Phalangium opilio is an opportunistic predator frequently found in agricultural habitats. Recently, P. opilio has been shown to feed on many pest species in several crops. Although the potential importance of P. opilio has been recognized, little is known about its activity patterns, its within-plant distribution, or its spatial distribution within large fields. We studied field-scale distribution in commercial soybean fields, and we determined diel activity patterns and within-plant distribution in small, fenced arenas in soybean fields. The fenced arenas allowed us to track known numbers/sizes of P. opilio for each 24h trial. We arbitrarily separated P.opilio into the following categories based on body size: medium immature, large immature, adult male, and adult female. Medium immatures occupy the bottom and middle portions of plants regardless of time of day; they remain still during the day, but they search and feed from 2100 to 0400h. Large immatures rest in the bottom and middle portions of plants during the day, but they walk and search on the ground from 2100 to 0100h. Males remain stationary in the bottom, middle, and top portions of plants during the day, but they walk on the ground from 2100 to 0400h. Females rest in the bottom and middle portions of plants during the day, and they walk and search on the ground from 2100 to 0100h. Results from our large-field studies suggest that in conventionally tilled soybeans, harvestmen densities are higher near field borders than in the interior portions of fields.
Species 1: Opiliones Phalangiidae Phalangium opilio (harvestman)
Keywords: activity patterns, harvestman
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