Evaluation for Potential <I>Trichogramma</I> (Hymenoptera: Trichogrammatidae) Strains for Control of the Striped Stem Borer (Lepidoptera: Crambidae) in the Greater Mekong Subregion

Abstract

Trichogramma species and strains differ significantly in host specificity and performance. Nine Trichogramma strains, six of them collected from paddy fields in the Greater Mekong Subregion, were evaluated for performance on eggs of the striped stem borer, Chilo suppressalis (Walker), in both laboratory and field tests to determine potential Trichogramma strains that can be used in an inundative release in an integrated pest management program. In the laboratory glass vial tests, all strains showed higher parasitism rates on 0-24-h eggs than on the two older age groups (24-48 and 48-72 h). Wasp emergence rate was also higher from parasitized 0-24-h striped stem borer eggs, while Trichogramma immature duration was significantly prolonged on 0-24-h striped stem borer eggs. Parasitism rates differed among Trichogramma strains, with Trichogramma chilonis Ishii CJ strain showing significantly higher parasitism rate than any other strains. In the field tests, parasitism of sentinel striped stem borer eggs by Trichogramma strains released at 50,000, 100,000, and 200,000 wasps per hectare was low, with marginal yet significant differences between strains. The highest parasitism was achieved by T. chilonis CJ strain at the high and medium release rates. Hence, it can be concluded that T. chilonis CJ strain released at 100,000 wasps per hectare may be a cost-effective control tactic for field releases targeting striped stem borer.

<b>Biological parameters of three <i>Trichogramma pretiosum</i> strains (Riley, 1879) (Hymenoptera: Trichogrammatidae) on eggs <i>Helicoverpa armigera</i> (Hübner, 1805) (Lepidoptera: Noctuidae)

“…Similar percentages of parasitism, between 81 and 56% were obtained by (Bueno, Parra, & Bueno, 2012), By evaluating 13 Trichogramma strains in Chrysodeixis includens (Walker, 1958) eggs (Lepidoptera: Noctuidae). Ko et al (2014) had results that were similar to the present study, when evaluating a strain of T. pretiosum on eggs of Plutella xylostella (Linnaeus, 1758) (Lepidoptera: Plutellidae). Öztemiz (2008) observed an efficiency between 66 and 90% in the parasitism of H. armigera using T. euproctidis (Giralt, 1911) (Hymenoptera: Trichogramatidae) with cotton cultures in field conditions.…”

<b>Age and density of eggs of <i>Helicoverpa armigera</i> influence on <i>Trichogramma</i> pretiosum parasitism

“…In addition, once the hardening of the chorion limits the penetration of the ovipositor, the parasitoids requires a longer manipulation of the host resulting in fewer parasitized eggs (Faria, et al, 2000). The parasitism of older eggs forces the larva of the parasitoid to grow faster (Pizzol et al, 2012) The emergency reduction of the parasitoids due to the embryonic development was noted by several authors (Ko et al, 2014;Pastori, Monteiro, Botton, & Pratissoli, 2010;Poltronieri, Silva, Araujo, Schuber & Pastori, 2008). Among the factors that influence the emergence of parasitoids are: humidity, size, age and the egg nutritional quality.…”

“…Therefore, it is fundamental to know the relationship suitable between number of parasitoids to be released in relation to the density of host eggs presented in the agroecosystem, and the host-egg age more favorable to parasitism, in order to determine the release intervals of the parasitoid in the field (Ko et al, 2014;Polanczyk, Pratissoli, Holtz, Pereira, & Furtado, 2007). Thus, the aim of this study was to evaluate the effects of H. armigera egg age and density on biological characteristics of Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae).…”

Selectivity of pesticides used in rice crop on Telenomus podisi and Trichogramma pretiosum

“…The Telenomus and Trichogramma genera stand out as egg parasitoids of stinkbugs and lepidopterans that are being used for biological control in rice crops (Ko et al 2014). Telenomus podisi Ashmead (Hymenoptera: Platygastridae) is a generalist species that parasitizes a wide range of hosts.…”

“…Some of the hosts are the eggs of the Asiatic rice borer Chilo suppressalis (Walker) (Lepidoptera: Crambidae) (Chen et al 2010, Ko et al 2014, the rice leafroller Cnaphalocrocis medinalis (Guenee) (Lepidoptera: Pyralidae) (Gurr et al 2012) and the rice yellow stem borer Scirpophaga incertulas (Walker) (Lepidoptera: Crambidae) (Guo et al 2002), among others. In Brazil, several species of Trichogramma have been described (Querino & Zucchi 2003), and Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) is one of the most used for controlling Lepidoptera pests (Brugger et al 2010, Stefanello Júnior et al 2012.…”