Pathogenicity of Selected Native Entomopathogenic Nematodes against Tomato Leaf Miner (Tuta Absoluta) in Kenya

Abstract

Tomato leafminer, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) has been an important pest in Kenya since it was reported in 2014. It is adversely affecting tomato production in the country. The objective of this study was to evaluate the pathogenicity of Kenyan EPNs namely; Heterorhabdities sp. and Steinernema karii against Tuta absoluta larvae under laboratory conditions in petri dish bioassays. Entomopathogenic nematodes were obtained from Kenya Agricultural and Livestock Research Organization EPNs laboratories and Tuta absoluta larvae were obtained from a colony reared and maintained in a greenhouse at Kabete Campus Field Station, Nairobi. The effect of EPNs concentrations on Tuta absoluta larvae mortality exposed for 24-72 hours was evaluated. An experiment laid out in a complete randomized design with four replicates was conducted. The results showed that the evaluated concentration rates of Heterorhabditis sp. and Steinernema karii at 100, 300 and 500 Ijs/ml significantly (p Tuta absoluta larvae compared to control and that the highest mortality was recorded at 500 Ijs/ml having been exposed for 72 hours. Steinernema karii was more pathogenic compared to Heterorhabditis sp. throughout the exposure period of 24-72 hours, having achieved 100% and 91.5% larval mortality, respectively. This study demonstrates that native EPNs have a potential for management of the tomato leaf miner (Tuta absoluta) which can be exploited.