Dispersal ofTrichogramma ostriniae(Hymenoptera: Trichogrammatidae) in Potato Fields

Abstract

The dispersal ability of Trichogramma ostriniae Pang and Chen, a biological control agent of Ostrinia nubilalis Hübner, was studied in commercial potato fields on the Eastern Shore of Virginia. The purpose was to quantify dispersal of T. ostriniae after an inundative release to aid in determining the number of release points needed per unit area for effective biological control of O. nubilalis in solanaceous crops. A single release of approximately 0.5 million wasps was made in two spatially separate potato fields in summer 2005 and 2006. Each release area contained 25 monitoring points at distances from 5 to 45 m from the release point bearing a yellow sticky card and O. nubilalis egg sentinels to observe for adult parasitoids and parasitism, respectively. Results showed that movement of T. ostriniae adults from the release point was rapid with individuals captured at 45 m within 1 d of emergence. High rates of parasitization (20-50%) also were observed at this distance, but the levels decreased with increasing distance from the release point. The distances that encompassed 98% recaptured T. ostriniae adults (x(98)) were 27.5 and 12.9 m from the release point in 2005 and 2006, respectively. The (x(98)) distances for parasitization of O. nubilalis were 21-26 m in 2005 and 8-10 m in 2006. However, the highest levels of parasitization in both years occurred nearest the release point. T. ostriniae showed uniform dispersal within an area of approximately 0.1 ha, indicating that multiple release points should be used for effective dispersal of T. ostriniae and control of O. nubilalis in solanaceous crops. Based on the assumption that a distance of 16 m represents the radius around a release point in which T. ostriniae activity was at its maximum, we estimate that approximately 12 release points/ha would be required in potato fields.

Trichogramma pretiosumparasitism and dispersal capacity: a basis for developing biological control programs for soybean caterpillars

“…Different from the dispersion capacity observed for T. pretiosum in soybean fields in our results, Chapman et al (2009), studying the dispersal capacity of T. ostriniae in potato fields, observed that this species dispersed rapidly over large distances, successfully moving throughout a 0.4-ha area of potatoes and reproducing at 45 m from the releasing point four days after the release. Chapman et al (2009) results are similar to what was reported for the same parasitoid species in sweet corn by Wright et al (2001). The differences from our results to the literature might be due to both the different studied species, but more probably are due to the differences in crop architecture and plant density in the field.…”

Possible effects of inter-specific competition on the coexistence of two parasitoid species:Trichogramma brassicaeBezdenko andChelonus oculator(F.) (Hymenoptera: Trichogrammatidae, Braconidae)

“…oculator (0.009-0.341). In this sense, it must be pointed out that Trichogramma species present proper and quick -and even higher -direct dispersion (Chapman et al 2009) particularly if performed through phoresy (Fatouros et al 2005). Nevertheless, it must be pointed out that there may be differences between the amounts of devoted time among the patches (data not available for these species).…”

Microdot technology for individual marking of small arthropods

“…For pest control, measurements of pest insect dispersal are essential for establishing the scale over which management should operate, identifying suitable habitat and assessing connectivity between populations (Mahroof et al , 2010), whereas quantifying population densities and survivorship allows the effective monitoring of management outcomes. Data on the movement of introduced control agents for biological control of pests or weeds is also crucial for predicting their spread from release points (Corbett & Rosenheim, 1996; Bianchi et al , 2009; Moerkens et al , 2010), monitoring their populations and predicting impacts on nontarget species (Rudd & McEvoy, 1996; Chapman et al , 2009). Conservation of beneficial insects requires dispersal data to delimit management units and the movement of pollinator species is also becoming increasingly important for restoration of pollinator services in degraded ecosystems (Menz et al , 2010), as well as assessing the risks of engineered genes escaping from genetically‐modified crops (Ellstrand, 2003).…”