Dispar Japonica Research Articles

PCR-RFLP analysis of the ITS2 region to identify Japanese Lymantria species (Lepidoptera: Lymantriidae)

In this study, a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP)-based method for species identification was applied to eight Japanese Lymantria species, including the four “Asian gypsy moth” species [Lymantria dispar japonica (Motschulsky), Lymantria umbrosa (Butler), Lymantria albescens Hori and Umeno, and Lymantria postalba Inoue] and four other species [Lymantria xylina Swinhoe, Lymantria mathura Moore, Lymantria monacha (Linnaeus), and Lymantria lucescens (Butler)]. We sequenced the second internal transcribed spacer (ITS2) region of nuclear ribosomal DNA (rDNA) of one individual from each of the eight species. We analyzed the recognition sites of a restriction endonuclease (MnlI) to identify the Lymantria species by PCR-RFLP. We then applied PCR-RFLP analysis to 330 individuals from 54 populations of the 8 species. As a result, these species could be correctly identified with the exception of two species pairs (L. dispar japonica and L. umbrosa; L. albescens and L. postalba). These results suggest that this PCR-RFLP method based on the ITS2 region is useful for identifying Japanese Lymantria species.

Differences in Wing Morphometrics ofLymantria dispar(Lepidoptera: Erebidae) Between Populations That Vary in Female Flight Capability

All male gypsy moths, Lymantria dispar L., are capable of strong directed flight, but flight in females varies, increasing from west to east geographically across Eurasia. To better understand how the wings differ between female flight capable and flightless strains, a wing morphometric analysis of 821 gypsy moths from eight geographic strains (three Lymantria dispar dispar L., four Lymantria dispar asiatica Vnukovskij, one Lymantria dispar japonica Motschulsky) was performed. Body mass; length and width of both fore- and hindwing; and wing area, aspect, and loads were measured on both sexes from each strain. Gypsy moths were sexually dimorphic; females had a higher wing load, larger aspect ratios, bigger wing area, and heavier body mass than males. Wing loads of females, but not males, differed significantly among geographic strains and were lower in flight capable strains. Wing aspect was less variable within each sex among the strains. Female fore- and hindwing area were both larger in strains with strong directed flight capabilities compared with flightless strains, suggesting both fore- and hindwing areas play significant roles in flight. A logistic regression model using female forewing length and wing load correctly predicted the female flight capability of the source strains >97% of the time and may be a useful tool to use in conjunction with molecular methods for detecting introductions of Asian gypsy moth. None of the male morphometric wing characters were found to reliably predict the female flight capability of the source population.

日本産マイマイガ（チョウ目：ドクガ科）の性フェロモントラップ：ルアーの担持量，トラップ形状と誘殺数の関係

The effects of trap design on trap capture of two Japanese gypsy moth subspecies, Lymantria dispar japonica (Motchulsky) and L. d. hokkaidoensis Goldschmidt were tested in three locations (Bibai, Matsudo and Gifu). Among an USDA (United State Department of Agriculture) milk carton trap, a funnel trap and a sticky-type trap (SE-trap) baited with a rubber septum impregnated with 0.5 mg (+)-disparlure, SE-trap tended to capture the highest number of male moths. The effects of the amount of synthetic pheromone loaded onto a rubber septum were also tested in Sapporo and Matsudo. A rubber septum loaded with 0.5 or 5 mg of (+)-disparlure captured an equivalent number of male moths with an USDA polyvinyl chloride (PVC) lure in both places. These results suggest that a milk carton trap baited with a PVC lure may be replaced with a SE-trap baited with a rubber septum loaded with 0.5–5 mg (+)-disparlure to monitor the gypsy moth populations in Japan.

