Location: Vegetable Crops ResearchTitle: Newly discovered bio-control agents kill Sparganothis and cranberry fruitworm: Preliminary data on native nematode species Author
Submitted to: Cranberry Crop Management Newsletter
Publication Type: Trade Journal
Publication Acceptance Date: 9/18/2015
Publication Date: 9/18/2015
Citation: Foye, S., Steffan, S. 2015. Newly discovered bio-control agents kill Sparganothis and cranberry fruitworm: Preliminary data on native nematode species. Cranberry Crop Management Newsletter. 28(9):102. Interpretive Summary:
Technical Abstract: Historically, two of the most destructive insect pests in Wisconsin have been the Cranberry Fruitworm (CFW) and the Sparganothis Fruitworm (SFW). Once they’ve hatched, controlling them is a lot like “trench warfare,” where we throw various weapons at the enemy, but most of them miss. Many Wisconsin growers are interested in supplementing their insecticide applications with alternative control tactics. A recent survey of nematode species in central Wisconsin’s wild cranberry habitat may have provided such an option. Three (3) strains of entomopathogenic nematodes have been recovered from Jackson County, Wisconsin. The nematodes were collected by a standard bioassay technique from moss-covered soils and peat, in close proximity to wild cranberry plants. All three nematode strains have been shown to attack Sparganothis Fruitworm, and all seem similar in their virulence (ability to kill the host). Based on preliminary trials, these nematodes are quite virulent, killing over half the SFW within just three days of treatment, at doses less concentrated than typical nematode applications. At higher doses and longer host exposure-periods, host mortality rises dramatically, but our early trials are aimed at simply showing that the nematode can kill SFW. It remains to be seen whether or not these 3 nematode strains will be an effective bio-control agent for SFW, but given that the nematodes in our trial had to search out their prey before killing them, there is reason to be optimistic. In the case of the Cranberry Fruitworm (CFW), one of the three nematode strains was able to kill larvae and/or pre-pupae that had finished feeding, tunneled into cotton, and spun a pupal case. What’s interesting about this particular nematode strain is that in order for it to get access to the CFW larva, it had to crawl through the thick pupal case first. After penetrating the defenses of CFW, the nematode infects the caterpillar, consumes it, and spills out in the thousands. So far, this particular nematode strain is the only one that kills both SFW and CFW.