Populations of the gall midge Dasineura oxycoccana on cranberry and blueberry produce and respond to different sex pheromones.

We identified and field-tested the sex pheromones of Dasineura oxycoccana (Johnson) (Diptera: Cecidomyiidae) midges collected from cranberry, Vaccinium macrocarpon Aiton, and from highbush blueberry, Vaccinium corymbosum L., commonly named cranberry tipworm (CTW) and blueberry gall midge (BGM), respectively. Coupled gas chromatographic-electroantennographic detection (GC-EAD) analyses of pheromone gland extract from the ovipositor of calling CTW females revealed one component (<10 pg per ovipositor/pheromone gland) that elicited antennal responses from CTW males. Stepwise identification was based on its mass spectrum in a concentrated sample with 300 pheromone gland equivalents, retention indices (RI) on three GC columns (DB-5, DB-23, and DB 210), RI inter-column differentials, and RIs and double bond positions of other midge pheromones. These analyses indicated that (8Z)-2,14-diacetoxy-8-heptadecene (2,14-8Z-17) was the candidate pheromone of the CTW. GC-EAD analysis of pheromone gland extract from calling BGM females revealed two components that elicited antennal responses from BGM males. Retention times on the three GC columns were consistent with 2,14-8Z-17 and 2,14-17, indicating that these were candidate pheromone components of the BGM. The four stereoisomers of 2,14-8Z-17 were stereoselectively synthesized and field-tested in cranberry. Delta-type traps baited with SS-2,14-8Z-17 captured significantly more CTW males than did traps baited with any other single stereoisomer or with all four stereoisomers combined. In blueberry, delta-type traps baited with RR-2,14-8Z-17 captured significantly more BGM males than did traps baited with any other single stereoisomer or with all four stereoisomers combined. Subsequent field experiments demonstrated that RR-2,14-17 is the major pheromone component of BGM, and that RR-2,14-8Z-17 is a pheromone component that does not enhance attractiveness of RR-2,14-17. The BGM pheromone RR-2,14-17 has no antagonistic effect on the CTW pheromone SS-2,14-8Z-17 and vice versa. Our results substantiate the conclusion that populations of D. oxycoccana on cranberry and blueberry represent two cryptic species.

Phenology of Dasineura oxycoccana (Diptera: Cecidomyiidae) on cranberry and blueberry indicates potential for gene flow.

Dasineura oxycoccana (Johnson) (Diptera: Cecidomyiidae) is a pest of cranberry, Vaccinium macrocarpon (Aiton) (Ericales: Ericaceae), and highbush blueberry, Vaccinium corymbosum (L.) (Ericales: Ericaceae), in North America. In British Columbia, Canada, D. oxycoccana was first found on highbush blueberry in 1991 and then on cranberry seven years later. Because many cranberry and highbush blueberry farms are adjacent to one another, we hypothesized that D. oxycoccana was moving from highbush blueberry onto cranberry. Cranberry and highbush blueberry differ in phenology, and adaptation to these different phenologies may result in host races or cryptic species on these two crops. We recognized the alternative hypothesis that D. oxycoccana had arrived as immature stages with cranberry vines imported from another region of North America. During spring and summer, we recorded the phenology of D. oxycoccana and the development of plant shoots from three cranberry and three highbush blueberry farms to determine whether the opportunity exists for successful movement of D. oxycoccana between the two crops. Our results show that D. oxycoccana from cranberry and highbush blueberry overlap in phenology for much of the season, indicating a high potential for movement and gene flow. However, differences were seen in number of larvae per shoot, location of pupae, and heat unit accumulation during larval development suggesting that instead there may be the potential for host race or cryptic species formation.

Trapping Phyllophaga spp. (Coleoptera: Scarabaeidae: Melolonthinae) in the United States and Canada using sex attractants.

The sex pheromone of the scarab beetle, Phyllophaga anxia, is a blend of the methyl esters of two amino acids, L-valine and L-isoleucine. A field trapping study was conducted, deploying different blends of the two compounds at 59 locations in the United States and Canada. More than 57,000 males of 61 Phyllophaga species (Coleoptera: Scarabaeidae: Melolonthinae) were captured and identified. Three major findings included: (1) widespread use of the two compounds [of the 147 Phyllophaga (sensu stricto) species found in the United States and Canada, males of nearly 40% were captured]; (2) in most species intraspecific male response to the pheromone blends was stable between years and over geography; and (3) an unusual pheromone polymorphism was described from P. anxia. Populations at some locations were captured with L-valine methyl ester alone, whereas populations at other locations were captured with L-isoleucine methyl ester alone. At additional locations, the L-valine methyl ester-responding populations and the L-isoleucine methyl ester-responding populations were both present, producing a bimodal capture curve. In southeastern Massachusetts and in Rhode Island, in the United States, P. anxia males were captured with blends of L-valine methyl ester and L-isoleucine methyl ester.