Honeybee Foraging Preferences, Effects of Sugars and Fruit Fly Toxic Bait Components

Authors: Mangan, Robert; Tarshis Moreno, Aleena

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/3/2009
Publication Date: 8/3/2009
Citation: Mangan, R.L., Tarshis Moreno, A.M. 2009. Honeybee foraging preferences, effects of sugars and fruit fly toxic bait components. Journal of Economic Entomology. 102(4):1472-1481.

Interpretive Summary: Following public complaints about perceived dangers of malathion based toxic baits for fruit fly management or eradication in area-wide programs, we developed a more effective bait that could be used with feeding stimulants to poison fruit flies. This bait allowed application of insecticides at thousands of times lower concentration and use of more expensive insecticides having much lower vertebrate toxicity. The commercial product we developed, GF-120, has been shown to have much lower toxicity to vertebrates than malathion, and to be used at 80 parts per million concentration, compared to 100,000 to 200,000 parts per million (10-20%) for malathion based baits. The spinosad insecticide is a microbial product which has allowed the bait to be registered as an organically approved insecticide. Tests, performed in tropical habitats during the registration procedure, showed that the bait did not increase mortality or reduce honey production in bee hives located in sprayed areas, compared to non-sprayed controls. However, some publications reported high mortality when honeybees were caged under laboratory conditions with GF-120 presented as food for the bees. Our tests reported, in this publication, used a procedure of training the bees to forage at a site 100 meters from the hive, then presenting the bees with a choice of the GF-120 bait or bait components and honey-water for feeding. Positions of the bait and honey were switched at 15 minute intervals. Counts showed that bees were repelled by the complete bait and by the hydrolyzed protein and ammonia components that serve as attractants to the fruit flies. Other than occasional “crash landings” into the bait, from which the bees could not fly from, no bees were observed to land and feed on the bait. In tests carried out as no-choice tests in which bees were trained to go to the feeding site, then offered only bait components or complete bait, bees stopped landing on the sites as soon as the honey-water was removed and replaced by the bait or attractant components. These results showed that, not only are bees not feeding on the bait, they are repelled by the bait odor and are unlikely to accidentally contact bait drops and contaminate hives.

Technical Abstract: Field tests were carried out to evaluate the repellence of the fruit fly toxic bait, GF-120, for domestic honeybees. This bait is an organically registered attractive bait for tephritid fruit flies and is composed of hydrolyzed protein (Solulys), invertose sugar, vegetable oils, adjuvants, and other additives as humectants and attractants. The toxic component is spinosad at ca. 80 ppm AI. All tests were carried out with non-Africanized honeybees belonging to the Honey Bee Research Unit at the USDA-ARS research center at Weslaco, Texas. Tests were run during the periods of maximum hunger for these bees during February and March 2005 and 2007. In all tests, bees were first trained to forage from plates of sugar water or 30% dilute honey-water following methods from established literature. In 2005, bees were then offered choices between the honey-water and various bait components, including complete toxic bait. In 2007, these same types of tests were performed, except that bees were first attracted to the site with honey-water then offered the bait components or complete bait as non-choice tests. The first tests used all the components of GF-120, except the spinosad as the test bait. Tests were carried out for 1 hour with bait and honey-water positions; water positions were switched every 15 minutes and counts made every 5 minutes. After we were convinced that bees would not collect or be contaminated by the bait, we tested the complete GF-120 bait. Behavior of the bees indicated that during initial attraction and after switching the baits, the bait components and the complete bait were repellent to honeybees, but the honey water remained attractive and was collected. Invertose sugar was shown to be less attracted to fewer feeding bees; addition of solulys eliminated almost all bee activity and addition of ammonium acetate completely eliminated feeding in both choice and no-choice tests. These results coincide with previous tests showing that bees do not feed on GF-120, but also show that honeybees are repelled by the attractant components of the bait in field tests.