Insect Pest - Beetles

Over the past few years, harvesting of some Maryland and Eastern U.S. grapes has been complicated by the presence of Multicolored Asian Ladybeetles (MALB - Harmonia axyridis). The adult beetles can damage fruit in the field but most importantly, acts as a contaminant of the harvest, “fatally” tainting the wine made from the grapes.

There exists a lack of control efficacy information to enable decision-making about which organic insecticide product works best for a given insect pest. Here we summarize results of 153 field trials on the control efficacy of common active ingredients in organic insecticides against groups of the most difficult to control insect pests. The performance of organic products Entrust (spinosad), Azera (pyrethrin and azadirachtin), PyGanic (pyrethrin) and Neemix (azadirachtin) varied widely among pest groups, as well as among pest species within a group, providing an overall reduction in pest infestations by 73.9%, 61.7%, 48.6% and 46.1%, respectively.

August IPM insect scouting tips on soybean, field corn, and sorghum.

Entomopathogens are bacteria, fungi, protozoans or viruses that can infect and subsequently cause disease in insects and other arthropods. They can indirectly impact cropping systems by serving as naturally suppressors of insect and mite pests. When there are epizootic outbreaks, entomopathogens are capable of causing rapid declines in large populations of their arthropod hosts. Many of these naturally occurring pathogens have been formulated and commercialized as insecticides.

I was at a farm the other day that had a wide variety of crops on it and the grower showed me what we at first thought were odd-looking Colorado potato beetle larvae in their tomatillos, but they did not really look like CPB.

Normally at this time of year when I talk about any insect problems in crucifers I talk about harlequin bugs that feed by sucking out plant juices and inject toxins into the plant. But I have seen several fields and even some high tunnels with blister beetles feeding and defoliating several different vegetables such as tomato (including the fruit), leafy greens, crucifers, spinach and especially swiss chard (fig. 1). Blister beetles begin feeding on the edges of leaves eventually leaving only stems (fig. 1). The presence of blister beetles now is not unusual as they are often found in large clusters in late summer-early fall. They can arrive in large groups, seemingly overnight and can do a great deal of damage in a short period of time.

Grape Flea beetles, Altica spp. (Coleoptera: Chrysomelidae), are small (4-5 mm), oval shaped, metallic blue-purple beetles that jump when disturbed.

The previous “Timely Viticulture” addressed some basic information on MALB and this message will concentrate on management tactics. Some sections of this message were intentionally repeated, but there is new information throughout.

Soybean: Scout for the usual defoliators, including bean leaf beetle, Japanese beetle, and caterpillars. The treatment threshold is 15-20% defoliation for bloom to pod fill. Note that defoliation percentages should be based on the entire soybean plant or canopy, not just the top leaves or worst leaves. University of Nebraska Extension has a nice guide for defoliating insects in soybeans (https://croptechcafe.org/defoliating-insects-in-soybeans-thresholds-training-and-tools/). Adult Dectes Stem Borer will be emerging over the next several weeks. Chemical control is not recommended since it would require multiple applications to reduce larval infestations, which is not economical. However, if a high number of adults are found, harvesting that field as soon as it matures will reduce losses associated with lodged plants.

Timely Viticulture is an electronic newsletter designed to remind grape producers of seasonal vineyard needs and considerations throughout the year.