Influence of Tomato Planting Dates on Population Density of the Tomato Leafminer Tuta absoluta and its Associated Predatory Insects

Abstract

The tomato leafminer, Tuta absoluta is one the most important insect pests on tomato in both greenhouses and open field and can cause losses up to 80–100 % in tomato plants. Field study was carried out in a research farm located in Kafr El-Sheikh governorate during two successive years 2020 and 2021 to examine the influence of different tomato planting dates (February, June and September) on population density of T. absoluta and its predatory insects. The populations of T. absluta and its associated predators were affected by the date of plantation during both years. Using the direct count method, the highest peaks of T. absoluta larvae were recorded in June plantation during the first and second years (124 and 130 larvae/plant, respectively). Using male trap method, the highest peaks of T. absoluta male moths were recorded in June plantation during the first and second years (770 and 800 males/trap), respectively. By using both methods, September plantation of both years hosted the lowest average number of T. absoluta larvae and moths. In respect to the predatory insects of T. absoluta , the tomato bug, Nesidiocoris tenuis recorded the highest number in June plantation in the first and second years that represented by 300.0±70.5 and 286.9±89.9 individuals, respectively. Meanwhile, Coccinella undecimpunctata occupied the first rank in February plantation and represented by 3.4±0.7 and 3.0±0.5 individuals during the first and second years, respectively. September plantation came in the last category and recorded the lowest total average numbers of the predatory insects.