D3043: Evaluation of feeding and development of a biocontrol agent of Vincetoxicum spp. (Hypena opulenta), fed V. nigrum foliage infected by a leaf spot pathogen

Vincetoxicum nigrum and V. rossicum, black and pale swallow-worts, are vining perennial plant native to Europe that are invasive in North America. It is difficult to remove fully and left unmanaged forms dense monocultures that outcompete and smother native plants, quickly becoming problematic in agricultural settings and natural areas. A biological control program was developed for Vincetosicum spp. using Hypena opulenta, a defoliating moth species that was the first swallow-wort biological control agent approved for field releases in the United States in 2017. From 2018 onwards, an unknown fungal pathogen or pathogen complex has been observed in Rhode Island at Hypena opulenta release sites. This pathogen causes leaf lesions and plant dieback. To examine if the unknown fungal pathogen affects larval development of Hypena opulenta, no-choice feeding tests will be performed. In a no-choice development experiment, Hypena opulenta first instar larvae will be collected and placed in individual Petri dishes, with either infected or uninfected (control) V. nigrum leaves. Head diameter will be measured at each instar and pupal weights will be recorded, as well as percent survival to each instar. This will determine the impact infected V. nigrum foliage has on Hypena opulenta larval development and survival.