Dogwood borer (Lepidoptera: Sesiidae) abundance and seasonal flight activity in apple orchards, urban landscapes, and woodlands in five eastern states

Sex pheromone of the smaller clearwing moth Synanthedon tenuis (Butler)

The smaller clearwing moth, Synanthedon tenuis (Butler) (Lepidoptera: Sesiidae), is a major pest of persimmon in northeast Asia. A previous study reported attraction of S. tenuis males to Z3,Z13-18:OAc, but this compound had no effect on male catch in the persimmon orchards in Korea. In this study, we analyzed pheromone gland extracts of S. tenuis females and identified Z3,Z13-18:OH as the main component. In field trapping trial, Z3,Z13-18:OH alone was attractive to S. tenuis males and competitive with live virgin females. These results indicate that the pheromone of this species consists of a single component, Z3,Z13-18:OH. However, Z3,Z13-18:OAc, a previously reported attractant, was not detected in the gland extracts of females. Furthermore, the addition of Z3,Z13-18:OAc to the main pheromone component strongly inhibited attraction for males, suggesting that the diene acetate is not a pheromone component. This is the first report of an octadecadienol as female-produced sex pheromone from the genus Synanthedon.

Postmating behavior of female dogwood borer (Lepidoptera: Sesiidae) in apple orchards

The postmating behavior of female dogwood borer, Synanthedon scitula (Harris) (Lepidoptera: Sesiidae), was examined in a young apple orchard planted on size-controlling rootstock in Virginia. All female dogwood borers captured while exhibiting casting flight near the base of trees were mated, based on the presence of a spermatophore. Surveys of female activity within orchards were conducted at regular intervals throughout the daylight hours, showing a diel periodicity that peaked between 1700 and 1900 hours, with most females located below the graft union of trees. A transition matrix based on 1,108 behavioral sequences exhibited by 66 females was used to produce a first-order Markov chain of behavioral events that occurred significantly more often than expected by chance. Casting flight, probing with ovipositor, and oviposition were the most frequent behaviors observed, representing 31.7, 30.0, and 18.1% of all behaviors recorded, respectively. Our observations showed that 88, 99, and 99% of casting flight, probing with the ovipositor, and oviposition, respectively, occurred below the graft union. Observed behaviors considered not directly related to oviposition site selection or oviposition included antennal grooming, noncasting flight, and resting, representing 1.3, 8.3, and 10.6% of all behaviors recorded, respectively. Mated females spent significantly more time resting than in other behaviors and significantly more time in that state within the apple tree canopy than on other parts of the tree. Results are discussed in relation to the influence of insect-host plant interactions on oviposition site selection by female dogwood borer.