Exploring Varietal Mixtures as a Strategy for Sustainable Management of Insect Pests Associated with Cabbage [Brassica oleraceaVAR. capitata L. (Brassicaceae)]

Abstract

Cabbage is a highly nutritious vegetable, yet faced with pest challenges. At present, synthetic pesticides are the major control measure and this has some side effects such as; resistance by pest, adverse effect on non-target organisms and hazardous effects on environment. All these problems bring the sustainability of ecosystem to danger. Exploring varietal mixture of cabbage as an alternative for sustainable pest management of cabbage was investigated during the rainy (April, – August 2020) and dry (November, 2020 – March, 2021) seasons. Treatments consisted of Purple-ball, GloriaF1, Oxylus (sole each and mixture) in ratio 1:1 respectively, all raised in nursery beds and transplanted to treatment plots, given a total of 7 treatments, all laid out in a Randomized Complete Block Design (RCBD) with three replicates each. The insect associated with the crop were sampled using sweep net, pitfall traps and the mechanical hand-picking methods. The phytochemical components of each variety were also carried out. Results showed that cabbage which was mixed with purple-ball variety showed reduced attack by insects as compared with Gloria and Oxylus planted sole. This could be attributed to the higher value of cardiac glycoside, tannins, steroids and anthraquinone in Purple-ball variety than other varieties. These compounds are responsible for plant defence which may have caused the low insect population in Purple-ball variety. The yields from Purple-ball variety plots in both seasons were however significantly lower compared with other varieties in both seasons. Notwithstanding, the yield from the mixture of purple-ball with other varieties was not significantly different from others. Therefore, the inclusion of Purple-ball variety in GloriaF1 and Oxylus production is recommended as this may serve as a natural defence against insect pests. Also, the use of this cropping system is not only effective but inexpensive and safe for human health and the environment relative to synthetic insecticides.