Journal of Insect Science (2008) 8 (49), p. 11 (Fournier et al.)

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A. Fournier, P.C. Ellsworth and V.M. Barkley (2008)
Economic impact of Lygus in Arizona cotton: A comparative approach
Journal of Insect Science 8 (49), 11-11
in P.B. Goodell and P.C. Ellsworth, organizers: Second International Lygus Symposium, Pacific Grove, California, April 15-19 2007
Abstract: In the Western U.S., Lygus spp., especially L. hesperus, (Hemiptera: Miridae) can cause major losses to cotton, vegetables, seed crops, and a variety of other crops. However, the economic impact of this pest remains largely undocumented in most crops. Two major data sources quantify current management practices and the economic impact of Lygus in low-desert upland cotton production in Arizona. A statewide Pesticide Use Reporting (PUR) database, compiled from information reported by applicators to the Arizona Department of Agriculture, documents a high proportion of Lygus applications in cotton, though not all types of applications require reporting. In addition, an annual "Cotton Insect Losses" (CIL) survey of cotton Pest Control Advisors (PCAs) helped to provide a more complete picture of statewide Lygus management practices. Five years of data (2001-2005) were analyzed. Lygus is the most important pest in Arizona cotton most years, based on application*acres of all foliar insecticides. Whitefly [Bemisia tabaci (Genn.), biotype B] is the most important Lygus co-target, when applications are aimed at controlling more than one pest. The most commonly used foliar materials against Lygus in Arizona cotton are acephate, endosulfan and oxamyl, which are typically used at about 90% of maximum label rates. About 80% of Lygus applications occur between mid-July and late-August. The two sources of data (CIL and PUR) provide independent estimates of the average number of Lygus sprays per acre. Except for 2004, the CIL data estimates somewhat higher insecticide use against Lygus than PUR data. Several reasons for this discrepancy were identified, including less than 100% pesticide use reporting in the PUR database; differences in the insecticides included in the estimates; and differences between how the two datasets apportion a single spray event among multiple pest targets. The intensity of Lygus insecticide use varies by county. Pinal County, which has the most cotton acres, shows the highest sprays per acre of the top three active ingredients to control Lygus. A section-level analysis of 2005 PUR data indicates a relationship between the intensity of cotton production and spray intensity for Lygus control. Growers in Township - Ranges with a low proportion of cotton sections (10-15%) tend to make more sprays on average to control Lygus. However, Township - Ranges with the lowest and highest proportions of cotton sections (<10% and >90%) tend to show trends towards fewer sprays for Lygus control. These data suggest the possibility that landscape factors can influence Lygus populations at the local level, although more research in this area is needed. Lygus is perhaps the most significant economic pest of Arizona cotton. Cotton Insect Losses survey data indicate that a high proportion of cotton insect chemical control efforts are directed toward Lygus control. About 40% of foliar insecticide sprays target Lygus, accounting for about one third of the foliar insecticide budget for growers most years. Despite these control efforts and associated costs, CIL survey respondents consistently rank Lygus as the most damaging insect pest of cotton, accounting for more than 50% of insect-related yield loss most years. These data provide important baseline information that will allow us to measure changes in Lygus management practices and economic impact over time. Future Lygus management practices might be influenced by (1) the introduction of new selective chemistry for Lygus control; (2) the introduction of transgenic control options for Lygus; or (3) landscape-level changes that could have area-wide impact on Lygus management in cotton and other crops. These data underscore the need for continued research to develop effective, selective tools for improved Lygus management in cotton, and to integrate these into effective Integrated Pest Management (IPM) programs. There is a need to similarly document the economics of Lygus management in other crops including vegetables, seed crops, and alfalfa, and the impact of landscape-level factors on Lygus management in a variety of crops.
Database assignments for author(s): Peter C. Ellsworth

Research topic(s) for pests/diseases/weeds:
control - general

Pest and/or beneficial records:

Beneficial Pest/Disease/Weed Crop/Product Country Quarant.

Lygus hesperus Cotton (Gossypium) U.S.A. (SW)