DIETS, FEEDING SPECIALIZATION, AND PREDATORY ROLE OF 2 LYNX SPIDERS, OXYOPES-SALTICUS AND PEUCETIA-VIRIDANS (ARANEAE, OXYOPIDAE), IN A TEXAS COTTON AGROECOSYSTEM

The predation ecology of the striped lynx spider, Oxyopes salticus Hentz, and green lynx spider, Peucetia viridans (Hentz), was studied during 108 h of visual observation in an insecticide-free cotton field in central Texas. Evidence obtained during this study indicates that lynx spiders were the dominant arthropod predators (among 134 cases of arthropod predation observed, 94 were attributable to lynx spiders). P. viridans is a powerful species (10.08 +/- 0.52 mm [mean +/- SEM] body length) compared with the significantly smaller O. salticus (4.24 +/- 0.16 mm). The O. salticus individuals fed on small-sized prey (2.41 +/- 0.17 mm average prey length). In contrast, the P. viridans individuals fed over a broader range of prey size classes and captured a higher proportion of the larger prey organisms (7.04 +/- 0.73 mm average prey length). However, the smallest P. viridans (less-than-or-equal-to 8 mm spider length) and the largest O. salticus (greater-than-or-equal-to 4.5 mm spider length) selected prey of similar average length (almost-equal-to 3 mm). The lynx spiders are polyphagous insectivores that feed on a variety of prey species predominantly in the insect orders Heteroptera, Hymenoptera, and Diptera. They also frequently eat other spiders. The most frequently captured prey of O. salticus were small Heteroptera (predominantly cotton fleahopper, Pseudatomoscelis seriatus [Reuter]), whereas P. viridans most frequently seized large stinging Hymenoptera (e.g., honey bee, Apis mellifera L.). The degree of the feeding specialization of the two spider species was mathematically assessed (niche breadth coefficients) and statistically compared; computed coefficients indicate that P. viridans is a significantly more polyphagous predator than the smaller-sized O. salticus. O. salticus, therefore, shows a better fit to the "model predator" of classical biological control because of its relative specialization.