Host-Preference and Parasitic Capacity of Five Trichogramma Species (Hym.: Trichogrammatidae) against some Stored Product Moth Pests
Esmat Hegazi1, Cornel Adler2, Wedad E. Khafagi3, Essam Agamy4
1Alexandria University, Dept. of Entomology, Egypt
The host-preference and parasitic capacity of four local Trichogramma spp. towards four species of stored product moth eggs were investigated in laboratory experiments in order to select new candidate species for inundative releases against lepidopterous pests in storages. Experiments were carried out by offering a single parasitoid female to eggs of the Indianmeal moth Plodia interpunctella (Hubner), the Mediterranean flour moth Ephestia kuehniella Zeller, the warehouse moth E. elutella (Hubner), and the almond moth, Cadra cautella (Walker) in choice and no-choice assays. The Trichogramma species were collected from arid and semi-arid areas in Egypt. These were T. bourarachae, T. cordubensis, T. euproctidis, T. cacociae, and their efficacy was compared with the common wasp used commercially for biological control of stored product pests (T. evanescens).The bioassay for host-preference of Trichogramma was carried out by offering a single wasp female the choice between equal numbers of host eggs on square cards “Petri dish tests“ and /or strip cards “strip card tests”. In Petri dish tests, E. kuehniella was a highly acceptable host species for T. bourarachae, euproctidis, and cacociae wasps. While elutella and cautella eggs were more acceptable for evanescens and cordubensis, respectively. In strip card tests, E .kuehniella eggs were highly acceptable for bourarachae, cacociae and evanescens. Eggs of elutella and cautella were more acceptable for euproctidis and cordubensis, respectively. Also,the comparative study of parasitic capacity of the Trichogramma spp. was carried out under ‘no choice conditions' by exposing a freshly emerged single wasp to an unlimited number of host eggs. Significant differences were found among the parasitic capacity of the tested Trichogramma spp.: T. borarachae showed a good parasitic potential against S. cerealella and E. kuehniella; T. evanescens and T. cacociae against S. cerealella; T. cordubensis against S. cerealella and P. interpunctella and T. euproctidis against P. interpunctella. However, dissection of host eggs with wasp-emergence holes showed that all tested wasps had a propensity to superparasitise the host eggs. T. cordubensis, T. euproctidis and T. borarachae showed promise for further investigation into selecting new biological control agents against stored product lepidopterous pests.
Keywords: Parasitisation capacity, stored product moths, superparasitism, Trichogramma spp., host preference
Contact Address: Esmat Hegazi, Alexandria University, Dept. of Entomology, 21545 Alexandria, Egypt, e-mail: eshegazihotmail.com