Variability in Small Hive Beetle (Coleoptera: Nitidulidae) Reproduction in Laboratory and Field Experiments

Experiments were conducted to examine how several key factors affect population growth of the small hive beetle, Aethina tumida Murray (Coleoptera: Nitidulidae). Laboratory experiments were conducted to examine effects of food quantity and temperature on reproduction of cohorts of young A. tumida adults (1:1 sex ratio) housed in experimental arenas. Daily numbers and total mass of larvae exiting arenas were highly variable within treatment. Either one or two cohorts of larvae were observed exiting the arenas. Food quantity, either 10 g or 20 g, did not significantly affect the number of larvae exiting arenas at 32A degrees C, but did at 28A degrees C; arenas provided 20 g food produced significantly more larvae than arenas provided 10 g. Temperature did not affect the total mass of larvae provided 10 g food, but did affect larval mass provided 20 g; beetles kept at 28A degrees C produced more larval mass than at 32A degrees C. Field experiments were conducted to examine A. tumida reproductive success in full strength bee colonies. Beetles were introduced into hives as egg-infested frames and as adults, and some bee colonies were artificially weakened through removal of sealed brood. Efforts were unsuccessful; no larvae were observed exiting from, or during the inspection of, any hives. Possible reasons for these results are discussed. The variability observed in A. tumida reproduction even in controlled laboratory conditions and the difficulty in causing beetle infestations in field experiments involving full colonies suggest that accurately forecasting the A. tumida severity in such colonies will be difficult.