Issue link: https://www.e-digitaleditions.com/i/1099801
9 4 Kulhanek, Kelly et al. 2017. A national survey of managed honey bee 2015-2016 annual colony losses in the USA. Journal of Apicultural Research. 56 (4): 328-340. https://www.tandfonline.com/doi/abs/10.1080/00218839.2017.1344496 5 Mussen, Eric. 2013. Problems with almond bloom sprays. UC Apiaries newsletter, Jan./Feb. 2013. 6 Johnson, Reed. 2017. Effects of Insecticide-Fungicide-Adjuvant Combinations Commonly applied during bloom on Honey Bee Development and Survival. Almond Board of California 2017 Research Update, p. 47. PROTECTING HONEY BEES AT BLOOM Due to a combination of factors, including Varroa mite, loss of natural forage, disease and the effects of some pesticides, beekeepers are losing a large number of colonies. 4 Researchers continue to study the causes of these losses and how to prevent them; this is an ongoing effort. Honey bees are vulnerable to many of the pesticides used to control insects, disease and weeds. As such, pesticides that are used within the hive for mites and disease control, as well as those applied on crops, are currently under investigation. Their methods of application are also under investigation. California almond growers must maintain a delicate balance between protecting their crop from disease, insects and weeds, while at the same time protecting honey bees from potentially harmful pest control materials. HONEY BEES AND INSECTICIDES Insecticides — a term that includes insect growth regulators, also known as IGRs — should not be applied during bloom. The only exception is Bacillus thuringiensis (Bt), which can be applied safely because it is documented to be safe for both adult and immature bees. Some bee losses in almonds also have been associated with tank-mixing insecticides and bloom-time fungicides. While these losses could have other causes, tank-mixing warrants a scientific basis for concern that is based on a combination of field experience and controlled studies. 5,6 Currently, most bee label warnings are only based on adult acute toxicity studies; however, recent information indicates some pesticides, insecticides included, may be harmful to developing eggs, larvae or pupae (collectively referred to as "bee brood") in the hive. Because the length of a brood's lifecycle is about 21 days, problems like deformed wingless bees that fail to emerge from the hive may not appear until after almond bloom. Specifically, deformed wingless bees are pulled from their comb cells by other bees and then are commonly found in front of the Insecticides can have an impact on immature bees. Here, deformed wingless bees that have failed to emerge have been pulled from their comb cells by other bees, leaving those comb cells empty. hive entrance, leaving those comb cells empty. The Environmental Protection Agency (EPA) now requires data for possible pesticide effects on bee brood. Insecticide residues, specifically, have been detected in the pollen that foragers bring back to the hive, which is fed to the bee brood. Furthermore, controlled studies 6 demonstrate that some insecticides are known to interact with some fungicides, such that when they are tank-mixed they can have greater cumulative toxicity to bees than either chemical used alone. This synergy is being documented in ongoing studies, 6 so until more is known, avoid tank-mixing an insecticide — except for Bt — with a fungicide during almond pollination. It is important to note that tank-mixing of a number of these insecticides and fungicides is not specifically prohibited by the label. The EPA and the California Department of Pesticide Regulation (DPR) are looking to include warnings on product labels to outline which specific tank-mixing combinations should not be made.