The Japanese beetle, Popillia japonica Newman, was accidentally introduced to the United States from Asia in the early 1900s. First detected in a New Jersey nursery, it is currently established in 28 states in the United States and has been detected in 13 additional states, 3 Canadian provinces, and at least 3 European nations. Adult beetles feed on over 300 host plant species, including many agricultural commodities such as fruits, field crops, and ornamentals, often causing severe economic damage. We discuss invasion history, ecology, biology, and management options for this invasive pest species in North America.

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The eastern larch beetle (Dendroctonus simplex LeConte) is the only tree-killing bark beetle that colonizes tamarack, or eastern larch, (Larix laricina (Du Roi) K. Koch) in the Great Lakes region. Historically, outbreaks have been intermittent and of short duration, frequently following predisposing factors such as drought or defoliation. However, over the past two decades, this insect has been in a perpetual state of outbreak in parts of the U.S. Great Lakes region, a deviation from historic norms. From 2001–2021, the insect impacted 300,000 ha, or 60% of the tamarack forests in Minnesota. This activity has prompted renewed interest in the beetle’s chemical ecology, including aspects of host semiochemistry. While foliar chemistry has been well documented in L. laricina, characterization of the monoterpene composition of the phloem has been lacking. We collected phloem samples from 56 tamarack trees across 14 locations in Wisconsin and Minnesota and assessed the relative abundances of the major monoterpenes present using gas chromatography-flame ionization detector (GC-FID). Individual terpenoid components identified included α-pinene (39.4%) and ∆-3-carene (30.0%) followed by several other components in small (<8%) amounts. This knowledge provides a basis for future testing of monoterpene synergists or antagonists in pheromone lures targeting eastern larch beetle and/or its natural enemies.

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] The benefits of sustainable soil management practices on soil health have been well documented for over a century. In 2017, 42,087,306 ha of farm land were cultivated with no-till practices, which reduce soil erosion. Crop rotation can also improve soil health by increasing soil nitrogen content. As nitrogen is a limiting factor to plant and insect growth, changes in soil nitrogen will likely affect plant-insect interactions. Furthermore, far fewer studies have examined long-term effects of soil management on insect communities. We examine the effects of longterm soil management practices (27 years) on soil nitrogen availability, foliar nitrogen content and secondary metabolites, and insect herbivory. We compare leaf-chewing insect growth and consumption rates feeding on tilled continuous, no-till continuous, tilled rotated, and no-till rotated plots containing soybean (Glycine max). While piercing-sucking insects were fed corn (Zea mays) kernels from rotated no-till or rotated tilled plots or soybean pods from rotated no-till or continuous till plots. Piercing-sucking insects experienced higher growth on continuous tilled corn in comparison to the soybean treatments, likely due to the senescence of the soybean pods. In 2018, soybean looper (Chrysodeixis includens Walker) feeding on continuously planted, tilled soybean had greater relative growth rates than those feeding on rotated, no-till soybean. However, in 2019, soybean looper consumption was higher on the rotated, no-till treatment than on continuous till soybean. Fall armyworm (Spodoptera frugiperda J.E. Smith) consumption and growth did not differ among treatments in both years. While percent soil nitrogen levels differed, our bioassay results led us to conclude that management practices that promote soil health such as no-tillage and crop rotation do not greatly influence insect herbivory. Additionally, for thousands of years, humans have artificially selected for yield in food crops. In recent years, this has become more critical as arable land has decreased while human populations have increased. Increase in yield influences plant physiology, photosynthetic rates, and nitrogen uptake. As plant growth has been selected for, plant defenses may have decreased, leading to potential increases in insect herbivore growth, consumption, efficiency of conversion of digested food, and efficiency of conversion of ingested food. We conducted bioassays feeding soybean looper (Chrysodeixis includens Walker) larvae leaves from 19 soybean cultivars released over the last 86 years. Larval growth was not affected by soybean release year, but consumption decreased on recent varieties. Efficiency of conversion of digested food and efficiency of conversion of ingested food also increased on more recent varieties, perhaps, because of differences in foliar nitrogen or terpenoids. This is important as selection for yield has not necessarily resulted in selection for higher insecticide application.