Research recently published in the Journal of Economic Entomology has offered new insight into managing the tomato leaf miner (Tuta absoluta) using entomopathogenic nematodes (EPN). If the pest is not adequately managed, it can cause up to 100% crop loss in both field and green-house grown tomatoes. Also causing further concern is the increasing insecticide resistance the pest has shown to be developing.
The tomato leaf miner originated in South America but has also been identified in Eastern Spain and many other European countries throughout the Mediterranean basin, as well as the Middle East and Sub-Saharan Africa. Its four larval stages mine through leaves, shoots, stems, flowers and developing fruit. Although the larvae usually reside inside the mines, they can also leave to start a new mine on different parts of the plant and by the mature, fourth stage, they mostly drop to the ground for pupation to occur. In optimal conditions, the pest can develop up to a dozen generations per year.
At the moment, management of the tomato leaf miner is mainly based on monitoring with sex pheromone traps and synthetic pesticides. However, since the pest has such a short development period with a number of generations each year, it requires multiple insecticide applications per season. This is harmful on the other, nearby wildlife and further, is the cause of insecticide resistance in the leaf miner. The authors of the study recommend that in order to minimize the negative environmental impacts and reduce insecticide resistance rates, an integrated pest management (IPM) strategy is needed.
In this study they examined the effect of temperature, soil type, and exposure time on the efficacy of the EPN species Steinernema carpocapsae and Heterorhabditis bacteriophora against tomato leaf miner larvae. EPNs have already been used as a biological control agent against a wide variety of insect pests and a number of products based on EPN species are already used in IPM programmes. The results of the study clearly indicate the potential of both EPN species for the control of larvae in greenhouse-grown tomatoes. See the full article for a comprehensive breakdown of these results.
The research concludes that both species of EPN could be combined into an effective alternative to synthetic insecticides.
Other research also recently published in the same journal looks into how the tomato leaf miner’s natural enemy Pseudapanteles dignus can be used as a biological control agent in both tomato and aubergine plants.
To find out more about how the tomato leaf miner affects farmers, watch Elias Kamuga’s story; a smallholder farmer from the Mount Kenya region who lost almost 90% of his crop due to Tuta absoluta.