No abstract

The mating behavior of the male Gastrophysa atrocyanea, that is, extrusion of the aedeagus, was elicited by the cuticular hydrocarbons on the surface of the female body. Males attempted to mate with a dummy treated with the female equivalent of the female elytra extracts. After fractionation of the elytra extracts by Florisil column chromatography and reverse phase high performance liquid chromatography, two fractions, consisting mainly of methylheptacosanes and methylnonacosanes were found to elicit the male mating behavior. These compounds, synthetic 9-methylheptacosane, 11-methylheptacosane, 9-methylnonacosane and 11-methylnonacosane, were contained in active fractions and showed high pheromonal activity. Therefore, these monomethylalkanes were considered to be contact sex pheromones of this beetle. However, synthetic 13-methylheptacosane, 13-methylnonacosane and 15-methylnonacosane, positional isomers of active monomethylalkanes, also contained in the active fractions, did not have the activity. A mixture of these seven monomethylalkanes at approximately natural concentrations also had enough activity to elicit the male mating behavior. Furthermore, the results of a bioassay using some related structural monomethylalkanes revealed that the length of the carbon backbone and the position of the methyl branch greatly influenced the pheromonal activity of G. atrocyanea.

Adult secretions of four Japanese Chrysomelinae, Gastrophysa atrocyanea, Plagiodera versicolora distincta, Chrysomela vigintipunctata costella, and Gastrolina depressa (Coleoptera: Chrysomelidae) were analyzed by TLC, HPLC, NMR and FAB-MS. Three nitropropanoyl isoxazolinone glucosides, 2- (4) were found in all species. In addition, two nitropropanoyl glucosides, 1,6-di-(3Ј-nitropropanoyl)-b-D-glucopyranose (2) and 1,2,6-tri-(3Ј-nitropropanoyl)-b-Dglucopyranose (5) were also detected from these species. The secretions of the four species and compounds 3 and 5 showed strong deterrent effects against ants (Tetramorium caespitum), whereas compounds 2 and 4 exhibited low activity.

To clarify the reproductive properties of the coconut palm pest, Brontispa longissima (Gestro) (Coleoptera: Chrysomelidae), we investigated in the laboratory the diel periodicity in copulation, effect of adult age after emergence on copulation and ovarian development, reproductive development in relation to female age, and the possibility of multiple mating. The beetles used in this study were reared in the laboratory and were fed an alternative food plant, narrowleaf cattail, Typha domingensis Pers. (Typhaceae). Copulation occurred throughout the 24-h cycle but mostly occurred in the photophase with two peaks, one at the onset of lights-on and the other 8–12 h after lights-on, indicating that most copulation activity in B. longissima in the field occurs in the early morning and the afternoon. Females could copulate immediately after emergence, whereas males began copulating 3 wk after emergence. Ovaries of females started to develop in the absence of mating and were correlated with adult age. Mature males could copulate with females regardless of ovarian developmental stage, and females with undeveloped ovaries accepted copulation attempts. Our study showed that the timing of copulation during the preoviposition period would not affect numbers of eggs laid, length of preoviposition period, or viability of eggs. B. longissima adults engaged in multiple mating.

Three components, hexyl butyrate (ϭbutanoate) (6:nBu), (E)-4-oxohex-2-enal (E2O4-6:Ald) and (E)-hex-2-en-1-yl butyrate (E2-6:nBu), were identified as sex attractant pheromone components of the sorghum plant bug Stenotus rubrovittatus (Matsumura) (Heteroptera: Miridae) in a previous study. The optimum ratio and amount of the three components loaded into rubber septa for male attraction were investigated. A 5:10:1 blend of 6:nBu, E2O4-6:Ald and E2-6:nBu at 64 mg per rubber septum was most effective for male attraction and regarded as an 'optimized blend'. The attractiveness of the optimized blend lures did not differ between lures with and without a sunshade and was equal to that of 10 unmated females. The attractiveness of optimized blend lures after weathering for 14 d did not differ from fresh lures, whereas the attractiveness of optimized blend lures weathered for more than 21 d was lower than fresh lures. Female extracts of S. rubrovittatus contain 13 minor components; however, the attractiveness of lures impregnated with female extracts did not differ from optimized blend lures. This result suggests that minor components at the amounts contained in the female extract do not strongly enhance its attractiveness.