Population dynamics and insecticide resistance in Tuta absoluta (Lepidoptera: Gelechiidae), an invasive pest on tomato in Kenya.

Tuta absoluta feeds on solanaceous plants with preference on tomato. Management of the pest is mostly with chemical insecticides. This study identified insecticide resistant populations and predicted resistance to insecticides. Insecticide resistance development was modelled using system thinking, and system dynamics approaches. The model showed the pest resistance development is alarming with an exponential increase of the resistance strength mostly in recent years. Furthermore, we used seven insecticide-resistance gene markers to resolve the population structure and genetic differentiation of insecticide-resistant populations in Kenya. The genes for resistance (knockdown resistance (kdr) mutations, acetylcholinesterase (AChE) and voltage gated sodium channel (para)) were detected in all populations. Population structure analyses separated T. absoluta populations into three genetic clusters with resistant genes that are interconnected. A better insight on the population dynamics and the genetic structure T. absoluta resistant genes in Kenya will help estimate resistance strength and determine the most effective pest control strategies.