Devanie Harper, 2017

Los Medanos College

Smile, You’re on Camera: Factors impacting resource return in Bombus impatiens

The purpose of this study was to determine if conopid fly (Diptera, Conopidae) parasitism has a significant impact on foraging productivity in the bumble bee species Bombus impatiens. This study analyzed factors that influence foraging productivity, including parasitism by conopid flies, time of day, and foraging experience. However, in the sample of sixteen bumble bees collected, only three were parasitized by conopid flies. This led us to focus primarily on time of day and foraging experience. Foraging efficiency was defined as resources returned per hour per foraging trip, and was analyzed for changes at different times of day, after overnight trips, and after gaining foraging experience. In order to track foraging behavior within a commercial colony, 190 individuals were tagged with radio frequency identification (RFID) chips, along with a unique colored and numbered tag to easily distinguish each individual visually. RFID chips were used to determine the duration of each foraging trip and the times of departure and return for every marked individual. Weights of individuals were recorded as they exited and entered the colony for every foraging trip using a scale and video cameras, and the floral resource load an individual returned with was calculated as the difference in returning and departing weight. In total, my sixteen individuals made 358 foraging trips, and 241 were used in the data analysis. Individuals were removed after 5 or more days of foraging, and then dissected to determine if they were infected by a conopid parasite. We found foraging efficiency increases with experience, and efficiency is higher in the morning than evening. Also, more resources are returned per trip with experience, and individuals reach maximum returns per trip around day 4 of foraging.


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