Prevalence, population dynamics and associated natural enemies of Tomato Leafminer, Tuta absoluta, in Egypt

The tomato leafminer (TLM), Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), is a devastating insect pest worldwide. As an invasive species, its spread depends on the suitability of biotic and abiotic factors. We documented the prevalence and population dynamics of TLM on tomatoes and other host plants along the Nile Delta region in Egypt. For the first time, we recorded Black nightshade as an alternative host plant. In tomato fields, males and immature stages fluctuated with crop phenological cycle, time, seasons and had 2-3 peaks/season. The effect of temperature and relative humidity on population dynamics is plant stage and season dependent. Visual inspection and trapped males were relevant indicators for population size. Tuta absoluta infested tomato leaves, fruits, and steams, with preference for leaves. Three predators; Nesidiocoris tenuis (Reuter), Macrolophus pygmaeus (Rambur) (Hemiptera: Miridae) and Chrysoperla carnea (Steph) (Neuroptera: Chrysopidae) and an egg parasitoid, Trichogramma achaeae (Nagaraja & Nagarkatti) (Hymenoptera: Trichogrammatidae) were recorded. Natural enemies corresponded to pest population fluctuations with higher incidence during the middle of the season. Activities of Tr. achaeae and N. tenuis were correlated with egg population in summer while M. pygmaeus correlated with larval population in winter. Exploring these ecological aspects provides key elements for pest control programs.