Effect of Cabbage and Basil intercropping on conservative biological control of Aphids

Abstract

Conservative biological control seeks to preserve beneficial organisms as the natural enemies of pests through habitat management. These studies aimed to measure the potential of basil (Ocimum basilicum L.) in the biological control of aphids in green cabbage (Brassica oleraceae L. var. acephala); and to evaluate the influence of the intercropping on green cabbage productivity. In an organic commercial crop of green cabbage in Águas Claras, RS, basil was used as an associated border (BB) and contrasted with plants in beds with no border (WB). We compared Aphididae density and parasitism, in the spring/summer seasons of 2016 and autumn/winter of 2017. Brevicoryne brassicae L. and Myzus persicae Sulzer (Hemiptera, Aphididae) were recorded in the green cabbage, in 2016. A mean of 13.8 ± 8.72 aphids/leaf was recorded in the WB, significantly higher than in the BB, 3.4 ± 1.83 (Tukey 5% p = 0.00002). In the 2017 season, this difference was not significant at 10.3 ± 12.73 (WB) and 6.9 ± 11.34 (BB). The mean of parasitized aphids was 2.8 ± 2.84 in WB and 9.9 ± 2.87 BB (p = 0.0041) in the spring crop and 2.9 ± 4.10 (WB) and 14.25 ± 7.3 (BB) in the winter (p = 0.0039). The association of green cabbage and basil had an area equivalence index (AEI) in 2016 = 1.07 and 2017 = 0.99 indicating that basil did not affect green cabbage yield.