Supressing populations of tomato leaf miner (tuta absoluta) in the agro-ecological zones of Morogoro

Abstract

Tomato leaf miner Tuta absoluta is a destructive and highly invasive insect pest of tomato and other solanaceous plants including plants in the family Fabaceae like beans. The range of host for the moth is extensive requiring in-depth surveys on both solanaceous and Fabaceae crops along with weeds to fully understand it. This study was aimed at understanding the spatiotemporal distribution of the moth along the Uluguru Mountains in Morogoro. The moth preference to alternative hosts and also efficacy of selected bio and synthetic insecticides in the management of the moth was also evaluated. From the results it was revealed that T. absoluta was present in all locations of the study in varying numbers. Weather factors such as rainfall and temperature had influence in the population of the moth. Population of the moth was determined by using delta traps loaded with para-pheromones on a sticky card that captured male moths. Trapping of the moth was conducted for 12 weeks for two growing seasons, 21 traps were used to trap the male moth for each season. Some weeks during trapping a high average population of 300 male moths were trapped while the lowest average population was 20 moths per week. Population fluctuation was observed to be influenced by the altitude of the location of trapping. Host preference was determined by sampling of plant leaves with visible damage of Tuta absoluta larva; The sampled leaves were placed in a plastic box with sand. Tomato (Solanum lycopersicum L), Eggplant (Solanum melongena), African eggplant (Solanum aethiopicum) and Amaranthus (Amaranthus retroflexus) were sampled in Morogoro Municipality and Mvomero district. Amaranthus was the least preferred of the host plants sampled compared to Tomato and Egg plant. Efficacy of synthetic and bio synthetic insecticides was determined in three locations using a synthetic insecticide Wiltigo and a combination of bio-insecticide Antario and recharge, Biotrine and recharge. The applied insecticides proved to be equally capable of controlling the moth in the field.