PS 60-162 - Male wool carder bees attack a variety of floral visitors

Thursday, August 10, 2017
Exhibit Hall, Oregon Convention Center
Gary C. Chang, Biology, Gonzaga University, Spokane, WA

Anthidium manicatum is a species of wool carder bee that is native to Europe and parts of Africa and Asia. It was first collected in the United States in the 1960s. It is uncertain how long it has been present in Spokane, Washington, where the current study was conducted. Male A. manicatum patrol flowers and attack conspecific males and other floral visitors. I collected observational data to evaluate the time budget and interactions of male A. manicatum in cultivated flower beds during 19-21 July 2016. I observed focal male A. manicatum for 30-minute periods in the morning and afternoon on each day and recorded their activities (patrolling, foraging, copulating, and resting). I recorded duels between male A. manicatum, mating encounters, and interspecific encounters. I classified an interspecific interaction as an attack when I observed physical contact, or intimidation when A. manicatum repelled an insect without apparent physical contact.


Overall, 75% of the time budget of male A. manicatum was spent patrolling. The next most commonly observed behavior was foraging (7%), followed by resting (5%) and copulating (4%). Within observation periods, the number of mating encounters was positively correlated with the proportion of time spent copulating (correlation coefficient = 0.88) and negatively correlated with the proportion of time spent patrolling (correlation coefficient = -0.49). The proportion of time spent patrolling was significantly greater during afternoon observations (79%) than morning observations (70%; paired t-test: t=-7.4572, df=2, p<0.05). A total of 25 mating encounters were observed during the entirety of observations, along with 26 duels. Other observed interactions consisted of 17 interspecific attacks and 63 intimidations. Honey bees, bumble bees, and paper wasps were attacked by A. manicatum. In contrast to results from other sites, none of the observed attacks appeared to cause lasting damage. Additional work is planned for summer 2017 to test the hypothesis that the attacks by A. manicatum reduce the abundances of other insects in patrolled areas.