Arthropod Abundance and Community Structure in Adjacent Cotton and Alfalfa on the Texas High Plains

Abstract

A study was designed to examine the community composition of canopydwelling arthropods in adjacent fields of cotton, Gossypium hirsutum L., and alfalfa, Medicago sativum L., at Texas A&M University AgriLife Research and Extension Center farm near Lubbock, TX, during the cotton-growing seasons of 2008 and 2009. Samples were collected from 61 row-meter sections of cotton (1.02-m row spacing) and 61 row-meter sections of alfalfa (0.51-m spacing) via a “Keep It Simple Sampler” (KISS). Six samples were collected on each of 11 weekly sampling dates during the cotton-growing seasons of both years. We found that specimens in the canopy-dwelling arthropod community in cotton and alfalfa were from the orders Araneae, Coleoptera, Diptera, Hemiptera, Hymenoptera, Lepidoptera, Neuroptera, and Orthoptera, and in the orders, 41 families were identified. Members of Araneae, Coleoptera, and Hemiptera were most abundant in both crops. Overall, a greater number of arthropod taxa was found in alfalfa, but some arthropod taxa were unique to each crop. Analyses revealed a difference in temporal abundance of captured arthropods at the order (p ≤ 0.018) and family levels (p ≤ 0.021) during cotton squaring, flowering, and boll-development stages, with significantly greater abundance of arthropods at the order level in alfalfa compared to cotton in both years, except during the cotton-flowering period in 2008. Implications of arthropod community differences between alfalfa and cotton were discussed with respect to using alfalfa as a potential source of predators for adjacent cotton.