Egg parasitoids of the genus Trichogramma (Hymenoptera, Trichogrammatidae) in olive groves of the Mediterranean region

Abstract

A survey of egg parasitoids of the genus Trichogramma (Hymenoptera, Trichogrammatidae) was carried out in olive groves in Portugal, Greece, Egypt, and Tunisia during the years 2002-2004. Parasitoids were obtained either by exposing sentinel eggs (Sitotroga cerealella Olivier or Ephestia kuehniella Zeller) on olive trees or by collecting eggs of lepidopterous olive pests. Parasitized egg samples were reared separately in the laboratory for emergence of parasitoids. These were further reared in separate lines and processed by morphological and molecular biology techniques for species characterization. The recorded fauna of Trichogramma parasitoids in olive groves was species poor and consisted of species mainly known from the Mediterranean region. Trichogramma bourarachae Pintureau and Babault was found in Tunisia and Egypt, T. cordubensis Vargas and Cabello, and T. euproctidis Girault in Egypt, Trichogramma cacoeciae Marchal in Portugal, Greece, Egypt, Tunisia and Trichogramma nerudai Pintureau and Gerding in Portugal. Apart from that, Trichogramma oleae Voegelé and Pointel was collected in Tunisia. This species is probably not indigenous, but has established after several releases of a French strain were made in recent years. For selected strains, the sequence of the internal transcribed spacer 2 (ITS-2) region of rDNA was determined and deposited in the GenBank database. Differences in important biological attributes were found among collected strains of T. bourarachae, suggesting the existence of biotypes. The results contribute to the limited knowledge on distribution and biodiversity of the genus Trichogramma in the Mediterranean region. They can be helpful for the preservation and use of indigenous Trichogramma species in biological control of lepidopterous pests in olive and other local crops.

A molecular key to the common species of Trichogramma of the Mediterranean region

“…As far as we are aware, this latter species has only been found commonly in tomato crops in Portugal. Similarly, T. nerudai may be limited to Portugal, since the natural distribution of T. nerudai is South America, and its presence in Portugal is unusual since no known releases of this species have taken place (Herz et al 2007). Also in Portugal the species T. brassicae has not been found in tomato fields.…”

Temperature and strain effects on reproduction and survival ofTrichogramma oleaeandTrichogramma cacoeciae(Hymenoptera: Trichogrammatidae)

“…It was found in the Netherlands (Vavre, De Jong, and Stouthamer 2004), in France on the eggs of L. botrana (Volkoff and Daumal 1994), and in Germany on baits hung in plum trees (Schö ller and Hassan 2001). It was also collected in olive groves in Portugal, Greece and Egypt (Herz et al 2007). In North Africa, Trichogramma cacoeciae was found in Morocco (Pintureau and Babault 1988).…”

Attraction of DifferentTrichogrammaSpecies toPrays oleaeSex Pheromone

“…They are currently used successfully in inundative and inoculative releases worldwide (Smith 1996, van Lenteren 2000. In the Mediterranean area where olives (Olea europea L.) are widely cultivated, Trichogramma fauna in terms of number of species was found to be relatively poor, and natural parasitism rates of the eggs of key olive pests in olive groves by Trichogramma wasps are low (Herz et al 2007). Yet, six Trichogramma species were found in olive groves in different countries of the Mediterranean basin.…”