Electroantennogram Responses of the Armyworm (Lepidoptera: Noctuidae) and Cereal Leaf Beetle (Coleoptera: Chrysomelidae) to Volatile Chemicals of Seedling Oats

Armyworm, Pseudaletia unipuncta, eIectroantennogram (EAG) responses to 10 volatile chemicals of seedling oats and three of injured green plants were significantly different from each other while cereal leaf beetle, Oulema melallopus, EAG responses were not significantly different. The EAG responses of both species did not vary significantly with respect to sex, age, or between the antennae of the same specimen. (E)-2-hexenol, a compound extracted from injured green plants, yielded the highest peak response for the armyworm while more cereal leaf beetle antennae responded to this chemical than any other chemical. Armyworm antennallife averaged 38 + 20 min while those of the cereal leaf beetle averaged 6 + 14 min

Pupal and Adult Parameters as Potential Indicators of Cottonwood Leaf Beetle (Coleoptera: Chrysomelidae) Fecundity and Longevity

Cottonwood leaf beetle, Chrysomela scripta, pupae from a laboratory colony were weighed and monitored through adult emergence, oviposition, and mortality to determine if correlations existed between various pupal or adult parameters and fecundity or longevity. Forty-three female cottonwood leaf beetles were monitored. Pupal weight was not a good indicator of fecundity, total oviposition events, number of eggs/beetle/day, or adult longevity. In addition, adult weight showed very low correlation with fecundity, adult longevity, total oviposition events, or number of eggs/beetle/day. However, adult weight was a marginal indicator of the number of eggs/beetle/day, and correlated well with adult body length. Adult longevity could be used to predict fecundity

Cross-Resistance and Resistance Longevity as Induced by Bean Leaf Beetle, Cerotoma trifurcata and Soybean Looper, Pseudoplusia includens herbivory on Soybean

Cross-resistance, and longevity of resistance, induced by the bean leaf beetle, Cerotoma trifurcata, was studied IN the soybean PI 227687 that exhibited induced response in earlier studies. Bean leaf beetle adults and soybean looper, Pseudoplusia includens, larvae were used to induce resistance and to determine beetle feeding preference. Beetles were collected from soybean fields 2 to 5 days prior to the feeding preference test. The level of cross-resistance induced by soybean looper herbivory to subsequent bean leaf beetle feeding was higher when compared to cross-resistance induced by bean leaf beetle herbivory against subsequent feeding by soybean looper. Further, herbivory by the bean leaf beetle also induced resistance against soybean looper feeding. In the longevity study, leaflets from treated plants were collected 5, 10, 12, 14, 16, 20 and 25 days after initiation of feeding. Pairwise comparisons of leaflets from plants treated by bean leaf beetle herbivory with untreated plants revealed that induced responses were highest 14 and lowest 25 days after initiation of feeding. On other sampling days, levels of induced response varied with the sampling day

Damage Potential of Rose Chafer and Japanese Beetle (Coleoptera: Scarabaeidae) in Michigan Vineyards

Responses of young non-fruiting grapevines, Vitis labrusca (L.) var. ‘Niagara’, to defoliation were examined at two stages of vine growth when beetles typically infest vineyards. In the first experiment, vines were caged and subjected to two weeks of feeding by 0, 10, 20, or 40 adult Macrodactylus subspinosus Fabricius (Scarabaeidae: Macrodactylini) during bloom, or to the same range of adult Popillia japonica Newman (Scarabaeidae: Anomalini) during veráison, when berries begin changing color. Leaf area removed increased with beetle density, but less than 1% of the leaf area was removed at the highest density of M. subspinosus, and less than 7% at the highest density of P. japonica. Vine growth measurements taken during the year of injury and prior to bloom during the following season indicated no significant impacts of this leaf injury on vegetative growth. In the second experiment, mechanical injury was induced by removing 0, 10, 20, or 30% of the total leaf area of every fully expanded leaf at bloom or veráison. A significant effect of mechanical injury at bloom was found on cane diameters when measured at veráison, indicating that a carbon source limitation was induced in these vines. By the time of leaf loss, cane diameters were not significantly different across treatments, indicating that vines may have been able to compensate for the earlier defoliation. Injury at veráison had no significant effect on vine growth parameters. These results suggest that young ‘Niagara’ vines are able to tolerate foliar injury far exceeding that caused by two weeks of exposure to 40 beetles of either species. Surveys of Michigan vineyards containing different grape varieties indicated that although both beetle species could be found in high abundance, leaf injury levels were low. The implications for management of beetle foliar herbivory in vineyards are discussed

Management of bean leaf beetle to reduce defoliation

The last three issues of the ICM newsletter have contained articles on the bean leaf beetle in soybean. The April 29 article reported high winter survival of the beetles; the May 6 article outlined the early-season management of the beetle and bean pod mottle virus; and the May 20 article showed how to distinguish between twelvespotted lady beetle and bean leaf beetle. My article adds to the saga by discussing beetle management to reduce defoliation

Cereal Leaf Beetle (Coleoptera: Chrysomelidae) and Winter Wheat: Host Plant Resistance Relationships

The cereal leaf beetle was introduced into North America from Europe prior to 1960. An overview of the control of the insect in North America is presented with major emphasis on host plant resistance. The length and density of the adaxial trichomes (pubescence or leaf hairs) convey resistance to wheat, and the amount of resistance can be estimated mathematically without the insect being present