Abstract
Combination of pest management strategies that minimize pesticide use and conserve natural enemies is important for a sustainable environment. Overreliance on synthetic insecticides in the management of Tuta absoluta has led to pesticide resistance leading to difficulties in managing the pest. In this regard, alternative measures need to be put in place to reduce the effects of this pest. The objective of this study was, therefore, to assess the effectiveness of host plant resistance, biological control, and selective insecticides when used in combination, in the management of T. absoluta in tomato production. The study was set up in a greenhouse in a completely randomized design involving two tomato varieties, an insecticide (chlorantraniliprole), and a biological control agent(Macrolophus pygmaeus), applied singly or in combination. Data were collected on T. absoluta damage from the lower, intermediate, and upper leaves. The results from this study show that a combination of insecticide with a moderately resistant variety had a significantly lower T. absoluta damage as compared with a susceptible variety combined with an insecticide. However, the moderately resistant variety when combined with insecticide showed no effect when the biological control agent was added. The susceptible variety significantly reduced T. absoluta damage when combined with the biological control agent. These results indicate that treatment combinations in insect pest management can be utilized. The present study results indicate that using a moderately resistant variety (Riogrande VF) in combination with the insecticide chlorantraniliprole (Coragen®) and a susceptible variety (Pesa F1) in combination with the biological control agent (M. pygmaeus) can improve T. absoluta management. Under good habitat management, the susceptible variety will perform equally as the moderately resistant variety due to suppression of the T. absoluta populations by natural enemies. These findings show the importance of environmental conservation both by enhancing natural enemy abundance and use of selective insecticide in the management of T. absoluta in tomato production. Combinations in this present study are likely to reduce insecticide doses, thereby reducing the cost of production and enhancing environmental compatibility with natural enemies.
Highlights
Combining control methods has been found as the best control option for highly damaging pest species [1]
E results from this study show that a combination of the insecticide with a moderately resistant variety (MR + I) reduced T. absoluta damage as compared with the susceptible variety combined with the insecticide (S + I). is implies that insecticide susceptibility of T. absoluta is affected by the level of
Macrolophus pygmaeus has been shown to be an effective predator against T. absoluta under greenhouse conditions
Summary
Combining control methods has been found as the best control option for highly damaging pest species [1]. Integrated pest management (IPM) tries to minimize environmental impact of pesticides by combining various control strategies such as biological control, cultural practises, resistant varieties, and pesticides in a compatible manner to keep pests below economically injurious levels [2, 3]. Synthetic insecticides can be effective in the control of pest outbreaks. Their often broad spectrum effects have detrimental impacts on both beneficial organisms and the environment [5]. Insecticides should reduce insect pest populations to a level below economic injury rather than aim at eradication. Effective insecticide application results in high and rapid insect mortality. Complete dependence on insecticides can lead to pest resistance or resurgence and is, not sustainable [6]
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