Antennal response and field attraction of the predator Elatophilus hebraicus (Hemiptera: Anthocoridae) to sex pheromones and analogues of three Matsucoccus spp. (Homoptera: Matsucoccidae).

The predator Elatophilus hebraicus is closely associated with its prey, the pine bast scale, Matsucoccus josephi, and utilizes the M. josephi sex pheromone as a kairomone. Kairomonal activity of E. hebraicus was studied by GC-EAD and field bioassays. The sex pheromone of M. josephi [2E,5R,6E,8E)-5,7-dimethyl-2,6,8-decatrien-4-one [(R)-E-M.j.] elicited a strong EAD response and attracted large numbers of the predator. The sex pheromone of two allopatric Matsucoccus spp., Matsucoccus feytaudi, (3S,7R,8E,10E)-3,7,9-trimethyl-8,10-dodecadien-6-one [(S,R)-E-M.f.] and Matcucossus matsumurae, (2E, 4E,6R,10R)-4,6,10,12-tetramethyl-2,4-tridecadien-7-one [(R,R)-E-M.m.], were also EAD-active and attracted significant numbers of E. hebraicus in the forest. Increasing the lure load of (S,R)-E-M.f. and (R,R)-E-M.m., in order to compensate for their lower volatility relative to (R)-E-M.j., resulted in similar attraction of E. hebraicus to each of the three pheromones. Other Matsucoccus pheromone stereoisomers displayed no behavioral activity. There was a significant difference in the activity of sex pheromone analogues, (6E/Z,8E)-5,7-dimethyl-6,8-decadien-4-one (52% E + 48% Z, ANLG 1) and (6E/Z,8E)-2,4,6-trimethyl- 1,6,8-nonatrien-3-one (60% E + 40% Z, ANLG 2). The (E) isomer of ANLG 1 evoked a strong EAD response from E. hebraicus and the mixture of E/Z ANLG 1 attracted the predator in moderate numbers, whereas ANLG 2 was inactive both in EAD and field tests. Conversely, M. josephi males were not attracted to M. feytaudi and M. matsumurae pheromones or pheromone analogues. Cross-activity of E. hebraicus to M. feytaudi and M. matsumurae pheromones may be based on structural similarity of the compounds. Alternatively, E. hebraicus may respond specifically to the pheromones of two allopatric Matsucoccus spp. If true, kairomonal attraction of E. hebraicus to these pheromones may have evolved during speciation of Matsucoccidae and may have been preserved despite the allopatry of M. josephi, M feytaudi and matsumurae.