Biological research on beach cricket, Taiwanemobius formosanus Yang et Chang (Orthoptera: Nemobiidae)

• Main Authors: Chih-Chieh Huang, 黃致玠
• Other Authors: 楊正澤
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/17624003018704599504

碩士 === 國立中興大學 === 昆蟲學系所 === 97 === Taiwan beach cricket(Taiwanemobius formosanus Yang et Chang, 1996) was described by Jeng-Tze Yang and Yu-Lin Chang in 1996. The preliminary research indicates that Taiwan beach cricket lives in pebble sandy beach in the eastern coast of Taiwan, including off-shore Lanyu Island. But in the past ten years, no one study again on their basic biology. The whole study began at acquired the references of the biology of beach crickets, such as food habit, life history, distribution, circadian, reproductive behavior and so on. Then the study moved into field investigation and laboratory experiment. Investigating on the information of spatial distribution, habitat, circadian by pit-fall and free-hand collecting. Breeding crickets and recording by video of crickets behavior in laboratory make up the deficiency of biology data from references and field investigation. Crickets were reared in growth chamber (D /L: 12 /12, 25℃, RH 80%). We recorded the behavior of both circadian activity and reproductive behavior by video to analyse the on fixed action pattern. The egg stage was 35.69 ±1.99 days, and the longevity of male and female was 126.00 ±7.22, 127.70 ±8.30 days, respectively. Totally instars of most beach cricket was 8 instars (82.98%), fewer was 9 (17.02%). The first instar was 15.57 ±2.26 days, then reduced in 2~4 instar. Finally it increased accompany by instars. According to the result, we confirmed that T. formosanus lived in pebbled sandy band intensively (4 April: ANOVA, F=2.63, p=0.1049; 21 November: ANOVA, F=4.09, p=0.0382; 20 December: ANOVA, F=4.77, p=0.0250). For the circadian, the active time in the third period was longer than two light periods. The cricket was more active in the dark than in the light period. Male reversed its position and made a distinctive behavior, like vibrating or jerking, and moved with his posterior end directed toward the female’s head during courtship. Because of wingless, we presume that it is the same behavior for producing courtship song in the member of Nemobiidae. Because of the similar morphology, the other species T. ryukyuensis distributes over Ryukyu Island is considered that they are the same species. We hypothesize that the egg of beach cricket may disperse by Kuroshio Current from Taiwan east coast to Ryukyu. Results showed that T. formosanus has higher specificity in pebble sandy beach where are easily affected by human activity. We suggest that setting up a natural preservation zone in pebble sandy beach is necessary for protecting this treasuring species.