Some aspects of the life history and reproductive biology of Gerris remigis Say and Gerris buenoi Kirkaldy (Heteroptera) on the Avalon Peninsula of Newfoundland.

Sheppard, Sarah Jacinta (Murray) (1975) Some aspects of the life history and reproductive biology of Gerris remigis Say and Gerris buenoi Kirkaldy (Heteroptera) on the Avalon Peninsula of Newfoundland. Masters thesis, Memorial University of Newfoundland.

[English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (3MB)

Abstract

Specimens of Gerris remigis Say and Gerris buenoi Kirkaldy were studied in the field and laboratory. Life history, ovarian cycle and changes in weight were studied in the field or from field specimens while egg and nymphal development, reproductive diapause and winter inactivity were studied in the laboratory. -- Adults of both species emerged the first week of August 1974, entered obligatory reproductive diapause and inactivity in the fall and resumed activity in the spring. Copulation took place from April on, oviposition occurred for the first time 19. - 20. June in G. remigis and G. buenoi and a second time 28. - 29. June for G. buenoi. Nymphs of both species appeared 1. July 1974, and moulted five times in about 5 weeks in the field. -- Both species follow a yearly ovarian cycle. Rudiments appear and develop serially from posterior to anterior in each of 4 ovarioles in 2 ovaries. G. remigis develops 6 eggs per ovariole without a break while G. buenoi develops 3 per ovariole, ovulates and oviposits these and repeats the process. G. remigis starts ovarian development in the fall while G. buenoi starts in the spring. -- Changes in weight throughout the summer can be accounted for in part by changes in the ovarian cycle, appearance of new adults and, in late summer deposition of fat reserves. -- Exposure to 5°C, 10°C, 15°C and 20°C at 8 hours light to 16 hours dark (8L : 16D), 12L : 12D and 16L : 8D failed to break reproductive diapause or inactivity. -- Higher temperatures and longer photoperiods inhibited the limited amount of ovarian development that is carried out in the fall. None of the regimes had any effect on the ovaries of G. buenoi. The lower the temperature and the shorter the photoperiod the more of both species survived the regimes.

Actions (login required)

View Item