Yasumasa KUWAHARA. Noki MORI
Pesticide Research Institute, Faculty of Agriculture, Kyoto University,
Sakyo-ku, Kyoto 606-01, Japan
The female sex pheromones (produced by females and functioning as the specific male's sexual excitant) have been identified in following four species of genus Caloglyphus, including two unidentified; sp. 1, C. polyphyllae, C. rodriguezi and sp. 2, as (2R, 3R)-epoxyneral [2R,3R-epoxy-3,7-dimethyl-6-octenal], ß-acaridial [2(E)-(4-methyl-3-pentenylidene)-butandial], undecane and rosefuran [2-(3-methyl-2-butenyl), 3-methyl-frhan], respectively. These compounds were, however, commonly distributed not only in females, but also in con-specific males and, in extreme cases, also detectable in nymphal stages.
In order to understand those phenomena rationally, content of each pheromone was determined among both sexes and developmental stages. Frequencies of sexual behavior during a given period and lag-times before starting sexual behavior were compared between set-ups of male-male and of male-female confrontation.
Content ratio of female to male varied from 1.4 (sp. 1), 3.4 (C. polyphyllae), 6.3 (C. rodriguezi) to 8.4 (sp. 2). In nymphal stages of the sp. 1 and C. polyphyllae, their pheromone were detectable as a major component, while trace amount in the other two species. Evaluation of male's ability for recognizing nonspecific females revealed that males of all three species except the sp. 1 could discriminate between females and males.
As a result, the mite sex pheromone was suggested to have evolved from a common compound, present in the opisthonotal gland and functioning as male's sexual excitant, into the sex linked specific one with biological activity.