after their nuptial flight. Under the shelters, the median light intensities were between 2.4 lux and 1070.5 lux, which was low enough for the queens to develop colonies. These results suggest that queens start colony founding at places with low light intensity. The queens also likely control the rate of colony development by responding to the light intensity of the surrounding environment.