Pest invasion is one of the limiting factors affecting food production. Tomato leaf miner (Tuta absoluta) (Meyrick 1917) (Lepidoptera: Gelechiidae), is an invasive insect pest of tomato. However, In Kenya, there is limited information on the level of invasion of the pest in tomato producing areas in the country. We assessed the level of invasion of T. absoluta and farmer management practices in Kirinyaga County. Tomato farmers were interviewed using questionnaires aimed at identifying the management practices used by farmers to control T. absoluta and their awareness on the insect pest. Two hundred and eight tomato farmers were interviewed, 90% of the respondents rated T. absoluta as a major pest of tomato. Results show that 94% of the respondents use synthetic chemicals in the control of T. absoluta with an average frequency of 12 times per growing season of three months with the highest frequency being 16 times. Increased use of synthetic insecticides was associated with a negative impact on the natural enemies. Among the interviewed farmers, 52 and 46% of respondents stated that after chemical spraying natural enemies disappear and are killed respectively, while 2% did not know what happened to them. It is therefore imperative to design an integrated pest management program that integrates biological control and environmentally friendly chemicals for sustainable control of T. absoluta populations.

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.