Effects of a Foliar Neem Formulation on Colonization and Mortality of Whiteflies (Hemiptera: Aleyrodidae) on Collard Plants

A study was conducted to determine the effects of foliar sprays of a selected neem (Azadirachta indica A. Juss) product (GOS Neem 7-Way) on colonization and development by the Middle-East Asia Minor-1 (= B-biotype sweetpotato whitefly) Bemisia tabaci (Gennadius) on collard (Brassica oleracea variety acephala de Condolle) plants. GOS Neem 7-Way is marketed for use as an insecticide in organic and conventional crop production. Caged choice, caged no-choice, and Y-tube olfactometer assays were conducted on oviposition, survival and adult behavioral response to plant treatment with 1.25% azadiractin. In the caged choice experiment, colonization by the whiteflies was reduced and fewer eggs were deposited on neem-treated plants as compared with control plants (only treated with an adjuvant). Similarly, decreased numbers of adult whiteflies and reduced whitefly development were observed in no-choice assays for the neem-treatment, as compared with the untreated control. Both horizontal and vertical-orientated Y-tube olfactometer assays provided complementarily assessments that the neem had a repellency effect on the adult whiteflies. However, the repellency effect primarily dissipated within one day post treatment. Overall, the greatest benefit of the neem treatment appears to have been on whitefly mortality. The findings may be useful in providing a more ecologically sound way to manage populations of the B. tabaci whitefly in organic vegetable production.

Comparison of Three Single-Nozzle Operator-Carried Spray Applicators for Whitefly (<i>Bemisia tabaci</i>) Management on Squash

Whiteflies cause problems in vegetable production on a global scale. The primary worldwide whitefly pest is Bemisia tabaci (Gennadius). Insecticides are commonly used to mitigate the whitefly problem in vegetable crops. In limited-resource crop production, operator-carried spray applicators are commonly used for pesticide treatments. Three single-nozzle operator-carried spray applicators were assessed for their efficacies for whitefly (B. tabaci) control on summer squash (Cucurbita pepo L.) in Egypt. Each knapsack spray equipment was evaluated with five biorational and conventional insecticides. Counts of whitefly nymphs (first, second, third and fourth instars) on leaf samples were taken on 3, 9, 15 and 21 days after treatments with the insecticides. Nymphal mortality varied about 10% among the three spray equipment treatments. The Economy Micro Ulva sprayer resulted in significantly more nymphal mortality as compared with the Arimitsu sprayer and the CZP-3 sprayer, respectively. All insecticides greatly suppressed the whitefly populations;mean mortality ranged from 73% to 95% for all nymphs combined by day for a given treatment. These results provide pest management practitioners with performance assessment of the three operator-carried pesticide applicators for whitefly management with selected foliar insecticides.

Inundative field releases and evaluation of three predators for Bemisia tabaci （Hemiptera： Aleyrodidae） management in three vegetable crops

The sweetpotato whitefly, Bemisia tabaci （Gennadius） （Hemiptera： Aleyrodidae）, is a global pest on numerous crops, including vegetables. Weekly inundative releases of a coccinellid predator （Coccinella undecimpunctata L. [Coleoptera： Coccinellidae]）, a common green lacewing predator （Chrysoperla carnea Stephen [Neuroptera： Chrysopidae]）, and a mirid predator （Macrolophus caliginosus [Wagner] [Hemiptera： Miridae]） were independently made in three vegetable crops （cabbage [Brassica oleracea var. capitata L.], cucumber [Cucumis sativus L.], and squash [Cucurbita pepo L.]） for the management of the sweetpotato whitefly. Approximately 1 million to 2.5 million larvae or nymphs of each predator were released in the vegetable crops during 20 weeks. Whitefly populations were reduced by ≈ 25%-45% during most of the season in each crop where each predator was released. The effect of each predator was similar on whitefly population reduction. Late in the season （October） when whitefly populations were low, generally no benefit was obtained from releasing the predators. Numbers of predators recovered during sampling in all crops were greatest for C. carnea, but this corresponded with the fact that more individuals of this predator were released than any other predator in the experiment. These results help define the utility of these natural enemies for managing B. tabaci in vegetable crops.