Botanical Volatiles Selection in Mediating Electrophysiological Responses and Reproductive Behaviors for the Fall Webworm Moth Hyphantria cunea.

Host-plant volatiles play vital roles for insects to locate foraging, mating, and oviposition sites in the environment. As one of the devastating invasive forestry pests, Hyphantria cunea causes a great annual loss in China, and understanding its chemical ecology is an important task. The current research was done in terms of chemical analysis, electrophysiology, and behavioral assays on H. cunea to assess its olfactory reception toward host-plant volatiles. A screen of possible common host volatiles was done, targeting on five favored hosts of H. cunea, harvesting six potential bioactive compounds from a total of 78 odorant components. Six types of antennal sensilla were investigated on their distributions on the antennae, and sexual dimorphism was described. H. cunea showed responses to all selected host-related volatiles in electroantennogram tests, and linalyl butyrate elicited the strongest responses. Furthermore, mating rates in adult pairs that are exposed to dibutyl phthalate and phytol have been significantly increased, while oviposition rates and female fecundity were not influenced. The results of the current study provide initial evidence showing that universal host-derived volatile cues are essential for H. cunea moth in terms of mating, which can also provide insights into the development of botanical attractants.

A Comparison of Novel Entomopathogenic Nematode Application Methods for Control of the Chive Gnat, Bradysia odoriphaga (Diptera: Sciaridae).

Bradysia odoriphaga Yang & Zhang (Diptera: Sciaridae) is the most serious pest of Chinese chive, Allium tuberosum Chemical pesticide application has become a necessary step to control B. odoriphaga after each of the four to six harvests during the growing season. We compared the effects of application type (nematode-infected cadaver, aqueous nematode suspension, and mixture of cadaver and aqueous suspension) and nematode species (Heterorhabditis bacteriophora vs. Steinernema carpocapsae) on B. odoriphaga control. Nematode species combinations and the use of the cadaver method has only been tested in a relatively few studies, and has not been tested for this target pest, B. odoriphaga. Furthermore, this is the first report of combining application methods (aqueous and cadaver). Results indicated that the cadaver treatment produced higher mortality of B. odoriphaga than the aqueous treatment, and H. bacteriophora caused higher mortality of B. odoriphaga than S. carpocapsae. The mortality of B. odoriphaga was 96.7% in H. bacteriophora cadaver treatment and only 27.5% in control treatment without nematode addition. Cadaver treatments caused higher biomass of A. tuberosum than that of aqueous treatment. The plant biomass in H. bacteriophora cadaver treatment was 10 folds as much as that in the control treatment. The mixed aqueous suspension of H. bacteriophora and S. carpocapsae did not increase the mortality in pot trial. Our findings indicate that entomopathogenic nematodes applied as cadavers might be a potential alternative biological agent in the integrated management of B. odoriphaga for Chinese chive production.