Comparative efficacy of Macrolophus melanotoma (Costa) (Hemiptera: Miridae) and M. pygmaeus (Rambur) (Hemiptera: Miridae) against Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) eggs on tomato and Dittrichia viscosa L. (Greuter)

Abstract: Macrolophus melanotoma (Hemiptera: Miridae) is a predator naturally occurring on the non-crop plant Dittrichia viscosa, with a potential in pest control on tomato. However, its predation rate on Tuta absoluta has not been examined. In this work the consumption of T. absoluta eggs by M. melanotoma 5th instar nymphs was recorded on a tomato leaflet and a D. viscosa leaf placed together in a Petri dish. On each leaf different egg densities (20-20, 40-40, 60-0 and 0-60) had been placed. In the second part of the experiments, the consumption of M. melanotoma was recorded by releasing one female per cage in which a single tomato plant with 14 or 60 eggs of T. absoluta. Then, in choice-experiments, the consumption of M. melanotoma or M. pygmaeus females were investigated by releasing a single female in a cage with one tomato and one D. viscosa plant, adding 30 T. absoluta eggs on one of them. In each treatment 10 replicates were conducted at 25 ± 1 °C, 65 ± 5 % RH, 16:8 L:D. The number of eggs that M. melanotoma consumed was non-significantly different when 60 eggs placed on D. viscosa or tomato leaflet. In the treatments where eggs had been placed in both leaves it consumed higher number of eggs on the leaf of D. viscosa. In the no-choice experiments in cages, M. melanotoma consumed 6.8 ± 0.78 and 20 ± 0.81 eggs on tomato plants with 14 and 60 eggs. The egg consumption of M. melanotoma on tomato plants in cages with a D. viscosa plant reached about half that of M. pygmaeus, while the reversed occurred when eggs were placed on D. viscosa. Therefore, M. melanotoma can locate and consume at a comparatively high rate the eggs of T. absoluta on tomato leaflets in dishes and on tomato plants even in the presence of D. viscosa plants.