Build-up of insect pests and their natural enemies on rotated and non-rotated okra (Abelmoschus esculentus (L.) Moench), tomato (Lycopersicon esculentus Mill) and egg plant (Solanum melongena (L.) Moench.) fields

Abstract

Objective: The quest for increased food production requires crops to be protected from pests and diseases. The readily available means of controlling pests is the application of chemical pesticides, with its attendant negative effects on humans and the environment. The study was conducted to assess the effectiveness of crop rotation as a pest control measure and how this affects the population of natural enemies of the pests.

Methodology and Results: The build-up of insect pests’ of tomato, okra and eggplant and their natural enemies on rotated and non-rotated fields were studied. The rotated and non-rotated fields were each replicated 3 times. The different insect pests that infested the crops were identified and counted. Aphids and whiteflies were assessed using a scoring scale from 0 to 5. Natural enemies of the pests were also identified and counted. Significantly, larger numbers of Bemisia tabaci, Aphis gossypii, Podagrica uniforma, Zonocerus variegatus and Locusta migratoria were sampled on the crops on the non-rotated than the rotated fields. Numbers of natural enemies, Dictynia sp Coccinella sp and Camponotus sp were not significantly different on the rotated and non-rotated fields but crop yields were significantly higher on the rotated field.

Conclusion and application of findings: The results of the study indicated that rotating crops on the same piece of land resulted in reduction in pests’ numbers and an increase in crop yields. The reliance on pesticides alone to manage pests may not be the best option to reduce pests because of the negative effects of pesticides on the environment. Crop rotation can therefore be adopted as a cultural control option in the overall management of pests.