Abstract: Parascaris equorum (ascarid; roundworm) is a common nematode parasite which occurs in the small intestine of immature horses world-wide. Adult female ascarids lay eggs in the small intestine, and these eggs pass into the environment within the feces of the host. P. equorum is one of the rare nematodes which induce absolute acquired immunity. Most horses become immune during the first year of life, so patent ascarid infections are rarely diagnosed in horses over two years of age. The aim of this study was to determine the prevalence of infection with parascaris equorum in Tehran’s riding clubs. The prevalence and rate of infection was determined based on the coproscopic examination. Fecal samples were tested for the presence of parascaris using suspend method. In this investigation, 442 fecal samples of horses from North-East of Tehran’s riding clubs examined. From the viewpoint of parascaris roundworms, fecal samples were obtained from each box separately and send in containers with plastic lid. The samples were then transferred to the parasitology lab for further examination. The infection was recognized based on the observation of parascaris eggs in coproscopic examination. The infection rate in the foal in this study was zero percent. Another interesting result was increasing the infection rate in horses of 10 years or even older and gelding. Out of 442 samples, the infection rate in the samples taken in summer, was 3.16%, and in the fall, winter and spring it was 2.4%, 10% and 3.16% respectively. The infection rates in relation to the age, sex, excursion condition, seasons and deworming programs was studied too. The results showed that the local and the imported horses should be monitored parasitologically, because endoparasites may create a major epizootiolocall problem when these animals are kept in an organic raising system. Deworming program is to be continued with proper methodology, dose and throughout the productive age of the horses.

Abstract: Parental care can be costly to a parent in terms of both time and energy invested in the young. In species with cuckoldry or brood parasitism not all of the young under a parent's care are necessarily offspring. In such cases, distinguishing between kin and non-kin, and investing only in the former (nepotism), can be advantageous. Bluegill sunfish ( Lepomis macrochirus) are characterized by paternal care and cuckoldry, and care-providing males appear to show nepotistic behaviours. Here, we investigated nestling recognition in bluegill, determining whether parental males can differentiate between young from their own nest (familiar and related) and young from non-neighbouring nests (unfamiliar and unrelated) using (1) visual and chemical cues, and (2) chemical cues only. In the first experiment, wild-caught parental males were presented with samples of eggs or fry (newly hatched eggs) collected from their own nest or a foreign nest and placed on opposite sides of an aquarium. The time these parental males spent associating with each sample, and their “pecking” behaviours (indicating cannibalism), were recorded. Parental males showed no preference between eggs from their own nest and eggs from a non-neighbouring nest, but they preferred to associate with fry from their own nest over foreign fry. There also was a positive relationship between male body size and the time spent associated with fry from their own nest. Parental males pecked at foreign fry more than 5 times as often as fry from their own nest, though this difference was not statistically significant. In the second experiment, fry that were collected from the nest of a wild-caught parental male or a non-neighbouring nest were placed in different containers and the water from each was dripped into opposite ends of an aquarium. The time the male spent on each side was recorded. In this case, parental males spent more time near the source of water conditioned by unrelated fry, but there was a positive relationship between male condition (fat reserves) and the time he spent near the source of water conditioned by fry from his own nest. Results confirm that chemicals cue nestling recognition by parental male bluegill.