Different pairs of plants planted in a single pot were tested in the greenhouse for oviposition preference by the silverleaf whitefly, Bemisia argentifolii Bellows & Perring (Hemiptera: Aleyrodidae). Treatments were: 2 giant red mustard plants (Brassica juncea (L.) Czern.), 2 collards (Brassica oleracea L. var. acephala), and 1 plant of each species in individual pots. Treatments were exposed to whitefly adults and numbers of eggs laid were counted 6 d later. Numbers of whitefly eggs were significantly lower on the mustard-mustard treatment. Average egg counts were lower on collard plants in the treatment where both host plants were presented simultaneously than in treatments where collards were presented alone. These results suggest the possibility of repellent volatiles in the giant red mustard. To test for repellent effects in the field, an experimental plot was planted with squash (Cucurbita pepo L.), cabbage (Brassica oleracea L. var. capitata), broccoli (Brassica oleracea L. var. italica), collards, and cantaloupe (Cucumis melo L. reticulatus). A central plot of mustard transected the experimental area. To measure any effects of distance from the mustard, weekly sampling was performed at 5 equidistant intervals of 2.4 m to a distance of 12.2 m from the central mustard plot. Results showed whitefly attraction to squash and cantaloupes and aversion to mustard, with other crops (including collards), hosting intermediate insect densities. Repellent properties of mustard at these sampling distances in the field did not affect attraction or oviposition on other crops. It is possible that the sampling distances were too large to detect any repellent effects, or any effects of volatiles were stronger within the confines of the laboratory test arena. In general, results presented in this study are preliminary. Further field research needs to be conducted to determine if intercropping giant red mustard can be a promising strategy. However, squash and cantaloupe may have potential as trap crops for whitefly, or giant red mustard may be planted as a resistant crop when heavy whitefly infestations are anticipated.
Journal of Entomological Science
Vol. 45 • No. 3
Vol. 45 • No. 3