Our objective was to test the hypothesis that the pheromone blend and/or diel periodicity of pheromonal communication differ in populations of the nun moth, Lymantria monacha (Lepidoptera: Lymantriidae), from eastern Asia (northern Honshu, Japan) and Central Europe (Bohemia, Czech Republic). Coupled gas chromatographic-electroantennographic detection (GC-EAD) analyses of pheromone gland extract of female L. monacha from Japan confirmed the presence of compounds previously identified in pheromone extracts of L. monacha from Bohemia, as follows: (Z)-7-octadecene, 2-methyl-(Z)-7-octadecene (2me-Z7-18Hy), cis-7,8-epoxy-octadecane (monachalure), and cis-7,8-epoxy-2-methyloctadecane (disparlure). Field experiments in Honshu suggested that (+)-monachalure is the major pheromone component of L. monacha. 2me-Z7-18Hy significantly enhanced attractiveness of (+)-monachalure. Addition of (+)-disparlure to (+)-monachalure plus 2me-Z7-18Hy in Honshu and Bohemia increased attractiveness of lures by 1.2 and 20 times, respectively, indicating that (+)-disparlure is of least and most significance in the respective L. monacha populations. Moreover, capture of male L. monacha in pheromone-baited traps between 18:00 and 24:00 hr in Bohemia and 2:00 and 5:00 hr in Honshu revealed a markedly different diel periodicity of pheromonal communication. Pheromonal communication late at night and use of (+)-monachalure, rather than (+)-disparlure, as the major pheromone component by L. monacha in Honshu may have resulted from interspecific competition with coseasonal L. fumida, which uses the early night for pheromonal communication and (+)-disparlure as major pheromone component. Whether communication channel divergence of L. monacha in Honshu indeed constitutes a case of reproductive character displacement is difficult to prove. The evolution of such divergence in sympatric populations of L. fumida and L. monacha would have to be demonstrated.

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The mating behavior of the sciarid fly, Lycoriella mali, a serious insect pest of mushroom cultivation in Japan, was analyzed for the presence of sex pheromones. Unmated male flies made copulatory responses, such as wing fanning, ventral bending of abdomen and opening of clasper, to an unmated female, crude extracts of an unmated female and separate body parts of an unmated female, suggesting the presence of female sex pheromones on all parts of female flies. However, unmated male flies did not make any copulatory responses to 10-4 to 10-11g of n-heptadecane, previously reported as a sex pheromone of the flies in the USA. Unmated females elicited copulatory responses from males when older than 2h after adult eclosion. Unmated males made copulatory responses to unmated females when older than 1h after adult eclosion. Unmated females elicited copulatory responses by males until 3 days after adult eclosion. On the other hand, 100% of unmated males showed copulatory responses even at 9 days after adult eclosion. The copulatory responses of unmated males to mated females decreased quickly after the female had mated once.

Infestations by stem borers in teak (Tectona grandis) and yemane (Gmelina arborea) plantations were surveyed at seven locations in Sabah, Malaysia in March, 1998. The teak beehole borer (Xyleutes ceramica) and the collar ring borer (Endoclita aroura) were found to attack teak and yemane. X. ceramica accounted for most of the boring attacks in teak plantations, damaging 10.3-65.2% of the planted trees, except at one location where no stem borer attack was detected. The number of past and present attacks per tree ranged from 0.27-1.28 and 0.01-0.62, respectively. In contrast, E. aroura was of minor importance, attacking 6.9% or less of the planted trees. Analysis of spatial distribution of past attacks by the teak beehole borer in young teak stands revealed a contagious pattern. The past attacks were heavier on bigger trees. Both past and present attacks were concentrated in the lower part of the trunk, less than 1 m from the ground level. In young stands of yemane, an unidentified lamiine cerambycid damaged 0.0-14.1% of the trees, whereas the teak beehole borer damaged 7.6-12.2% of the trees.

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