Estimating reproductive success of Aethina tumida (Coleoptera: Nitidulidae) in honey bee colonies by trapping emigrating larvae

Behavioral response of the small hive beetle, Aethina tumida (Coleoptera: Nitidulidae) to volatiles of Apicure®, a plant-based extract

Background: The small hive beetle (SHB), Aethina tumida is an invasive pest of the honey bee. Although no previous methods have led to its successful management, yeast inoculated pollen baited-traps have showed promise as quick monitoring tools. In this study, we evaluated the role of olfaction in SHB response to Apicure®, an essential oil-based biopesticide that has shown potential for the management of honey bee pests and diseases. Methods: Volatiles from Apicure® were collected using super Q adsorbent traps. Subsequent analysis was done using Gas chromatography- mass spectrophotometry (GC-MS) to ascertain the components of Apicure®. The selectivity and sensitivity of antennal receptors of A. tumida adults to the volatile compounds were determined using behavioral assays and Gas Chromatography-Electroantennodetection (GC-EAD). Results: GC-MS analysis showed that Apicure® consists of 40 compounds. GC-EAD analysis isolated 11 compounds that elicited antennal response with the SHB. Of these, linalool, camphor, geraniol and α-terpineol were confirmed to be strongly repellant, while limonene was attractive to SHB in dual-choice olfactometer assays. Conclusion: Our results demonstrate that the major components in Apicure® are mainly repellants thus prospective in disrupting the host recognition by the SHB. The product therefore can be up-scaled for the management of SHB.

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 32°C, but did at 28°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 28°C produced more larval mass than at 32°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.