Mass Flights ofLymantria dispar japonicaandLymantria mathura(Erebidae: Lymantriinae) to Commercial Lighting, with Notes on Female Viability and Fecundity.1

Adult Lymantria dispar japonica (females only) and Lymantria mathura (both sexes) flew to commercial lighting during the night in Takizawa Village, Iwate Prefecture, Japan, in large numbers during the first week of August 2008. Males of L. d. japonica were conspicuously absent while 93.8% of responding females were mated and subsequently laid an average of 419.2 eggs each post-flight. For L. mathura females, only 33.9% were mated during the first half of the night and each mated female carried on average 717.4 eggs (max. 1065). Egg counts were facilitated by a newly developed egg mass matrix digestion process and an approximation of egg count based on egg mass dry weight was calculated. These two moth species have dissimilar behavioral strategies—L. d. japonica is diurnal, mated during the afternoon pre-flight and females flew to the lighting after mating. In contrast, L. mathura is nocturnal and both sexes responded to the lighting; females generally arrived as virgins (unfertilized) to then mate with males as the night progressed. Lack of a moth flight in 2009 illustrated dramatic interannual population fluctuation prevalent among many lymantriine moths. An illustration of a 2013 mass flight in Ono City, Fukui Prefecture, suggests a more frequent occurrence of such flights in both time and space.

Oviposition preferences of the Japanese Gypsy moth, <i>Lymantria dispar japonica</i> (Motschulsky, 1860) (Insecta: Lepidoptera: Erebidae: Lymantriinae), on evergreen broad-leafed tree leaves in Hiroshima Prefecture, Japan

2 Abstract: Female gypsy moths, Lymantria dispar dispar (Linnaeus, 1758), commonly deposit their egg masses on tree trunks in Europe and North America. However, in northern Japan (Hokkaido and northern Honshu) females of L. umbrosa (Butler, 1881) and L. dispar japonica (Motschulsky, 1860) show a strong preference for white birch, Betula platyphylla Sukatschev var. japonica (Miq.) Hara (Betulaceae), trunks. In those areas of Japan where white birches are absent, it has been unclear where most oviposition occurs. In southern part of Hiroshima Prefecture, southwestern Japan, where evergreen broad-leafed trees exist, a preliminary egg mass survey failed to find egg masses on any tree trunks. Subsequently an intensive survey of 1115 individual trees (of 36 different species) in three broad-leafed forest plots found 126 egg masses of which 125 (99.2%) were on Quercus glauca (Thunb.) (Fagaceae), Camellia japonica L. (Theaceae), Eurya japonica Thunb. (Theaceae), or Ilex purpurea Hassk (Aquifoliaceae), and 111 egg masses were positioned on the undersurface of new- growth Q. glauca leaves. In southern part of Hiroshima Prefecture, gypsy moth egg mass surveys in the future should focus on the evergreen leaves of broad-leaved trees, especially Q. glauca.

Male death resulting from hybridization between subspecies of the gypsy moth, Lymantria dispar.

We explored the origin of all-female broods resulting from male death in a Hokkaido population of Lymantria dispar through genetic crosses based on the earlier experiments done by Goldschmidt and by testing for the presence of endosymbionts that are known to cause male killing in some insect species. The mitochondrial DNA haplotypes of the all-female broods in Hokkaido were different from those of normal Hokkaido females and were the same as those widely distributed in Asia, including Tokyo (TK). Goldschmidt obtained all-female broods through backcrossing, that is, F1 females obtained by a cross between TK females (L. dispar japonica) and Hokkaido males (L. dispar praeterea) mated with Hokkaido males. He also obtained all-male broods by mating Hokkaido females with TK males. Goldschmidt inferred that female- and male-determining factors were weakest in the Hokkaido subspecies and stronger in the Honshu (TK) subspecies. According to his theory, the females of all-female broods mated with Honshu males should produce normal sex-ratio broods, whereas weaker Hokkaido sexes would be expected to disappear in F1 or F2 generations after crossing with the Honshu subspecies. We confirmed both of Goldschmidt's results: in the case of all-female broods mated with Honshu males, normal sex-ratio broods were produced, but we obtained only all-female broods in the Goldschmidt backcross and obtained an all-male brood in the F1 generation of a Hokkaido female crossed with a TK male. We found no endosymbionts in all-female broods by 4,'6-diamidino-2-phenylindole (DAPI) staining. Therefore, the all-female broods observed in L. dispar are caused by some incompatibilities between Honshu and Hokkaido subspecies.

