小木原湿地（山口県萩市）におけるエゾスズPteronemobius yezoensis Shiraki （Orthoptera: Trigonidiidae）の生活史（2）翅型・幼虫期間・羽化率・体サイズに対する光周期の影響

Life cycle of Pteronemobius yezoensis Shiraki (Orthoptera: Trigonidiidae) in Kogihara wetland, Hagi City, Yamaguchi Prefecture (2) Effects of photoperiod on wing form, nymphal development, percentage of adult emergence, and body size

Creators ARAI Tetsuo

Creators Akagi Koichi

Creators Furubayashi Aya

Adult of Pteronemobius yezoensis (Shiraki, 1913) (Orthoptera: Trigonidiidae) were collected from the Kogihara wetlands in Hagi City (formally Asahi-son, Abu-gun), Yamaguchi Prefecture (32.2° N, 131.5° E, approximately 400m above sea level). Eggs were collected in the laboratory of Yamaguchi Prefectural University.Nymphs that hatched within 24 h were reared under photoperiods from 10 h-light and 14 h-dark photoperiod (LD 10:14) to LD 18:6 at 28.0 ± 1.0ºC and the wing form, nymphal development, percentage of adult eclosion, and body size were investigated.The macropterous form rarely appeared under photoperiods from LD 10:14 to LD 14:10, but increased rapidly with those longer than LD 15:9 and was more than 50% at LD 16:8. For all photoperiod treatments, the percentage of macropterous form in females was higher than that in males.In the micropterous form, the nymphal development under photoperiods from LD 10:14 to LD 15:9 was 100 days or more in both males and females, but it was approximately 80 days under photoperiods of LD 16:8 and LD 18:6. The macropterous form was approximately 60 days under photoperiods from LD 15:9 to LD 18:6. The nymphal development of the macropterous form was shorter than that of the micropterous form in both males and females. In any photoperiod, the nymphal development of both wing forms tended to be longer in females than in males.The percentage of adult eclosion was 25% or less, 55%, and 75% or more under photoperiods from LD 10:14 to LD 14:10, LD 15:9, and LD 16:8, respectively. The number of dead individuals under photoperiods from LD 10:14 to LD 13:11 increased early after hatching and gradually increased over the entire period under LD 14:10. The number of dead individuals increased gradually under photoperiods from LD 15:9 to LD 18:6. In any photoperiod, a small number of individuals survived more than 160 days after hatching. All nymphs died without emergence under hotoperiods from LD 10:14 to LD 14:10, but most of them emerged under photoperiods from LD 15:9 to LD 18:6.Both the head width and hind leg femur length of the micropterous form were longer than those of the macropterous form in both males and females. Overall, they were longer in females than in males for both wing forms. The front wing length of the macropterous form was longer than that of the micropterous form in both males and females. The head width and hind leg femur length under LD 15:9−LD 18:6 of the micropterous form were longer than those under LD 10:14−LD 12:12 in both males and females. There was no clear tendency for the effects of photoperiods on the lengths of the hind wings and ovipositors.

[ISSN]2189-4825