Studies on evaluation of Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae) preying on invasive insect pest Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) and its damage to tomato plant

Abstract

Recently, in India severe incidence by the invasive insect pest, the South American tomato pinworm, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) was reported for the first time infesting tomato crop in Pune, Maharashtra. Later infestation was reported in the other states of India. In T. absoluta i nfested tomato field, zoophytophagous mirid, Nesidiocoris tenuis (Reuter) was observed to be associated with tomato pinworm. A net house experiment was conducted to evaluate N. tenuis on T. absoluta infested tomato plants. The aim was to ascertain, if releases of N. tenuis could reduce T. absoluta infestation or due to its phytophagous nature it could lead to damage of tomato plants. The treatments comprised of a) release of N. tenuis on T. absoluta infested plants, b) releases of N. tenuis on uninfested plants and c) T. absoluta infested plants were maintained as control. Results indicated that in treatment with N. tenuis , number of T. absoluta eggs and the % mined area were lesser by 83.25% and 89%, respectively. Overall number of necrotic rings per plant during all 10 weeks caused by N. tenuis was significantly lesser in T. absoluta infested plants treated with N. tenuis (0.74±0.18) compared to treatment with N. tenuis alone (2.16±0.35). Flower abortion was also not observed at this density (total release of 6 adults/plant). When mean number of T. absoluta eggs were high in 3rd week (9.54 eggs/plant) number of necrotic rings were negligible though average number of N. tenuis was 4.1/plant during the same week. During 5th week when number of N. tenuis was on peak (11.2/plant), the average numbers of T. absoluta eggs and necrotic rings were 3.61eggs/plant and 0.46/ plant, respectively. It shows that number of necrotic rings per plant increased with decreasing T. absoluta population. Further studies are needed to investigate the precise role of N. tenuis as a natural mortality factor of T. absoluta in field situations and its damage potential after a long interaction with plant in pest scarcity and when it occurs at high density.