Intestinal infestation by gregarines in farmed whiteleg shrimp Penaeus vannamei in Nayarit, Mexico.

Abstract

The presence of gregarines in shrimp farming is
associated with a low growth rate. In this industry, growing time is critical to the crop’s success. This work describes the intestinal infestation by gregarines in Penaeus vannamei and evaluates a method of control of the parasite. Sampling was carried out from May-August (dry season) and AugustNovember (rainy season) on four farms. The degree of gregarine infestation, prevalence, and their relationship with salinity was determined. Finally, we tested the commercial antiparasitic PREOXOL^® (oxibendazole) at 1.5 % as a control against these parasites in commercial production.
The prevalence of gregarines in both crop cycles was
high, ranging between 75 and 90 % in the dry season and
between 70 and 87 % in the rainy season. The degree of
severity of the infestation was higher in the dry season. The salinity recorded during the dry season ranged between 26 and 47 UPS, while it was between 6 and 26 UPS in the rainy season. We found a positive correlation between the degree of severity and salinity. The antiparasitic reduced the prevalence of gregarines by more than 90 %, while the severity decreased by up to three degrees. There is a positive correlation between the degree of severity and salinity, but not with prevalence. The control method used with PREOXOL^® turned out to be highly efficient in commercial shrimp production.