A tale of two seasons for spotted wing drosophila – Good Fruit Grower

—by Matt MilkovichMichigan State College tree fruit entomologist Julianna Wilson shares tales about noticed wing drosophila administration through the Nice Lakes Fruit, Vegetable and Farm Market EXPO in December. (Matt Milkovich/Good Fruit Grower)Julianna Wilson had tales to inform in regards to the noticed wing drosophila, the invasive fruit fly that’s develop into a significant pest of North American berries and cherries, when she spoke on the 2024 Nice Lakes Fruit, Vegetable and Farm Market EXPO in December.The Michigan State College tree fruit entomologist’s first story targeted on two biocontrol brokers, the samba wasp and ronin wasp, and their potential to handle SWD populations. One other was a story of two years, 2023 and 2024, and the climatic variations in Michigan that led to low SWD infestation the primary 12 months and excessive infestation the second 12 months. BiocontrolsThe samba wasp (Ganaspis brasiliensis) and ronin wasp (Leptopilina japonica) each originated in Asia, the place they parasitize SWD. The wasps adopted the fruit fly to North America and are beginning to set up populations within the U.S. Each wasps parasitize SWD by laying their eggs inside SWD larvae which might be growing in fruit. The wasp larvae enable the SWD larvae to turn into pupae, then they devour the SWD, utilizing the pupae case to guard themselves whereas they turn into adults, Wilson mentioned. MSU researchers reared and launched a small variety of samba wasps in 2022. The wasps had been launched after harvest alongside the wooded edges of cherry and blueberry plantings, the place SWD usually take refuge, she mentioned.They didn’t get well any samba wasps in 2022, however they launched 37,000 wasps at 30 websites the next 12 months and recovered wasps from 5 of them (none of them cherry websites, nevertheless), she mentioned. SWD infestation was “horrible” in Michigan in 2024, Wilson mentioned, however researchers hoped the silver lining can be higher institution of the pest’s pure enemies. They launched extra samba wasps that 12 months, although at fewer websites. They hadn’t recovered any samba wasps by Dec. 11, however they had been nonetheless processing samples. They had been nonetheless processing samples from ronin wasp launch websites, too, and had already discovered wasps in two out of 14 cherry websites. “That’s actually thrilling,” Wilson mentioned. “It looks as if it’s increase in quantity.”The position of climateMichigan noticed very low SWD infestation in 2023. The SWD inhabitants didn’t begin to surge till late July that 12 months, properly after cherry and blueberry harvest had began. In 2024, nevertheless, there already was an abundance of SWD within the area by late June, which contributed to the poor high quality of final 12 months’s Michigan cherry crop. So, why the distinction? For one factor, 2023 had extra days under 41 levels Fahrenheit (SWD’s exercise threshold) than did 2024, which delayed the pest’s inhabitants improvement. Better rainfall in 2024 most likely elevated SWD populations that 12 months, as properly, she mentioned. That distinction made Wilson marvel: Can winter temperatures and spring rainfall quantities be used to foretell SWD populations for the approaching season? And might that prediction be used to information spraying selections? Maybe growers can apply fewer sprays in lower-risk years. Wilson’s lab will deal with these and different questions with funding assist from the Agricultural Local weather Resiliency Program, a brand new partnership supported by MSU, the Michigan Plant Coalition and the Michigan Division of Agriculture and Rural Growth. Any probability to make use of fewer pesticides might assist keep away from the looming specter of SWD growing insecticide resistance. California researchers are beginning to discover proof of resistance to pyrethroids in SWD populations, in addition to organophosphates and spinosad. MSU researchers haven’t but detected SWD resistance in Michigan, however the genetic potential is there and will begin to be expressed with heavy use of pesticides over time, Wilson mentioned. One other solution to keep away from resistance is by discovering viable options to sprayable pesticides. A Missouri firm, Agragene, now produces sterile SWD males by way of genetic engineering. When sterile males mate with wild SWD females, the females’ eggs don’t develop. Sterile SWD males aren’t but registered to be used, although there have been trials in Oregon, and MSU researchers hope to check them quickly, she mentioned.Appeal to-and-kill know-how — a bait station set out early within the season that kills numerous SWD earlier than they begin damaging fruit, for instance — affords one other potential various, nevertheless it’s been exhausting to discover a bait or odor supply robust sufficient to beat SWD’s want to put eggs in fruit. With funding help from the U.S. Division of Agriculture, Wilson’s lab is learning yeast-based, species-specific pesticides that might be mixed with identified attractants to be extra alluring to SWD, she mentioned. •



Source link