Variations in body length, weight, fat content and survival in Coccinella septempunctata at different hibernation sites

Abstract

Adults of Coccinella septempunctata L. (Coleoptera; Coccinellidae) were sampled in four overwintering sites: one in England and three at different altitudes in the Czech Republic (350–1420 m above sea level) in autumn 1992 and spring 1993. Body length, dry weight and fat weight were measured. There were significant differences in body length between sampling sites in spring 1993, but not in autumn 1992. The average sex ratio (♀) in all samples was 1:0.60 in 1992 and 1:0.72 in 1993. Females were significantly larger and heavier, and contained more fat than males in both sampling periods. Dry weight and fat weight were positively correlated to body length at all sampling sites except at Ruzyne, in the Czech Republic. Adults hibernating at higher altitudes and away from their breeding and feeding habitats had significantly more fat than those hibernating at lower altitudes. Fat reserves were reduced by 30% during the hibernation at the top of the Krkonose mountain, in the Czech Republic, where temperatures were much lower, but more than half of the fat reserves were consumed during the overwintering period at the other sampling sites. The significance of body length and fat reserves in relation to adult hibernation sites and overwintering survival is discussed.

Diapause/Dormancy

“…A high proportion in the meadow of small individuals, less capable of long fl ight, indicated poor nutrition of larvae (and/ or pre -hibernation adults) and presence of local ladybirds. In this sample medium sized individuals had only 1.7% survival, while in the high altitude sample the survival was 83.3% in medium sized males and 86.7% in medium sized females (Zhou et al 1995, Hon ě k 1997. As the cause of mortality was not studied, it cannot be excluded that the high altitude hill top sample was less prone to fungal infection (Chapter 8.4.3 ) and this contributed to higher survival.…”

“…Females, in which diapause was induced in the laboratory at 12L:12D and 18 ° C had 20% less lipids (0.164 mg). Zhou et al (1995) reported, also for the Czech Republic, a slightly higher content of fat in C. septempunctata females, sampled in mid -September in mountains (1420 m a.s.l. : 9.4 mg per individual) than in those from a hill (400 m a.s.l.…”

“…Not only have most species been ignored , but even in monospecifi c studies, numerous for C. septempunctata , intraspecifi c variation has rarely been considered. Comparative studies on diapause intensity or overwintering survival , such as by Hodek et al (1977) and Zhou et al (1995) , have remained rare and should be extended. Also, geographic variation in diapause expression (which has often attracted interest in other insect groups) has been a rare topic even with common coccinellid species, such as C. septempunctata.…”

Insects as Food for Insectivores

“…In several families within the order Lepidoptera, males contain greater fat reserves than females (Beenakkers et al, 1985). In most other species, females have greater fat reserves than males (Lease and Wolf, 2011;Nestel et al, 2005;Zhou et al, 1995). In species that use accumulated energy reserves obtained during their larval stages for reproduction, greater reserves would have a positive effect on fecundity because eggs have a high lipid content and therefore provide fitness advantages (Beenakkers et al, 1985;Downer and Matthews, 1976;Lease and Wolf, 2011).…”

Overwintering of Coccinella septempunctata (Coleoptera: Coccinellidae) at different altitudes in the Karkonosze Mts, SW Poland

“…Beetles can hibernate near their breeding sites: at forest edges, clearings, wind breaks, near isolated shrubs or can migrate to the hibernacula situated on the summits of prominent hills or mountains (Honek, 1989;Hodek et al, 1993;Hodek & Honek, 1996). Migrants and indi viduals remaining for winter in the proximity of breeding sites differ in some biological and ecological characters such as the intensity of diapause, duration of the dor mancy period, female/male ratio, fat reserves or mean body size (Hodek et al, 1977;Honek, 1989;Zhou et al, 1995). While relatively large, fatty and predominantly female individuals arrive at the prominent dormancy sites during August to hide among the stones or in grass tus socks, the smaller ones, staying at lower situations, can be found on plants even in October (Honek, 1989).…”