The effect of temperature on embryonic development and local adaptation in the life cycle of Eobiana engelhardti subtropica Bey-Bienko (Orthoptera: Tettigoniidae).

Abstract

Embryonic development in relation to life cycle adaptation was studied in the northern (Aomori, 40.6°N) and southern (Osaka, 34.9°N) strains of Eobiana engelhardti subtropica (formerly Metrioptera hime) (Orthoptera: Tettigoniidae). Eggs of the 2 strains showed similar thermal responses. At 20, 22.5, and 25°C, they developed to the mature embryonic stage without delay and entered an obligatory embryonic diapause (final diapause). At 27.5 and 30°C, on the other hand, embryonic development was markedly delayed. This retardation was more striking in the southern strain. Especially, summer diapause occurred in half-grown embryos at 30°C. A shift of temperature from 30°C to 20 or 25°C terminated summer diapause and the eggs started to develop. The final diapause is never terminated if kept at high temperatures. Final diapause requires an exposure to a cold temperature of 15°C or lower and the intensity is higher in the southern strain. Adults of the southern strain emerged in mid June or earlier and those of the northern in early-mid July. In outdoor experiments, the developmental rate decreased more conspicuously in the eggs laid earlier in the southern population. As a result, the eggs reached the final-diapause stage in autumn more synchronously than expected from the long egg-laying period. The decreased developmental rate and summer diapause appear to secure survival in the hot season and ensure reaching the embryonic diapause stage synchronously in autumn. The local variation in the final-diapause intensity seems to be related to the heat units in autumn which might otherwise cause untimely hatching.

Termination of reproductive diapause in the rice water weevil with particular reference to the effects of temperature

“…Temperatures can usually regulate summer diapause of insects, with diapause development generally being delayed under high temperatures, while being greatly enhanced under low-middle tempera- tures (Tauber et al, 1986, and references therein;Wipking, 1995;Xue et al, 2001;Higaki and Ando, 2002). In the present study, the diapause development of 1st-generation RWW adults was very slow under 25°C while it was apparently much more rapid under 10-20°C (Fig.…”

Effects of crowding and photoperiod on wing morph and egg production in Eobiana engelhardti subtropica (Orthoptera: Tettigoniidae)

“…2 and Table 3). Eggs of this katydid typically require a long time to reach the diapause stage (about 50 days at 20°C: Higaki and Ando, 2002). Therefore, the short-day acceleration of oviposition may enable eggs to reach the diapause stage before winter.…”

Cold winter temperatures condition the egg-hatching dynamics of a grape disease vector

“…However, diapause entry or termination is subjected to polymorphism, which is supposed to allow risk-spreading strategies (Menu and Desouhant 2002 ). The effect of chilling on the end of diapause and its consequences on insect emergence is well known in orders as diverse as Orthoptera (Higaki and Ando 2002 ), Diptera (Collier and Finch 1983 ), or Lepidoptera (Wipking 1995 ). Better understanding of this species’ life history traits and behavior will aid our understanding of its geographical range, and this in turn will improve one’s ability to forecast the occurrence of this disease.…”