Phalangium opilio is an abundant predator in an array of habitats. During the past two decades, P. opilio has been cited as a major component of the generalist predator complex in several agricultural systems. In these systems, P. opilio has been noted to feed on several soft-bodied pest species (e.g., Leptinotarsa decemlineata larvae, various aphid species and lepidopteran eggs). Although the potential importance of P. opilio has been recognized, little is known about this harvestman’s reproductive biology. We studied P. opilio reproduction (number of clutches, clutch size, interval between clutches and adult female longevity) and the influence of diet on its reproductive capabilities. The four diet treatments were: (1) cornmeal, bacon and Helicoverpa zea eggs; (2) Aphis glycines only; (3) H. zea eggs only; (4) A. glycines and H. zea eggs. Treatments began at the beginning of the penultimate instar and continued until mortality. Female P. opilio live an average of 85 d and lay a mean number of 1.6 clutches with a mean clutch size of 92 eggs. The A. glycines-only treatment was significantly different from the other three diet treatments. Females in this aphid treatment experienced decreased longevity, decreased clutch size and increased time from adult emergence to oviposition.
Species 1: Opiliones Phalangiidae Phalangium opilio (harvestman, daddy long-legs)
Species 2: Lepidoptera Noctuidae Helicoverpa zea (corn earworm)
Species 3: Homoptera Aphididae Aphis glycines (soybean aphid)
Keywords: fecundity
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