Seasonal Occurrence of Key Arthropod Pests and Beneficial Insects in Michigan High Tunnel and Field Grown Raspberries

Insect Visitors of Specialty Cut Flowers in High Tunnels

Various strategies incorporate floral resources into agricultural landscapes to support beneficial insects. Specialty cut flower production offers a rarely explored approach to offer floral resources while yielding a marketable product for growers. We characterized insect visitation to six species of specialty cut flowers. Due to Wyoming's growing conditions, the flowers were grown in high tunnels, thus offering insight into insect abundance in this unique semi-controlled environment. The flower species tested were Calendula officinalis, Celosia argentea, Daucus carota, Helichrysum bracteatum, Matthiola incana, and a Zinnia elegans-Zinnia hybrida mixture. At least four species were in bloom from early June through late September. The flowers attracted diverse pollinator groups including Diptera, Hymenoptera, Coleoptera, and Lepidoptera. Bees most often visited Ca. officinalis, H. bracteatum, and Celosia spicata whereas flies most often visited D. carota. Bombus were the most oft-collected bees from the flowers and were found on all six cut flower species. Wasp abundance varied little across the cut flowers, but wasp community composition was distinct. The highest diversity of wasp families was collected from the Zinnia mixture (seven families) in contrast to less diverse collections from Ce. spicata (two families). The most abundant wasp families collected were Crabronidae and Sphecidae. Our experiment documented that ornamental cut flower species attract pollinator insects into high tunnel environments. All cut flower species tested were visited by multiple types of beneficial insects. Planting a mixture of specialty cut flowers can support insect diversity while also diversifying on-farm agricultural products through sale of cut flower stems.

Known and Potential Invertebrate Vectors of Raspberry Viruses

The estimated global production of raspberry from year 2016 to 2020 averaged 846,515 tons. The most common cultivated Rubus spp. is European red raspberry (Rubus idaeus L. subsp. idaeus). Often cultivated for its high nutritional value, the red raspberry (Rubus idaeus) is susceptible to multiple viruses that lead to yield loss. These viruses are transmitted through different mechanisms, of which one is invertebrate vectors. Aphids and nematodes are known to be vectors of specific raspberry viruses. However, there are still other potential raspberry virus vectors that are not well-studied. This review aimed to provide an overview of studies related to this topic. All the known invertebrates feeding on raspberry were summarized. Eight species of aphids and seven species of plant-parasitic nematodes were the only proven raspberry virus vectors. In addition, the eriophyid mite, Phyllocoptes gracilis, has been suggested as the natural vector of raspberry leaf blotch virus based on the current available evidence. Interactions between vector and non-vector herbivore may promote the spread of raspberry viruses. As a conclusion, there are still multiple aspects of this topic that require further studies to get a better understanding of the interactions among the viral pathogens, invertebrate vectors, and non-vectors in the raspberry agroecosystem. Eventually, this will assist in development of better pest management strategies.

Insect Exclusion Screens Reduce Cucumber Beetle Infestations in High Tunnels, Increasing Cucurbit Yield

As high tunnel vegetable production acreage increases in the United States, so does the need for management strategies tailored to their unique growing environment. Cucumbers are an ideal crop in these systems; they can be vertically trellised to maximize the production area and provide high yields to balance the increased costs associated with high tunnel construction. One of the most limiting factors in cucurbit production in general is the cucumber beetle complex and the bacterial pathogen they transmit. In this study, we investigated the optimal size of netting installed on high tunnels to prevent cucumber beetle colonization while maintaining ventilation to reduce heat stress. Of the three mesh sizes investigated across 4 yr, the intermediate mesh with a pore size of 0.72 × 0.97 mm was optimal to exclude cucumber beetles, maintain ventilation, and produce the highest yields for both cucumber and melon plants. The smallest (0.16 mm2) and intermediate mesh sizes resulted in secondary pest outbreaks (e.g., aphids), which did not occur in open tunnels and to a lesser extent in tunnels covered with the largest (1.00 × 4.00 mm) mesh. Despite these secondary pests, yield was higher in small- and intermediate-sized mesh treatments due to relief from cucumber beetle infestations, including striped (Acalymma vittatum Fabr. (Coleoptera: Chrysomelidae)) and spotted (Diabrotica undecimpunctata howardi Barber (Coleoptera: Chrysomelidae)) beetles. Overall, we conclude that insect exclusion netting is an effective method to exclude cucumber beetles from high tunnels, but mesh size should be carefully considered when weighing the collective effects on yield and primary/secondary pest abundance.