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Onion thrips, Thrips tabaci Lindeman, is a worldwide pest of onion whose feeding damage and transmission of Iris yellow spot virus (IYSV) may reduce onion yields. Little is known about the seasonal dynamics of T. tabaci dispersal, the distance of dispersal, or the movement of thrips infected with IYSV during the onion-growing season. To address these questions, T. tabaci adults were collected using transparent sticky card traps in commercial onion fields three times during the onion-growing season (June, July, and late August) at varying heights above the canopy (0.5-6m above soil surface) and with trap-equipped unmanned aircraft (UAVs) flying 50-60m above onion fields during August sampling periods in 2012 and 2013. Randomly selected subsamples of captured T. tabaci were tested for IYSV using RT-PCR. Most T. tabaci adults were captured in late August and near the onion canopy (<2m) throughout the season. However, 4% of T. tabaci adults captured on sticky cards were at altitudes ≥2m, and T. tabaci were also captured on UAV-mounted traps. These data strongly suggest that long-distance dispersal occurs. More T. tabaci captured on sticky cards tested positive for IYSV in August (53.6%) than earlier in the season (2.3 to 21.5% in June and July, respectively), and 20 and 15% of T. tabaci captured on UAV-mounted traps tested positive for IYSV in 2012 and 2013, respectively. Our results indicate that T. tabaci adults, including viruliferous individuals, engage in long-distance dispersal late in the season and likely contribute to the spread of IYSV. [ABSTRACT FROM AUTHOR]

Field efficacy of 2 strains of entomopathogenic nernatode, Heterorhabditis bacteriophora Poinar, were examined against alfalfa snout beetle larvae, Otiorhynchus ligustici (L.), in an established alfalfafield. Both strains wereapplied at 2.5 and 15billion IJs per hectare using 2 different spray nozzle configurations. H. bacteriophora 'NC' reduced the insect larval population to 0.33--2.3 larvae per 54,900 cm3, significantly below the levels in the untreated controls, and reduced the incidence of snout beetle larval feeding and alfalfa stand death. NC occurred in 23--70% of the soil cores during the 1st growing season, but did not persist beyond the 1st growing season. The high rate of H, bcateriophora 'Oswego' reduced the insect larval population to 1.3 larvae per 54,9W cm3, significantly below the levels of the untreated controls but not as low as NC. Oswego also reduced the incidence ofsnout beetle larval feeding and alfalfa stand death. Oswego could be found in 73--99% of the soil cores during the Ist growing season and persisted for the entire 700 d of the trial. After 700 d, Oswego could be found in 24--44% of the soil cores taken within the treated plots. Evidence of nematode recycling was observed in both nematode strains. Data suggests that the NC strain would be more appropriate in situations where a biopesticide is desired, and the Oswego strain is more appropriate where long-term insect suppression is desired within more stable ecosystems. [ABSTRACT FROM AUTHOR]