| dc.description.abstract | Selective predation (i.e., non-random feeding) was studied in a laboratory system
that allowed individual lycosid spiders, Pardosa vancouveri, to feed on prey
populations consisting of one or two kinds of insects. Various combinations of
male and female fruit flies (Drosophila melanogaster), "small" and "large"
beetle larvae (Tenebrio molitor), and nymphal milkweed bugs (Oncopeltus fasciatus)
were used as prey. Female adult and subadult spiders were used as
predators. Generally, fruit flies were selected by the spiders over mealworms or
milkweed bugs, and small mealworms over large ones. No selection occurred
between male and female flies. Very weak or no selection occurred between
small beetle larvae and milkweed bugs. Spiders of both age classes showed
similar selective tendencies. Prior feeding experiences did not alter feeding
selections, but minor changes in the physical complexity of the environment did.
Twelve criteria related to development, survival, growth, and fecundity were
monitored for 12 groups of spiders fed either single or two-prey combinations
of the five kinds of prey. The hierarchy of benefits conferred by the five kinds
of prey was the same as that for selection. Male and female fruit flies equally
benefited the spiders. The fruit flies yielded the most and large beetle larvae the
least number of statistically superior benefits. Small beetle larvae and milkweed
bugs were intermediate and about equal. There was no evidence that a mixed
(i.e., two) prey diet is better than a single prey diet. It is hypothesized that
selective predation by P. vancouveri involves prey sampling, memory of prey
attributes, and selection of prey that possess attributes that are associated with
high fitness. | en |
