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Abstract:
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Eastern cicada killers,
Sphecius speciosus
Drury, are large, ground-nesting, mass-provisioning
wasps that use cicadas to feed their offspring. Previous studies have reported that female
S. speciosus
provide each male offspring with 1 or rarely 2 cicadas, and each female
offspring with 2 or rarely 3 cicadas, regardless of cicada size. We collected samples of male
and female cicada killers and samples of their cicada prey from 12 locations in 10 different
states of the USA. We measured right forewing length of the wasps and dry body mass of the
cicadas as indicators of size; ANOVA revealed significant differences in mean masses among
local populations of cicadas. We predicted that wasp size would also vary among locations,
and would be positively correlated with mean size of local cicada prey. ANOVA did reveal significant
differences in mean wing length in both male and female wasps among study sites.
Regression analysis, with local mean cicada mass as the independent variable and local
mean wasp wing length as the dependent variable, suggests that the size of available cicada
prey is a good predictor of size for both male and female
S. speciosus. |