Behavioural responses of the small hive beetle to volatile components of fermenting honeybee hive products

The small hive beetle, Aethina tumida Murray (Coleoptera: Nitidulidae), is a significant pest of managed honeybees in the USA and eastern Australia. The beetle damages hives by feeding on hive products and leaving behind fermented wastes. The beetle is consistently associated with the yeast Kodamaea ohmeri (Etchells & Bell) Yamada et al. (Saccharomycetales: Metschnikowiaceae), and this yeast is the presumed agent of the fermentation. Previous work has noted that the small hive beetle is attracted to volatiles from hive products and those of the yeast K. ohmeri. In this study, we investigated how the volatile compounds from the fermenting hive products change depending upon the source of the hive material and also how these volatiles change through time. We used gas chromatography–mass spectrometry and choice‐test behavioural assays to investigate these changes using products sampled from apiaries across the established range of the beetle in eastern Australia. The starting hive products significantly affected the volatile composition of fermenting hive products, and this composition varied throughout time. We found 61.7% dissimilarity between attractive and non‐attractive fermenting hive products, and identified individual compounds that characterise each of these groups. Eleven of these individual compounds were then assessed for attractiveness, as well as testing a synthetic blend in the laboratory. In the laboratory bioassay, 82.1 ± 0.02% of beetles were trapped in blend traps. These results have strong implications for the development of an out‐of‐hive attractant trap to assist in the management of this invasive pest.     

一株从临床分离的奥默儿玉氏酵母的生物学特征及其致病毒力相关特性

奥默儿玉氏酵母Kodamaea ohmeri已经成为一种重要的新兴人类酵母病原体。本文利用形态学和ITS序列分析鉴定分离自患者腹水的临床菌株3873为K. ohmeri。5-氟胞嘧啶、两性霉素B、氟康唑、伊曲康唑和伏立康对菌株3873的MIC值分别为≤4、≤0.5、≤4、≤0.125和≤0.6 mg/L。菌株3873在血清诱导下发育出假菌丝,无法形成真菌丝,且在微需氧条件下侵入能力强;最适生长温度和pH分别为37℃和7.0,在此条件下细胞表面疏水性也最高;采用试管法和微平板法静置培养48h形成大量生物膜;在体外培养条件下,对刚果红、羟基脲和H₂O₂具有一定的耐受能力,对NaCl试剂较为敏感。本研究有助于更好地了解K.ohmeri的基本生物学特征和与其毒力相关的特性。     

Increased attractiveness of honeybee hive product volatiles to adult small hive beetle,Aethina tumida,resulting from small hive beetle larval infestation

The small hive beetle, Aethina tumida Murray (Coleoptera: Nitidulidae), is a recent but significant pest of honeybee [Apis mellifera L. (Hymenoptera: Apidae)] hives in various regions throughout the world, including Eastern Australia. The larval stage of this beetle damages hives when they feed on brood, pollen, and honeycomb, leaving behind fermented wastes. In cases of extreme damage, hives collapse and are turned to an odorous mass of larvae in fermenting hive products. The yeast Kodamaea ohmeri (Etchells & Bell) Yamada et al. (Ascomycota) has been consistently isolated from the fermenting material as well as each life stage of this beetle. Various studies have noted that the small hive beetle is attracted to volatiles from hive products and those of the yeast K. ohmeri, although earlier studies have not used naturally occurring hive products as their source of fermentation. This study investigated changes through time in the attractiveness of natural honeybee hive products to the small hive beetle as the hive products were altered by the action of beetle larvae and fermentation by K. ohmeri. We used gas chromatography‐mass spectrometry and choice‐test behavioural assays to investigate these changes using products sampled from three apiaries. Attractiveness of the fermenting hive products (‘slime’) increased as fermentation progressed, and volatile profiles became more complex. Fermenting hive products remained extremely attractive for more than 30 days, significantly longer than previous reports. These results have strong implications for the development of an external attractant trap to assist in the management of this invasive pest.