Understanding Tuta absoluta
Tuta absoluta, also known as the tomato leaf miner or tomato pinworm, is a species of moth belonging to the Gelechidae family. It poses a significant threat to tomato cultivation in various regions of Kenya, including parts of Kirinyaga, Embu, Loitoktok/Kajiado, and the Lower Eastern areas. This pest not only presents a challenge for growers but also contributes to over 20% of post-harvest yield losses in tomatoes.
The life cycle of this pest consists of four distinct stages: egg, larvae, pupa, and adult. The adults lay their eggs on the underside of leaves or fruits. Upon hatching, the larvae penetrate the leaves, where they feed and develop. They create large galleries, burrow into stalks, and consume apical buds, green fruits, and ripe fruits. The damage inflicted by these larvae can lead to complete crop loss, reaching up to 100%. The pupae, usually measuring 5-6mm in length, are cylindrical and initially have a greenish color that darkens as they approach adulthood.
The adult moths themselves measure about 6-7 mm in length and possess filiform antennae. They are characterized by grayish to silvery scales. Typically, these moths are nocturnal and remain hidden during the day. They disperse to crops by flying.
Tuta absoluta exhibits a wide range of hosts within the solanaceae family; however, its primary and favored host is the tomato (Lycopersicon esculentum). Additionally, this pest affects other crops such as nightshades, potatoes, eggplants, pepinos, peppers, and tobacco.
Effective pest management is crucial to prevent complete crop losses and maintain pests at manageable levels. Various methods, including both chemical and cultural approaches, are employed. However, the rapid development of resistant strains in both the larvae and adults poses a significant challenge.
Field hygiene plays a critical role in the overall pest control strategy. This involves proper disposal of crop debris and remains, as well as maintaining a clean field and its surroundings.
Crop rotation with non-solanaceae plants has proven to be an essential practice in breaking the pest cycle outlined earlier.
Chemical control methods continue to offer a fast and reliable means of pest management. These measures commence early in the crop season and are consistently applied to deter moths and eliminate destructive larvae.
One highly regarded systemic product for larval elimination is Occasion Star® 200 SC, which is applied at a rate of 5mls per 20 liters of solution, mixed with Integra® at a rate of 3mls per 20 liters. To effectively combat adult moths, proper management involves alternating the use of Occasion Star® 200 SC with Lexus® 247 SC at a rate of 8mls per 20 liters. Occasion Star® 200 SC is an enhanced insecticide that acts as both a contact and stomach poison, providing broad-spectrum control against chewing insect pests such as caterpillars, leafminers, bollworms, webworms, budworms, leafworms, fall armyworms, thrips, and spider mites in agricultural crops.