Comparative Laboratory Toxicity of Neem Pesticides to Honey Bees (Hymenoptera: Apidae), Their Mite ParasitesVarroa jacobsoni(Acari: Varroidae) andAcarapis woodi(Acari: Tarsonemidae), and Brood PathogensPaenibacillus larvaeandAscophaera apis

Abstract

Laboratory bioassays were conducted to evaluate neem oil and neem extract for the management of key honey bee (Apis mellifera L.) pests. Neem pesticides inhibited the growth of Paenibacillus larvae (Ash, Priest & Collins) in vitro but had no effect on the growth of Ascophaera apis (Olive & Spiltoir). Azadirachtin-rich extract (neem-aza) was 10 times more potent than crude neem oil (neem oil) against P. larvae suggesting that azadirachtin is a main antibiotic component in neem. Neem-aza, however, was ineffective at controlling the honey bee mite parasites Varroa jacobsoni (Ouduemans) and Acarapis woodi (Rennie). Honey bees also were deterred from feeding on sucrose syrup containing > 0.01 mg/ml of neem-aza. However, neem oil applied topically to infested bees in the laboratory proved highly effective against both mite species. Approximately 50-90% V. jacobsoni mortality was observed 48 h after treatment with associated bee mortality lower than 10%. Although topically applied neem oil did not result in direct A. woodi mortality, it offered significant protection of bees from infestation by A. woodi. Other vegetable and petroleum-based oils also offered selective control of honey bee mites, suggesting neem oil has both a physical and a toxicological mode of action. Although oils are not as selective as the V. jacobsoni acaricide tau-fluvalinate, they nonetheless hold promise for the simultaneous management of several honey bee pests.

Managed honeybee colony losses of the Eastern honeybee (Apis cerana) in China (2011–2014)

“…Our result further confirms that even though some beekeepers (261 out of 937 in our survey, 28%) take measures to treat for varroa mite in A. cerana colonies, it may not be necessary. In addition, treatment of varroa mite increases the cost of management and can lead to side effect on the bees (Higes et al 1999;Mattila et al 2000;Melathopoulos et al 2000;Rinderer et al 1999) and chemical residuals in honeybee products (Wallner 1999). Therefore, beekeepers should be cautious when deciding whether to treat for varroa mite.…”

Assessing delayed and acute toxicity of five formulated fungicides to Osmia lignaria Say and Apis mellifera

“…Neem oil contains many potentially bioactive constituents that vary among crude extracts (Schmutterer, 1995). Several neem-based insecticides were investigated for their anti-feeding effects on adult worker honey bees and for toxicity to A. mellifera workers and larvae (Naumann et al, 1994;Naumann and Isman, 1996;Melathopoulos et al, 2000;Peng et al, 2000), and applications were considered relatively safe to honey bee workers and larvae. Therefore, if direct exposure of bees is avoided, neem oil would be compatible with bees during the pollinating season.…”

Lethal and sublethal effects of azadirachtin on the bumblebee Bombus terrestris (Hymenoptera: Apidae)

“…Until now, there is no study related to the effects of azadirachtin on bumblebees, and the few existing studies were exclusively carried out with Apis mellifera 17,18 . Therefore, in this study we hypothetised that azadirachtin could lead to lethal and sublethal effects on morphology and reproduction of B. terrestris.…”