Maternally derived yolk androgens affect many aspects of phenotypic development. To explore this phenomenon I injected clutches of American kestrels (Falco sparverius) with one of three different dosages of testosterone + androstenedione or with vehicle. Morphological measurements taken from nestlings 26 days after hatching showed no significant treatment effect. In 2007, nestlings with more yo...

The responses of eggs in diapause and the infective stage of the nematode, Strelkovimermis spiculatus, to larvae of its host, Culex pipiens pipiens, were investigated in the laboratory. The results indicated that the presence of the host induced the egg hatching. The hatching rate increased when larger numbers of host larvae were present. Second instar mosquito larvae induced significantly high...

There has been a great deal of recent attention on the suspected increase in amphibian deformities. However, most reports of amphibian deformities have been anecdotal, and no experiments in the field under natural conditions have been performed to investigate this phenomenon. Under laboratory conditions, a variety of agents can induce deformities in amphibians. We investigated one of these agen...

Background & Aim: Tetranychus urticae Koch is one of the most important pests of crops, ornamental and greenhouse plants in the world and, can damage to 900 plant species. Resistances to pesticides and acaricides have guided researches to introduce new methods to control T. urticae. Botanical pesticides are an important group of natural productions that are usually safer than ...

Ascidian species (Tunicata: Ascidiacea) usually have tailed, hatching tadpole larvae. In several lineages, species have evolved larvae that completely lack any tail tissues and are unable to disperse actively. Some tailless species hatch, but some do not hatch before going through metamorphosis. We show here that ascidian species with the highest speciation rates are those with the largest rang...

Females of Culex pipiens pallens are rarely inseminated at temperatures above 30 degrees C. Insemination and egg-hatching rates (F2) were examined in females of hybrids (F1) between Culex pipiens pipiens and Culex pipiens quinquefasciatus at 25 degrees C and 30 degrees C to examine temperature-dependent reproductive activity. Insemination rates were very high in hybrid females (F1) at 25 degree...

Accelerated hatching is one of few defences available to embryos, and is effective against many egg-stage risks. We present the first analysis of genetic variation in hatching plasticity, examining premature hatching of American toad embryos in response to pathogenic water moulds. We reared eggs from half- and full-sib families in the presence and absence of water mould. Hatching age and hatchl...

Experimental studies have shown heart rates to decrease from embryo to hatchling stage in turtles, remain steady in skinks, and increase in birds. However, no snake species has been studied in this regard. I recorded heart rate evolution trajectories from embryo to juvenile stage in 78 eggs from two species of European Natricine snakes. Unexpectedly, snakes behaved more like birds than turtles ...

the zebra cichlid cichlasoma nigrofasciatum is a species famous for its behaviors of biparental care. this study was conducted to examine the effect of parental care and their size on the reproductive success of this fish. hatching rate (hrs) has significant difference (p

The life history of Enochrus quadripunctatus Herbst was studied in the laboratory. The duration of each developmental stage, larval behavior, and preimaginal mortality rate were determined. It takes the insect a total of 43 days from hatching to reach the adult stage, with a high mortality rate in the first stadium. The mortality rate decreases as the beetle passes through the immature sta...