Integrated disease and vector management of alfalfa mosaic virus in Chile peppers

In 2019, Alfalfa mosaic virus (AMV) (Martellivirales: Bromoviridae) was discovered in southern Colorado and has caused significant losses for chile pepper farmers. AMV is a non-persistently transmitted virus spread by several aphid (Hemiptera: Aphididae) species that move transiently through fields, probing into plants and transmitting the virus without habitually feeding. For this reason, chemical management is not a viable tactic for this system. The goal of this work was to test the non-consumptive effects of aphid predators in combination with a putatively resistant chile pepper cultivar and assess the synergistic interactions between these two integrated pest managements tactics on both conventional and organic fields. On a research farm at Colorado State University, a split-split-plot experiment was implemented to examine the non-consumptive effects of Orius insidiosus (Hemiptera: Anthocoridae) on aphids and AMV transmission in chile peppers. The whole-plot factor was farming system, the split-plot factor was biocontrol (presence or absence of O. insidiosus), and the split-split factor was cultivar (putatively resistant or susceptible cultivar). Natural enemy releases occurred in treatments plots following planting of pepper plants. AMV incidence and severity were recorded twice throughout the summer–once in July and again in August. Leaf tissue was also collected for enzyme-linked immunosorbent assays (ELISAs) to determine the proportion of plants testing positive for the virus. Starting in mid-August, yield for both cultivars was collected until the end of the season. This continued project provides valuable information to help producers make better informed management decisions about future chile pepper production in Colorado.