Spatial and numerical relationships of arthropod communities associated with key pests of maize

Authors: Lundgren, Jonathan; MCDONALD, TIA - Ohio University; Rand, Tatyana; FAUSTI, SCOTT - South Dakota State University

Submitted to: Journal of Applied Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/22/2015
Publication Date: 6/13/2015
Citation: Lundgren, J.G., Mcdonald, T., Rand, T.A., Fausti, S. 2015. Spatial and numerical relationships of arthropod communities associated with key pests of maize. Journal of Applied Entomology. 139:446-456.

Interpretive Summary: Corn pests are part of a greater community of insects and other arthropods, and their interactions with these other species may influence when and where corn pests occur. Also, tactics to control pests of corn may inadvertently harm these non-target species, and knowing what species occur in corn fields is very important (although poorly understood). We sampled the arthropod communities in 53 farms in Eastern South Dakota, and mapped the distributions of key pests (European corn borer and Corn rootworms) for the first time in this region. We found a number of predators and herbivores that were commonly found in conjunction with corn pests. Arthropod diversity (at least 91 species) was surprisingly high, and predatory species were abundant, with a 167,000 predators per acre in the corn foliage. These other insects may be important indicators of pest problems in corn, or in the cases of predators, these other insects and other arthropods may be important natural enemies of these pests.

Technical Abstract: Pest management largely focuses on managing individual pest species with little concern for the diverse communities that co-occur with key pests and potentially shape their population dynamics. During anthesis, we described the foliar arthropod communities on 53 maize farms throughout the region of Eastern South Dakota. The resulting communities were examined for trends in local associations in the abundances of taxa with key pests in the system (rootworms [Diabrotica spp.], European corn borers [Ostrinia nubilalis], aphids, and Western bean cutworm [Striacosta albicosta]) using regression analyses. Regional spatial clustering in the abundances of key pests with members of the community were explored using Moran’s I test statistic. The distributions of rootworms and European corn borer were mapped. A total of 37,185 arthropods representing at least 91 taxa were collected in South Dakota maize; there was an average of 5.06 predators and 8.29 herbivores found per plant. Key pests were never found at economically threatening levels (with one exception for Diabrotica). Numerous species were consistently numerically associated with each of the key pests across the farms. Occasionally these pests shared species with which they were locally associated with; for example coccinellid egg abundances was predictive of the abundances of all key pest species except rootworm adults. Spatial analysis across the region suggested that species co-occurred with key pests based on local characteristics surrounding the fields, rather than as a result of regional characteristics. Exceptions were documented; namely aphids and western bean cutworms that spatially clustered with a handful of other members of the community. The results of the study point out that the abundances of key pests of maize were interconnected through indirect associations in the abundances of other members of the community. These associations may be useful for manipulating maize agroecosystems to minimize the effects of maize pests.