Submitted to: Postharvest Biology and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/24/2017
Publication Date: 8/12/2017
Citation: Walse, S.S., Tebbets, J.S., Leesch, J.G. 2017. Postharvest fumigation of California table grapes with ozone to control Western black widow spider (Araneae: Theridiidae). Postharvest Biology and Technology. 134:1-4. doi:10.1016/j.postharvbio.2017.07.012.
Interpretive Summary: Western black widow spiders (BWS) are a pest of concern to fresh table grape packers and shippers from California. We report results from studies that examined the potential to control BWS with postharvest ozone fumigation. Results indicate that ozone fumigation can be used to control BWS and that the treatment does not result in quality damage to berries. Importantly, this research identifies a tool that the California table grape industry can use to simultaneously control decay as well as insect pests in fruit destined for export, which is often the most valuable of the season.
Technical Abstract: Ozone fumigations were evaluated for postharvest control of Western black widow spider (BWS), Latrodectus hesperus (Chamberlin and Ivie), in fresh table grapes destined for export from California USA. Mature adult female black widow spiders were contained in separate gas-permeable cages within a flow-through chamber and exposed for 1 h at 3 ± 1 °C to gaseous ozone at eight steady-state concentrations (i.e, [O3]ss) over the range 500 ± 25 to 12,000 ± 200 ppmv (uLL-1) with or without supplementation of atmospheric carbon dioxide levels, respectively 100,000 or ca. 300 ppmv [CO2]ss. Regression models of the concentration-response predicted = 98% mortality to adult female BWS populations following ozone fumigation for >1h at 3 ± 1 °C when headspace [O3]ss was maintained at 10,000 ppmv with ambient atmospheric CO2 levels ([CO2]ss = ca. 300 ppmv). A series of confirmatory fumigations were conducted for 1h at 3 ± 1 °C with headspace [O3]ss and [CO2]ss maintained at 10,000 ppmv and ca. 300 ppmv, respectively, which resulted in 0 survivors from 268 treated specimens, providing evidence to support the use of these treatment parameters for control of BWS in packed table grapes.