Over the past month we have found existing populations of kudzu bugs to be reproducing and increasing in size on kudzu vines. At sites where we had previously found only scattered adults, there are now greater populations of all life stages, including eggs and nymphs. Adult kudzu bugs are also apparently on the move, and have been detected in northern Prince George's County near Greenbelt. We have yet to detect the insects making the leap across any borders to establish in any new counties in Maryland.
We have sampled a total of 30 different kudzu patches across eight counties in Maryland. Most of the sites are roadside patches of vines, but a couple are off the main roads in parks, neighborhoods, and agricultural fields. The northernmost sites we have sampled include patches of kudzu vines in Howard and Baltimore Counties around the Triadelphia Reservoir and Catonsville. Other patches have been spotted off of busy highways, such as I-495, I-270, and I-95, but these sites are generally unsafe to be sampled and have been left alone. We have yet to find any patches of kudzu to sample in counties on the mid and lower Eastern Shore of Maryland but we are still searching.
The next, ongoing phase of this summer's project is to monitor whether the kudzu bug moves into crops like soybeans before overwintering. For this stage of the project, we are monitoring plots of edible soybean plants (edamame) on research farms across the state. Edible soybeans are vegetable crops that produce a soft, green bean, while the soybeans conventionally grown in Maryland produce a harder seed used as feed for livestock and for vegetable oil production. Edible soybeans are thought to be more attractive to the kudzu bug than conventional soybeans grown as field crops. So far we have not detected any stages of the insect on the edible soybeans or other soybean plants grown on research farms. Through the remainder of the summer, we will expand the scope of our sampling to include fields outside of the Maryland research farms. Our sampling efforts will be combined with those of other research teams investigating the abundance of another invader, the brown marmorated stink bug (Halyomorpha halys) in soybean fields across Maryland.
By the end of the summer, we expect to have documented the distribution of this new invasive species within the state of Maryland, and to make predictions for the impact this insect will have on Maryland's agriculture in the future. The ongoing surveys of kudzu vine patches will help to monitor the spread of the insect from southern counties into more northern areas. As a perennial vine, these patches will be around again next year, and knowledge of the locations of these sites will allow more effective monitoring of the spread of the insect. Our surveys of soybean fields will help to determine whether this insect poses a serious threat to Maryland agriculture, and whether Maryland farmers will need to look out for this insect in future seasons.