Spacing of traps baited with species-specific Lymantria pheromones to prevent interference by antagonistic components

AbstractIn pheromone-based surveys for detecting multiple species of exotic lymantriine moths (Lepidoptera: Noctuidae: Lymantriinae), spacing between traps baited with species-specific pheromone lures must be sufficient to prevent antagonistic effects of heterospecific pheromone on lure attractiveness. Conducting field experiments with the Japanese gypsy moth, Lymantria dispar japonica Motschulsky, in northern Honshu, Japan, we first determined which congeneric pheromone components have strong antagonistic effects on attraction of male moths to the conspecific pheromone (7R,8S)-cis-7,8-epoxy-2-methyloctadecane ((+)-disparlure). Since the most antagonistic compounds were pheromone/volatile components from the sympatric nun moth, L. monacha (L.), we then conducted experiments with paired traps baited with either a L. dispar (L.) pheromone lure ((+)-disparlure (50 µg)) or L. monacha pheromone lure (a mixture of (7R,8S)-cis-7,8-epoxyoctadecane ((+)-monachalure (50 µg)), (7Z)-2-methyloctadecene (5 µg), and (+)-disparlure (50 µg)). As spacing between paired traps increased (0, 0.5, 2, 7.5, 15, or 30 m), the antagonistic effect of the L. monacha lure on the attractiveness of the L. dispar lure decreased and finally disappeared. For pheromone-based detection surveys of multiple species of exotic lymantriine moths in North America to be effective, trap spacing of 15 m is recommended.

Termination of diapause in pharate first-instar larvae of the gypsy moth Lymantria dispar japonica by an imidazole derivative KK-42

1-Benzyl-5-[( E)-2,6-dimethyl-1,5-heptadienyl] imidazole (KK-42) terminated diapause in pharate first-instar larvae of the gypsy moth, Lymantria dispar japonica. This effect of KK-42 was not prevented with juvenile hormone III and its analogs (methoprene and S-31183). In addition, free ecdysteroid titers were lower in diapausing eggs and the eggs treated with KK-42. These results indicate that KK-42 has the same function as in the breakdown of diapause of pharate first-instar larvae in the wild silkmoth, Antheraea yamamai.

Betula platyphylla : 1 the Preferred Oviposition Host of Lymantria dispar japonica 2 in Hokkaido, Japans

Japanese gypsy moth, Lymantria dispar japonica Motschulsky, in low population densities in northern Japan's mixed species forests, oviposited almost exclusively on the white bark of Betula platyphylla Sukatschev: in plots totaling 3.3 ha, 88 of 90 egg masses were on white birches, which comprised < 30% of the stand composition. Likewise, high densities of the moth in a planting of Larix leptolepis (Sieb. and Zucc.) Gord. preferred to oviposit on B. platyphylla: 3 white birches among 154 trees (0.09 ha) held 84% of the egg masses, and one birch that had a DBH of 17 cm held 482 masses. These findings have practical application for field workers who wish to collect gypsy moth eggs in northern Japan where white birch is found.

Mixed Infection of the Gypsy Moth, Lymantria dispar japonica MOTSCHULSKY (Lepidoptera : Lymantriidae), in a Larch Forest by Entomophthora aulicae (REICH.) SOROK. and Paecilomyces canadensis (VUILL.) BROWN et SMITH

Field observations of an epizootic in gypsy moth (Lymantria dispar japonica MOTSCHULSKY) population by two pathogenic fungi during the summer of 1972 in a larch forest in Tohoku District of Japan indicated that fungus-killed larvae occurred in about 99% of the population. Mixed infection of Paecilomyces canadensis (VUILL.) BROWN et SMITH and Entomophthora aulicae (REICH.) SOROK. occurred in about 20% of the dead larvae, which showed typical muscardine. Only E. aulicae was found in the remaining fungus-killed larvae. Most of the dead larvae were found near the base of the tree trunks.