Population of Tuta absoluta and natural enemies after releasing on tomato grown greenhouse in Turkey

Abstract

The study was conducted to evaluate the population of tomato leafminer, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) and efficiency of natural enemies on tomato grown greenhouse in Mediterranean Region of Turkey during 2010 and 2011. Trichogramma evanescens Westwood (Hymenoptera: Trichogrammatidae) and Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae) were used for biological control of the pest. Both the egg parasitoid and preadatory bug were released alone and combined. The decrease of egg and larva numbers of T. absoluta were higher in plots released T. evanescens with N. tenuis together than each one released separately. However, the decrease of eggs was higher than larvae in plots released N. tenuis and T. evanescens alone. Population of T. absoluta and fruit numbers were influenced by the treatments. The number of fruit directly affected negatively by increasing the population density of T. absoluta. The trial demonstrated that it was necessary to establish N. tenuis population at the starting of the crop season with Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs, atleast two or three weeks ago, and together with parasitoid release, had a better significant reduction of T. absoluta population to reach maximum number of fruits. INTRODUCTİON Recently, Tuta absoluta has spread very quickly in Turkey, as well as in Mediterranean countries. Tuta absoluta first reported in Turkey in 2009 (Kilic, 2010), and is now posing a serious threat on tomato production. Tomato plants may be attacked at any development stage from seedlings to mature plants. The potential damage could lead up to 100% yield loss without control measure (EPPO, 2005). Larvae feed between the epidermal layers on leaves, causing irregular mines. This mining protects the larvae from getting in contact with insecticides and decreases the effects of chemical control. So, an alternative management approach is urgently needed. One possible solution is the use of biological control agents. More than 20 species of parasitic wasps have been described for T. absoluta (Luna et al., 2007). One of them is the egg parasitoid Trichogramma species (Medeiros et al., 2006). Trichogramma species are the most widely used as biocontrol agents in the world and they are effective against lepidopteran eggs such as the lifeminer, T. absoluta. Furthermore, several species of predators have been evaluated as biological control agents mainly the mirid bugs Nesidiocoris tenuis (Reuter) and Macrolophus pygmaeus (Rambur) (Urbaneja et al., 2009). Both nymph and adult stages of N. tenuis are prey on T. absoluta eggs and larval stages. It is also able to feed on the plants when the prey population is low and Nesidiocoris population is high. T. absoluta population and natural enemies with efficacy of these biological control agents after releasing are unknown in our country. The objective of the study is to evaluate the population of T. absoluta as well as T. evanescens and N. tenuis after releasing against pest on greenhouse-grown tomato of Mediter-ranean Region, Turkey. The preliminary results are presented in the study.