Selection of suitable trichogramma strains to control the codling mothCydia pomonella and the two summer fruit tortrix mothsAdoxophyes orana, Pandemis heparana [Lep.: Tortricidae]

Abstract

Simple laboratory methods to select candidate Trichogramrna strains for use in biological control were tried. 17 strains were screened for their suitability against the codling moth Cydia pomonella L. as well as the 2 summer fruit tortrix moths Adoxophyes orana F.R. and Pandemis heparana Schiff. In one set of experiments, the capacity of Trichogramma to parasitize each of these target pests was examined, in another set, the preference of Trichogramma to contact and parasitize the target pests compared to the standard mass rearing host Sitotroga cerealella was assessed in choice experiments.A strain of Trichogramma dendrolimi from the People's Republic of China was found to have the highest fecundity with all the 4 hosts tested. In choice experiments, however, this strain was shown to have a near equal preference between the target tortrix pests C. pomonella, A. orana and the replacement host S. cerealella, il local Trichogramma strains collected from fruit orchards and vineyards in different locations in the Federal Republic of Germany were reared separately. Four of these local strains, one identified as T. embryophagum, showed clear preference to the tortrix pests C. pomonella and A. orana compared to S. cerealella. The preference of one of these strains was particularly strong and amounted to a near total rejection ofS. cerealella eggs in the presence of any of the 2 tortrix pests.The remaining 12 strains had weaker parasitization capacity and/or less preference to the target pests. Four of the strains tested in these experiments, including T. dendrolimi and T. embryophagum, were mass reared and released in apple orchards between 1984 and 1986. The results of these field experiments are planned to be published in this journal.

Biologia e parasitismo de Trichogramma atopovirilia Oatman & Platner e Trichogramma pretiosum Riley (Hymenoptera, Trichogrammatidae) em ovos de Spodoptera frugiperda (J.E. Smith) (Lepidoptera, Noctuidae)

“…Em geral, a freqüência de contacto em ovos de S. frugiperda foi maior do que em ovos de A. kuehniella, contribuindo para o aumento no número de ovos de S. frugiperda parasitados por T. atopovirilia e T. pretiosum. Estudos feitos por HASSAN & GUO (1991) e WÜHRER & HASSAN (1993, mostraram a perda ou a diminuição na preferência pelo hospedeiro natural quando Trichogramma é criado por várias gerações sobre o hospedeiro alternativo o que, segundo HASSAN (1989), é um indicativo da perda de eficiência no campo. Assim, T. atopovirilia e T. pretiosum mantiveram a preferência pelo hospedeiro natural mesmo tendo sido criadas por várias gerações no hospedeiro alternativo, e mantiveram, portanto, a agressividade e eficiência de parasitismo em ovos de S. frugiperda.…”

“…A preferência hospedeira foi avaliada adotando-se a metodologia de HASSAN (1989). Ovos de A. kuehniella e S. frugiperda foram distribuídos em diagonal, em pequenas áreas (0,4 mm 2 ) de uma arena de cartolina azul (20 mm 2 ) colocada no interior de um tubo de vidro (8,5 x 2,5 cm), no centro da qual foi oferecida uma gota de mel puro.…”

Parasitism of Helicoverpa assulta Guenee (Lepidoptera: Noctuidae) eggs by Trichogramma spp. (Hymenoptera: Trichogrammatidae): Implications for inundative release on tobacco plants

“…Trichogramma species/strains are known to show different preferences for certain host eggs (Hassan, 1989;Hassan and Guo, 1991;Wang et al, 1995). In selecting elite egg parasitoid species or strains, laboratory bioassay methods, including glass tube bioassay and mesh cage bioassay, are usually employed and have been proved effective (Hassan, 1989).…”

Identification of suitable Trichogramma sp. and working-out dosages for management of Brinjal Shoot and Fruit Borer under laboratory condition

“…The selection of most promising species or strains of Trichogramma has been advocated as first step in achieving successful control program (Hassan, 1989). In order to select most promising species for evaluation against brinjal shoot and fruit borer, L. orbonalis, six species of trichogrammatids like Trichogrammatoidea bactrae, Tr.…”