Fertility control of Rattus nitidus using quinestrol: effects on reproductive organs and social behavior

Abstract

Fertility control has been identified by studies in the laboratory and the field as a more appropriate and long-term control strategy for rodent pests than lethal control. In this study, we investigated the effects of quinestrol on mass of reproductive organs and on social behaviors in female and male Indochinese forest rat (Rattus andamanensis (Blyth, 1860)] using approach of morphometrics and genetics). [corrected]. A total of 16 adult females and 16 adult males were randomly assigned to 4 groups. One male and one female group were fed rice with 0.005% quinestrol by weight for 7 days, and another 2 groups were fed rice only. After 7 days, rats were assigned to 10 min dyadic encounters between groups, and investigation, aggression, defense and attack latency were quantified. All animals were killed on day 10, and reproductive organs were dissected and weighed. Dyadic encounter data showed that there were obvious changes in social behaviors of quinestrol-treated rats. Quinestrol significantly inhibited the investigative behavior of quinestrol-treated males toward control females in Rattus nitidus, but seldom affected investigation between control males and quinestrol-treated females. Aggression of control females toward quinestrol-treated males was higher than that of quinestrol-treated females, and defense of quinestrol-treated males toward control females was more remarkable than that of control males. Quinestrol remarkably decreased wet masses of epididymis and spermotophore in males and ovaries in females, but had no effect on wet masses of testes and uteri after quinestrol treatment. These results indicate that the anti-fertility effects of quinestrol on R. nitidus are attributed to not only suppressing reproductive organs but also impacting social behaviors associated with territory defense and mate choice.

Effect of synthetic hormones on reproduction in Mastomys natalensis

“…Similar results have been reported in Mongolian gerbils ( Meriones unguiculatus ) (Lv and Shi 2011 , 2012 ) after consuming bait containing quinestrol but not after consuming levonorgestrel. However, Liu et al ( 2013 ) reported that quinestrol had no effects on the body weight of Rattus nitidus of either sex over seven days of treatment. In the current study, animals treated with quinestrol and levonorgestrel alone experienced much lower weight loss than those treated with the quinestrol + levonorgestrel combination.…”

“…However, such changes to the uterus are not found in all rodents treated with these fertility compounds. Zhao et al ( 2007 ) reported no significant differences in ovaries and uteri of Brandt’s voles treated with quinestrol, levonorgestrel and their combination, whereas Liu et al ( 2013 ) found reduced weight of ovaries but not uteri of Rattus nitidus treated with quinestrol. Lv and Shi ( 2011 ) also reported increased gonadosomatic indices of uteri and reduced gonadosomatic indices of ovaries after quinestrol treatment in Mongolian gerbils.…”

Jump-Starting Urban Rat Research: Conspecific Pheromones Recruit Wild Rats into a Behavioral and Pathogen-Monitoring Assay

“…Food-based rat attractants are limited due to significant bias in gender, and age class. Therefore, this approach offers a mechanism to remove age and gender bias, and improve the efficacy of attracting rats for removal or injection of females for injectable contraceptives (Liu et al, 2013).…”

Recovery of fertility in quinestrol‐treated or diethylstilbestrol‐treated mice: Implications for rodent management

“…Recently, this mixture has been tested for its ability to reduce the fertility of rodents. The mixture (coded as EP-1) has been shown to have anti-fertility effects on several wild rodent species, such as Brandt's voles (Lasiopodomys brandti) (Zhang et al 2004;Zhao et al 2007), gray hamsters (Cricetulus migratorius) (Zhang et al 2004), midday gerbils (Meriones meridianus) (Zhang et al 2004), greater long-tailed hamsters (Tscherskia triton) (Zhang et al 2005(Zhang et al , 2006, Djungarian hamsters (Phodopus campbelli) (Wan et al 2006), Mongolian gerbils (Meriones unguiculatus) (Huo et al 2007) and field rats (Rattus nitidus) (Liu et al 2013). Under field conditions, EP-1, especially quinestrol, was found to significantly decrease the reproduction of plateau pikas (Ochotona curzoniae) (Liu et al 2012a) and Mongolian gerbils (Fu et al 2013).…”