Juvenile hormone titer and morph-specific reproduction in the wing-polymorphic cricket, Gryllus firmus

Juvenile hormone titers and reproductive characteristics were measured in a dult wing and flight-muscle morphs of the wing-polymorphic cricket, Gryllus firmus, during the first week of adulthood. This species has three morphs: one flight capable morph with fully-developed wings and fully-developed fl ight muscles [LW(F)], one flightless morph with fully-developed wings and h istolyzed (non-functional) flight muscles [LW(H)], and another flightless m orph with underdeveloped (short) wings and underdeveloped flight muscles (S W), Both flightless morphs [LW(H) and SW] had larger ovaries which containe d a greater number of postvitellogenic eggs compared with the flight capabl e [LW(F)] morph. The juvenile hormone titer was significantly higher in SW compared with LW(F) females on days 3-7 of adulthood. On these days, the JH titer also was significantly higher in the other flightless morph, LW(H), compared with flight-capable [LW(F)] females as determined by one statistic al test, but did not differ significantly by another test. The JH titer was positively correlated with ovarian mass or terminal oocyte length, but not with the number of post-vitellogenic eggs. This study is the first direct comparison of juvenile hormone titers in adult wing morphs of a wing-polymo rphic insect. Results indicate that an elevated juvenile hormone titer may be at least partly responsible for one of the most distinctive features of wing-polymorphic species, the increased early fecundity of flightless femal es. (C) 2000 Elsevier Science Ltd. All rights reserved.