Host-preference and parasitic capacity of new candidates of Trichogramma species (Hym.:Trichogrammatidae) against some stored product moths

Abstract

The host-preference and parasitic capacity of some local Trichogramma spp. (T. bourarachae, T. cordubensis, T. euproctidis and T. cacociae) towards four species of stored product moth eggs were investigated in order to select new candidate species for use in mass rearing and biological control against moths in storages. The efficacy of the Trichogramma spp. was compared with T. evanescens, the common wasp used commercially for biological control. 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. Two different choice experiments were used to certify the same conclusion in both methods. The bioassay for host-preference of Trichogramma was carried out by offering a single early female wasp 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, T. euproctidis, and T. cacociae wasps while E.elutella and C.cautella eggs were more acceptable for T. evanescens and T.cordubensis, respectively. In strip card tests, E.kuehniella eggs were highly acceptable for T.bourarachae, T.cacociae and T.evanescens. Eggs of E.elutella and C.cautella were more acceptable for T.euproctidis andT. cordubensis, respectively. 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. All tested wasps had a propensity to superparasitize the host eggs. T. cordubensis, T. euproctidis and T. borarachae showed promise for further investigation into selecting new biological control agents against some stored product lepidopterous pests.