Oviposition and Calling Behavior of Codling Moth (Lepidoptera: Tortricidae) in the Presence of Codlemone

The effect of the major component of codling moth, Cydia pomonella (L.) sex pheromone (codlemone, E,E-8,10-dodecadien-l-ol) on female calling and oviposition behavior was investigated. Calling by virgin females was similar between moths placed in sealed containers containing codlemone or codlemone-free air. However, when pheromone emitted by females was removed by a continuous air stream, calling in codlemone-permeated air was significantly higher than in clean air. The temporal pattern of calling was unaltered by the presence of codlemone. In a laboratory no-choice test, oviposition rates by codling moth females were similar in the presence of codlemone and in codlemone-free air. However, in paired-choice tests, females deposited more eggs on uncontaminated waxed paper surfaces than on codlemone-contaminated surfaces

Compatibility of Intercropping with Mechanized Agriculture: Effects of Strip Intercropping of Pinto Beans and Sweet Corn on Insect Abundance in Colorado

The potential for management of insect pest densities by regulation of crop diversity through intercropping was examined in sweet corn and pinto beans. Insect abundance was monitored in corn and beans in alternating multiple-row patterns of 1, 2, 4, 8, and 16 rows. Insect responses to intercropping treatments were variable, with positive, negative, and neutral responses observed, depending on species of insect and crop. In some cases, insect abundance was affected by strip-intercropping widths of up to eight rows, suggesting that strip intercropping may be compatible with some types of mechanized agriculture

Effect of Starch-Based Corn Rootworm (Coleoptera: Chrysomelidae) Baits on Selected Nontarget Insect Species: Influence of Semiochemical Composition

Various starch-encapsulated semiochemical-insecticide formulations, developed for potential use in adult corn rootworm (Diabrotica spp.) management programs, were evaluated in the laboratory and field for effectiveness on corn rootworm beetles: a carabid, Harpalus pennsylvanicus DeGeer; and a coccinellid, Coleomegilla maculata lengi Timberlake. Carbaryl was formulated in pregelatinized starch matrices along with Diabroticaspecific semiochemicals. The specific combination of feeding-gustatory stimulants encapsulated within or coating the outside of starch granules significantly influenced effectiveness. Allstarch formulations containing feeding-gustatory stimulants effectively killed Diabrotica virgifera virgifera LeConte adults in laboratory and field bioassays. However, H. pennsylvanicus and C. m. lengi mortality was greatly reduced when presented with starch granules coated with buffalo gourd (Cucurbita foetidissima H.B.K.) root powder (contains cucurbitacin E, I, and E-glycoside) or purified cucurbitacin I. Cucurbitacin I and component(s) of buffalo gourd root powder appear to be C. m. lengi and H. pennsylvanicus antifeedants. In the field, significantly more C. m. lengi and D. v. virgifera were collected at traps baited with pollen-coated than root powder-coated starch granules. When granules were broadcast over plants, mortality of C. m. lengi was greater in plots receiving pollen-coated than root powder-coated granules whereas the opposite was observed for corn rootworm beetles. Data suggest that to optimize the effectiveness of starch baits against D. v. virgifera and to minimize adverse effects on C. m. lengi and H. pennsylvanicus, granules coated with cucurbitacin rather than with starch or pollen should be used in corn rootworm management programs

Compatibility of Intercropping with Mechanized Agriculture: Effects of Strip Intercropping of Pinto Beans and Sweet Corn on Insect Abundance in Colorado

The potential for management of insect pest densities by regulation of crop diversity through intercropping was examined in sweet corn and pinto beans. Insect abundance was monitored in corn and beans in alternating multiple-row patterns of 1, 2, 4, 8, and 16 rows. Insect responses to intercropping treatments were variable, with positive, negative, and neutral responses observed, depending on species of insect and crop. In some cases, insect abundance was affected by strip-intercropping widths of up to eight rows, suggesting that strip intercropping may be compatible with some types of mechanized agriculture

Pyrethroid Exposure Reduces Growth and Development of Monarch Butterfly (Lepidoptera: Nymphalidae) Caterpillars

