Submitted to: Journal of Entomological Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 8, 1997
Publication Date: N/A
Interpretive Summary: The future of US agriculture is in areawide integrated pest management (IPM), which is IPM over several contiguous agricultural areas. Critical to successful areawide IPM is the development of accurate, yet cost effective sampling methods, together with an understanding of the effects of farming practices on insect movement. We tested the applicability of areawide IPM against the silverleaf whitefly in a mixed crop of cotton, cantaloupes, and kenaf (a forage legume). High numbers of parasites were found in kenaf. Insect counts derived from sticky traps did not appear to correlate with direct counts on leaves. However, we could predict the numbers found on entire leaves using leaf subsamples. In cantaloupes, harvesting apparently caused the whiteflies to move to nearby cotton. The causes of movement out of cotton were less clear, although leaf aging was probably a main factor. Whiteflies may be difficult to manage using areawide IPM because they migrate easily as a result of cropping practices, and they attack many plant crops.
Populations of the silverleaf whitefly (SLWF), Bemisia argentifolii Bellows & Perring, and its endemic parasitoids were monitored in a heterogenous crop, consisting of cotton, cantaloupe and kenaf. We compared estimates of populations using different sampling methods, and determined the effects of agronomic practices on the whitefly and parasitoid populations. Insect counts derived from sticky traps did not appear to correlate with direct counts on leaves. However, counts derived from disk subsamples were good predictors of whole leaf counts. SLWF counts were lower in the cantaloupes compared to cotton. Whiteflies apparently migrated during cantaloupe harvesting to the nearby cotton fields. Determinants of emigration from cotton were less clear, although one likely contributing factor was leaf senescence. Parasitoid populations were high in the kenaf fields, a possible reservoir of natural enemies with a larger cropping system. Because SLWF is a despersive and polyphagous pest, areawide management of the whitefly must consider the consequences of farming practices and cropping patterns in heterogenous fields, especially when the fields are under different ownerships.