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Whiteflies are a key factor affecting tomato yields in Puerto Rico by causing direct mechanical damage and as vector of geminivirus. Searching for alternate control means of whitefly, field trials were established at Gargiulo's Farm, Santa Isabel and in the Fortuna Agricultural Experiment Station at Juana Diaz, Puerto Rico. Whitefly natural enemies were identified. The use of refuge crops for whitefly natural enemies was also evaluated.
The whitefly affecting tomato yields in the south of Puerto Rico is Bemisia argentifolii Bellows & Perring (Homoptera: Aleyrodidae). Twenty-three (23) species of spiders in nine (9) families were identified as natural enemies of the whitefly, being Anelosimus sp. the most abundant. Among the coccinelid predators eight (8) species were identified; Delphastus sp. was the most abundant. The aphelinids Encarsia sp. and Eretmocerus spp. were the most common parasitoids.
Among the refuge crops, Crotalaria juncea, hosted the largest parasitoid population and an intermediate whitefly density. Broccoli hosted the largest whitefly density as well as the largest number of natural enemies. The use of broccoli as refuge to whitefly natural enemies has potential, but additional research is needed.
The use of the insecticides endosulfan + lamdacialotrina + cypermetrina did not reduce whitefly populations as compared to the unsprayed treatment. The use of imidacloprid, as drench, effectively controlled the whitefly and improved yields as compared to the control.
The lowest whitefly densities were recorded for the Asteracea, Wedelia trilobata, being a plant with potential use as refuge. The density of whitefly in W. trilobata was similar to tomato treated with imidacloprid. The refuge crops, Hibiscus esculenta and Oscimum basilicum attracts the whitefly. However, its use on commercial tomato plantings needs to be monitored, as the whitefly might migrate to the crop. (Abstract shortened by UMI.)