Insecticide exposure has been identified as a contributing stressor to the decline in the North American monarch butterfly Danaus plexippus L. (Lepidoptera: Nymphalidae) population. Monarch toxicity data are currently limited and available data focuses on lethal endpoints. This study examined the 72-h toxicity of two pyrethroid insecticides, bifenthrin and β-cyfluthrin, and their effects on growth and diet consumption. The toxicity of bifenthrin to caterpillars was lower than β-cyfluthrin after 72 h. Survival was the most sensitive endpoint for bifenthrin, but diet consumption and caterpillar growth were significantly reduced at sublethal levels of β-cyfluthrin. Using AgDRIFT spray drift assessment, the aerial application of bifenthrin or β-cyfluthrin is predicted to pose the greatest risk to fifth-instar caterpillars, with lethal insecticide deposition up to 28 m for bifenthrin and up to 23 m for β-cyfluthrin from treated edges of fields. Low boom ground applications are predicted to reduce distances of lethal insecticide exposure to 2 m from the treated field edge for bifenthrin and β-cyfluthrin. Growth and survival of fifth-instar monarch caterpillars developing within the margins of a treated field may be significantly impacted following foliar applications of bifenthrin or β-cyfluthrin. These findings provide evidence that pyrethroid insecticides commonly used for soybean pest control are a potential risk to monarch caterpillars in agricultural landscapes

Cardenolide, Potassium, and Pyrethroid Insecticide Combinations Reduce Growth and Survival of Monarch Butterfly Caterpillars (Lepidoptera: Nymphalidae)

The monarch butterfly, Danaus plexippus L., has evolved to be insensitive to milkweed cardenolides via genetic modifications of Na+/K+-ATPase. There is concern for insecticide exposures near agriculture, with little information on monarch caterpillar toxicology. It is unclear how cardenolide insensitivity may affect the sensitivity of monarch caterpillars to pyrethroid insecticides. Additionally, potassium fertilizers may affect monarch caterpillar physiology and cardenolide sequestration. Here, we investigated the growth, survival, and development of caterpillars exposed to the cardenolide ouabain, bifenthrin, and potassium chloride (KCl) alone and in combination. Caterpillars were either exposed to (1) ouabain from third- to fifth-instar stage, (2) KCl at fifth-instar stage, (3) KCl and bifenthrin at fifth-instar stage, or (4) combinations of ouabain at third-instar stage + KCl + bifenthrin at fifth-instar stage. Caterpillar weight, diet consumption, frass, and survival were recorded for the duration of the experiments. It was observed that 1–3 mg ouabain/g diet increased body weight and diet consumption, whereas 50 mg KCl/g diet decreased body weight and diet consumption. Caterpillars feeding on KCl and treated with 0.2 μg/μl bifenthrin consumed significantly less diet compared to individuals provided untreated diet. However, there was no effect on survival or body weight. Combinations of KCl + ouabain did not significantly affect caterpillar survival or body weight following treatment with 0.1 μg/μl bifenthrin. At the concentrations tested, there were no effects observed for bifenthrin sensitivity with increasing cardenolide or KCl concentrations. Further studies are warranted to understand how milkweed-specific cardenolides, at increasing concentrations, and agrochemical inputs can affect monarch caterpillar physiology near agricultural landscapes

Abundance and Diversity of Dung Beetles (Coleoptera: Scarabaeoidea) as Affected by Grazing Management in the Nebraska Sandhills Ecosystem

Dung beetles (Coleoptera: Scarabaeoidea) serve a significant role in regulating ecosystem services on rangelands. However, the influence of grazing management on dung beetle communities remains largely unknown. The purpose of this study was to investigate dung beetle abundance and diversity throughout the grazing season in the Nebraska Sandhills Ecoregion. Grazing treatments included: continuous grazing (CONT), low-stocking rotational grazing (LSR), high-stocking rotational grazing (HSR), and no grazing (NG). The abundance and diversity of dung beetles were measured in the 2014 and 2015 grazing seasons using dung-baited pitfall traps. Dung beetle abundance for each grazing treatment was characterized through four indices: peak abundance, species richness, Simpson’s diversity index, and Simpson’s evenness. A total of 4,192 dung beetles were collected through both years of trapping in this study. Peak abundance and species richness were greater in grazed treatments when compared to NG in both years. Peak abundance in the HSR was 200% (2014) and 120% (2015) higher than in the LSR. Species richness in the HSR was 70% (2014) and 61% (2015) higher than in the LSR, and 89% (2014) and 133% (2015) higher than in CONT. Simpson’s diversity index was lower in the NG and CONT treatments when compared to the LSR or HSR treatments for both years. We conclude that rotational grazing, regardless of stocking density, promoted dung beetle abundance and diversity within the Nebraska Sandhills Ecoregion