|POLAVARAPU, SRIDHAR - RUTGERS UNIVERSITY
Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2004
Publication Date: 7/1/2004
Citation: Zhang, A., Polavarapu, S. 2004. Sex pheromone of the blueberry leafminer, Caloptilia porphyretica. Journal of Chemical Ecology. 30(7):1513-1527.
Interpretive Summary: The blueberry leafminer has become a regular occurrence in commercial high-bush blueberries grown in Atlantic and Burlington Counties of New Jersey. Severe infestations, as high as 40-50 % leaves with mines, have been observed in many locations in New Jersey. Although blueberry bushes can tolerate leaf mining to some extent without loss of production, severe infestations may affect the general vigor and cause yield loss. In addition to direct production loss, this insect can become a contaminant, especially in machine-harvested fruit, as the larvae drop from bushes along with harvested fruit. The presence of larvae in harvested fruit can substantially increase sorting time on the packing lines and may result in a contaminated product. At present, little is known of biology and seasonal life history of C. porphyretica. Using the gas chromatographic-electroantennographic detection technique, we determined that female blueberry leafminer release a single compound as the sex attractant. The field tests demonstrated that traps baited with the chemical were attractive to males, and adult flight activity occurred during three distinct periods per season. Traps baited with this lure can provide information on population levels, thereby helping growers apply insecticide in a timely manner. Furthermore, the identification of the sex attractant will also enable future development of mating disruption and attract-and-kill technologies for managing blueberry leafminer populations.
Technical Abstract: Coupled gas chromatographic-electroantennographic detection (GC-EAD) of both gland extracts and effluvial collections from female blueberry leafminer, Caloptilia porphyretica Braun (Lepidoptera: Gracillariidae), showed that the females produced a single EAD active compound. The amount of natural pheromone collected from virgin female C. porphyretica was below the GC-flame ionization detector (FID) and mass spectrometry (MS) detection thresholds, even with highly concentrated gland extracts (~150 female equivalent). (E)-11-Hexadecenal (E11-16:Al) was identified as the pheromone component by comparison of EAD-active compounds' peak retention times with authentic standards on both polar and non-polar capillary columns and micro-reaction-GC-EAD analyses. The GC-EAD experiments proved that synthetic E11-16:Al exhibited extraordinary high electrophysiological activity, resulting in significant male antennal responses at as low as the 10 femto-gram (10-12) level. Field tests demonstrated that traps baited with E11-16:Al alone were attractive to males. Addition of 1 or 3 percent of its geometric isomer, Z11-16:Al, to E11-16:Al did not significantly increase trap captures compared to E11-16:Al alone, but significant inhibitory effect was observed at the 10 percent level. The influence of two kinds of rubber septa on trapping efficiency was also evaluated in two separate field tests. Data from these studies indicated that male moth captures, except at the lowest (3-'g) and the highest (1000-'g) doses tested, were significantly greater in traps baited with red natural rubber septa compared to gray halo-butyl rubber septa at 30-300-'g loading. Monitoring of adult flight activity with 3-'g dose of E11-16:Al indicated three distinct flight periods throughout the 2003 season.