What modeling populations of the small hive beetle, Aethina tumida, tells us

Aethina tumida is an important invasive bee pest that can cause severe problems in some locations in the United States, and in now found throughout the southern and southeastern U.S. Adult beetles enter honey bee colonies, where they lay eggs in crevices in the hive, and both larvae and adults feed on pollen, brood, and honey. Large A. tumida populations can overwhelm bee colony defenses and cause hive collapse. Aethina tumida usually spends its egg, larval and adult stages in the controlled environment of the bee hive, with abundant food and few or no predators or parasitoids, and a single adult female can lay 2000 or more eggs in her lifetime, so there is potential for the beetles to become a large problem indeed.  However, the beetles must reckon with the need to pupate outside the hive, and with the honey bees themselves. We constructed a temperature-driven population simulation model of A. tumida to evaluate, given what we know about beetle development, survivorship and oviposition across different temperatures, and beetle intra-specific competition effects, how well beetles could do in the absence of bees. To get bees into the equation, we then tried to provoke the bee colony collapse in field experiments in southern Texas, where A. tumida are common in bee hives, by either introducing large numbers of beetles, removing capped brood frame (to reduce the nurse bee population) or both. In spite of these efforts , we were unable to cause major A. tumida infestations in any hives in any field experiments, suggesting that: 1) local climate may have a greater impact than we thought; and 2) cleaning by nurse bees may have less impact than we thought.