The magnitude of oviposition as well as the size, shape and the number of eggs per of egg rafts egg raft were determined after gravid Culex quinquefasciatus Say oviposited on water treated with water dispersible granules (WDG) of Bacillus thuringiensis ssp. israelensis (Bti) and on untreated water. The mean number of eggs/raft was lower in the treated than in the untreated water. Bti concentrat...

A8s~~nc~.-From May through July, 1993-1998 and 2001, effects of Brown-headed Cowbird (Molothrus ater) parasitism on 36 Warbling Vireo (Vireo gilvus) nests were documented in southwest Colorado. Overall parasitism was 75.0% and was the major source of nest failure. Among vireo nests that were not depredated, a significantly lower proportion of parasitized nests (10.2%) than nonparasitized nests ...

Heritability of egg size is approximately 60%-a very high value compared to the heritability of most other economic characters-and indicates that individual selection for egg size is to be preferred to family selection. A further simplification of the problem of changing the egg size of a flock by breeding selection is possible as a result of a study of genetic correlations between the weights ...

We have developed and characterized cell-free systems active in translation from unfertilized eggs, 30-min zygotes and hatched blastulae of the sea urchin Strongylocentrotus purpuratus. The ion concentrations selected for preparation of the lysates were 150 mM-K+, 40 mM-Na+, 40 mM-Cl-, 5 x 10(-7) M free Ca2+ and 1 mM free Mg2+. It was necessary to include the ribonuclease inhibitor RNas in the ...

Eggs often suffer high levels of predation and, compared with older animals, embryos have few options available for antipredator defence. None the less, hatchlings can escape from many predators to which eggs are vulnerable. I studied early hatching as an antipredator defence of red-eyed treefrog embryos, Agalychnis callidryas, in response to egg predation by social wasps (Polybia rejecta). Red...