BACKGROUND The epidemiological importance of the mosquito Aedes aegypti as a vector of multiple human pathogens has generated a growing number of studies on the physiology and behaviour of its blood-feeding females. The activity of oviposition is one of the critical elements contributing to the expansion of Ae. aegypti's populations. Although there is a vast literature about oviposition behavio...

The following hypotheses were tested for groups of simultaneous hermaphrodites Biomphalaria tenagophila: (a) snails that have low reproductive success during the process of self-fertilization do not increase their reproductive success after the end of grouping; (b) the copulation behaviour and the presence of one snail whose eggs have a low viability rate influence the partner's reproductive su...

In many species of social Hymenoptera, unmated workers can lay eggs that will produce males by parthenogenesis. Nevertheless, in queenright honey bee colonies (Apis mellifera), worker reproduction is low. One possible mechanism for this difference is worker policing, the removal of worker-laid eggs by other workers. This behavior can evolve in species in which queens are multiply mated, where w...

The aim of this study was to evaluate the effects of the addition of antioxidants (vitamin E, β- mercaptoethanol and their combination) to semen extender.  Progressive motility, viability and pH of fresh ram semen were examined. Ejaculate samples were collected with artificial vagina from three Ghezel-Merinose rams (3 years old) during non- breeding reproduction season. Semen was diluted with a...

Worker policing, wherein social insect workers prevent their sisters from reproducing by eating worker-laid eggs, is recognized as a textbook example of kin selection in action. However, the evolutionary basis of policing was recently challenged in a study that suggested that police-workers remove worker-laid eggs not because rearing workers' sons reduces worker fitness, but merely because work...

The aim of this study was to evaluate the effects of the addition of antioxidants (vitamin E, β- mercaptoethanol and their combination) to semen extender.  Progressive motility, viability and pH of fresh ram semen were examined. Ejaculate samples were collected with artificial vagina from three Ghezel-Merinose rams (3 years old) during non- breeding reproduction season. Semen was diluted with a...

Spermatozoa sexing requires a diluent that can protect and provide an optimal environment to maintain the quality of spermatozoa. This study targets determine effectiveness adding sucrose tris-egg yolk on sperm swamp buffaloes produced by with egg albumin method. Semen was collected once week for 12 consecutive weeks artificial vagina from three male at Indonesian Center Animal Research Develop...

Experiment was conducted to evaluate the effect of different levels of egg yolk for coating and storing spermatozoa. Ejaculates were collected from four rams. In each session, second ejaculates (n=4) were collected in a tube containing 1 mL coating buffers which were prepared by 10, 15 or 20% egg yolk plus Tris-fructose. Samples were pooled, centrifuged and the supernatant removed in the labora...

BACKGROUND Helminths is a endoparasites that cause the major losses for profitable sheep production in Brazil. The increased development of resistant strains of endoparasites have enforced the search for sustainable alternatives. The aim of this paper was to provide information about endoparasites control with banana leaves in infected sheep as alternative control strategies and see its viabili...

Many animal species face periods of chronic nutritional stress during which the individuals must continue to develop, grow, and/or reproduce despite low quantity or quality of food. Here, we use experimental evolution to study adaptation to such chronic nutritional stress in six replicate Drosophila melanogaster populations selected for the ability to survive and develop within a limited time o...