Arizona Russian Wheat Aphid Survey and Beneficial Release Report, 1990

During 1990 the emphasis on surveying was placed in the southeastern corner of the state, where damage was found to be most severe in previous years. Estimates of the incidence of and damage caused by the Russian Wheat Aphid (RWA) were made for the entire state. These estimates indicate that small grain producers in the state lost $212,000 due to this pest in 1990. Introduction Russian wheat aphid (RWA) have been a continuing problem in parts of Arizona since their presence was confirmed in 1987. This survey was made to determine its presence throughout the state for our own records as well as to join together with other states to provide an estimate of the RWA damage caused throughout the country. This report was presented at the Fourth Annual Russian Wheat Aphid Conference in Bozeman, Montana. Materials and Methods Information in this report on the presence of RWA was summarized from the data found in Russian Wheat Aphid Survey in Southeastern Arizona, 1990, found elsewhere in this same publication and by polling Extension Agricultural Agents and IPM specialists throughout the state. Information on the beneficial insects released were summarized from our release records. The release project is a cooperative project between USDA -APHIS -PPQ, the Arizona Department of Agriculture and the University of Arizona Cooperative Extension. Exotic species of parasitic wasps and predatory lady beetles from Europe, Asia and Canada were shipped to Safford from USDA locations in Michigan and Texas. These parasitic and predaceous insects, which were shipped overnight in cooled containers, were released in the chosen sites around dusk of the day they were received. It was important to release them at dusk to keep them from flying from or being blown from the targeted area. In the case of the lady beetle egg release in northern Cochise county, timing of release was not so critical. These eggs were placed during the day that the shipment was received or the next day. Discussion . The largest percent infestations occurred in the counties in the high desert ( >3000 feet above sea level). In addition to these three counties, RWA were also found in Maricopa, Pima and Pinal counties, but at much lower infestation rates. A summary of losses and costs caused by the RWA are found in Table 1. This gives an estimated loss to Arizona grain producers of over $212,000, including crop loss and cost of treatment. In the central counties of Arizona, infestations were about average to light. Graham county, however, had its worst infestations since RWA came into the county in 1987. RWA are in the Imperial Valley of California and their presence has been expected in Yuma and LaPaz counties on the west edge of the state, but up to this point none have been found.