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ABSTRACT
Comparative study of parasitic capacity and longevity of three local Trichogramma spp.; T. cordubensis and T. euproctidis from arid area and T. borarachae from a semi-arid area, collected from olive groves in Egypt, was carried out under laboratory conditions at 25±0.5°C. Significant differences were found among the parasitic capacity of the tested Trichogramma spp. It was 80.1±3.5 for T. borarachae versus 60.2±2.5 for T. cordubensis and 73.2±2.7 for T. euproctidis. In all species, parasitism was highest in the first day. Longevity of Trichogramma females was studied by exposing freshly emerged wasps to different feeding regimes as follows: 1) combination of honey and host eggs, 2) honey only and 3) no honey or hosts. The longevity experiments indicated that feeding conditions significantly affected the survival period of the wasp females. In all species, the longevity of honey-fed non ovipositing females was significantly longer. In the absence of food source all species showed the shortest longevity. In general, parasitoid longevity under each feeding condition was species dependent.
Key words: Olive groves, Trichogramma spp., parasitic capacity, longevity.
INTRODUCTION
Egg parasitoids of genus Trichogramma are keystone natural enemies of many lepidopterous pests in agriculture and forestry (Li, 1994). More than 150 different species are known from various biotypes (Pinto, 1999). These minute parasitoids were considered excellent indicator species to study the side effects of pesticides on beneficial arthropods and the environment (Hassan, 1998). At present, the European Plant Protection Organization (EPPO) listed the species; Trichogramma brassicae Bezdenko, T. cacoeciae Marchal, T. dendrolimi Mastamura, and T. evanescens Westwood for use in countries of Euro-Mediterranean region (EPPO, 2002). Preference should always be given to indigenous strains or species that are collected from the same regions when developing a new biocontrol program based on Trichogramma (Van Lenteren et al., 2003).
Diversity of locally occurring egg parasitoid species in Africa has not been adequately assessed (Sithanatham et al., 2001). At least three trichogrammatid species are known to occur in Egypt. These are Trichogramma evanescens (Ahmed and Kira, 1960); T. buesi (Abbas, 1989) and Trichogrammatoidae bactrae (El-Hafez and ElHafez, 1995) parasitizing some lepidopterous pests other than olive and jasmine moths. T. bororachae, T. cordubensis, T. nr. pretiosum and T. cacociae were the four naturally occurring Trichogramma species recorded through the period 2001-03...