Understanding factors influencing distribution and density of a micro-Lepidoptera moth, Tuta absoluta (Gelechiidae) and its impact in tomato agroecological zones of Tanzania

Abstract

Field survey was conducted from August to November 2016 and repeated from January to April 2017 to study population, distribution and damage by tomato leaf miner (TLM) (Tuta absoluta Meyrick 1977) in 156 farms in agroecological zones of Tanzania. A pheromone trap/farm was deployed in tomato or other Solanaceae’s crops for examining moth of T. absoluta stuck in each trap and to determine damage by TLM. Results indicated that TLM is present in 13 regions with the highest population in Southern zone (Iringa), Northern zone (Arusha) and East-Central (Morogoro) with catches averaging 357.8±25.5, 279.9±12.1, 298.7±11.4 and 173.1±10.1 moths/trap in dry season respectively whereas lowest count amounting 13.3±1.0moths/trap was observed in western zone (Mwanza) during rainy season. Tomato was the most damaged crop with high mines averaging 90.0 ± 0.0% damage in Iringa and the low of 30.0±5.7 % realized in Mwanza. Tuta absoluta was found attacking 10 more plant species besides tomato with damage incidence averaging 83.3 ± 3.7% in Solanum lycopersicum, 60.0±0.0% in Solanum tuberosum, 30.0±0.0% damage in weed (Solanum incanum) and the lowest damage averaging 0.0±0.0% was observed in capsicum annuum. Based on these findings, it is evident that, T. absoluta is expanding its geographical range and hosts resulting into high damage and yield loss affecting farmers’ livelihood in Tanzania. This study informs farmers on the proper use of pheromone traps for early detection, scouting, weeding, crop rotation, use of biological control agents for effective management of the pest to reduce losses and environmental impact due to extensive use of synthetic pesticides.