With the detection of SLF in Windsor, area grape growers are worried about the impending invasion to their vineyards. The lanternfly has caused significant damage to severely, repeatedly infested vineyards in Pennsylvania, reducing Brix, yield, and vine health.
The article in National Geographic reported on preliminary research done at Penn State University and described the findings resulting from some citizen science. People reported dead SLF near milkweed plants. This set a series of greenhouse studies in motion. Lanternflies were caged with milkweed, grapevine, or nothing, and mortality was observed. Mortality was higher in the milkweed treatments than in plain starvation (nothing treatment). This suggested that something in the milkweed is toxic to lanternflies.
Because grapevine is one of the preferred hosts for lanternflies, the next step was to cage them with both grape and milkweed. While most of the insects chose grapevine for their food source, there was still mortality due to feeding on milkweed.
Sponsored by a Northeast SARE grant (LN25-494R), Dr. Flor Acevedo’s research group at Penn State University took this one step further and planted a strip of milkweed adjacent to three vineyards and monitored SLF infestations in vineyard borders with and without milkweed growing nearby. In the first year of establishment, her group hasn’t seen any difference in the SLF populations in the vineyards. However, the stand was young, and it was only one species of milkweed (swamp milkweed – Asclepias incarnata) that was planted. Dr. Acevedo’s group plan to continue to monitor the vineyards from the first year and also try common milkweed (Asclepias syriaca) in a denser stand in future trials.
Dr. Acevedo also cautions that things are more complicated in the real world. In the greenhouse trials, the insects were caged with milkweed for a minimum of 24 h while in the field, the insects can land on the plants and possibly feed but may leave immediately after. It is currently unknown how much milkweed sap the insects need to ingest for it to be lethal. Another possible constraint is that some milkweed species can be very invasive!
Even if the results aren’t fully confirmed, the researchers say planting milkweed is a great idea for a few reasons. For starters, there are dozens of species of milkweed native to the U.S., and each is important for native pollinators, including the monarch butterfly. While swamp milkweed wasn’t quite as effective at killing lanternflies as common milkweed, the former is preferred by farmers and gardeners because it doesn’t spread as willingly. (While milkweeds are native, they have historically been removed by farmers because of the way they can outcompete food crops.)
The bottom line – milkweed is beneficial because it helps support monarch butterfly populations. And it may be part of the toolbox for managing SLF, but its effectiveness has yet to be confirmed under field conditions. Stay tuned!
0 comments on “Milkweed vs Spotted Lanternfly – Too good to be true?”