Impact of fertility versus mortality control on the demographics of Mastomys natalensis in maize fields

Abstract

The multimammate mouse, Mastomys natalensis, is the most common rodent pest species in sub-Saharan Africa. Currently, rodenticides are the preferred method used to reduce the population of rodent pests, but this method poses direct and indirect risks to humans and other non-target species. Fertility control is a promising alternative that has been argued to be a more sustainable and humane method for controlling rodent pests. In this study, we compared the effectiveness of fertility control bait EP-1 (quinestrol (E) and levonorgestrel (P), 10 ppm) and an anticoagulant rodenticide bait (bromadiolone, 50 ppm) on the population dynamics of M. natalensis in maize fields in Zambia during 2 cropping seasons. M. natalensis was the most abundant species in maize fields (77% of total captures). Fertility control reduced the number of juveniles and suppressed population growth of M. natalensis at the end of the 2019-2020 cropping season. The population density initially decreased after rodenticide treatment, but the population rapidly recovered through immigration. None of the treatments influenced maize damage by rodents at germination (F 2,67 = 1.626, P = 0.204). Applying the treatments during the maize seeding time was effective at suppressing population growth at the end of the cropping season than application the month before maize seeding. This research indicates that a single-dose delivery of EP-1 and rodenticide have comparable effects on the population dynamics of M. natalensis. These findings are important in developing fertility control protocols for rodent pest populations to reduce maize crop damage and improve yields.

Synergistic effects of EP‐1 and ivermectin mixture (iEP‐1) to control rodents and their ectoparasites

“…Since the report by Zhang et al ., 13 the anti‐fertility effect of EP‐1 on wild rodents has been confirmed by many laboratory and field studies 15,17–19,21,36,38–40 . In this study, we found EP‐1 and iEP‐1 significantly reduced the weight of testis and epididymis of male long‐tailed hamster, Mongolian gerbils, and mid‐day gerbils, increased the weight of the uterus while inducing uterus oedema, similar to previous studies.…”

Fertility control of rodent pests: recent developments from lab to field

“…One example in this issue is the first laboratory study of the effects of E, P and EP-1 on the subterranean rodent, the plateau zokor (Eospalax baileyi), a key native species competing with livestock on the Qinghai−Tibet plateau (Kang et al 2022). The early field results using EP-1 for management of the multimammate rat in Tanzania (Imakando et al 2021), and the striped field mouse in China (Chen et al 2021), also reported in this special issue, are promising. Larger areas of treatment and more replication in field situations are required to see if this research can lead to successful broad scale management of various pest rodents.…”

“…The early field results using EP‐1 for management of the multimammate rat in Tanzania (Imakando et al . 2021), and the striped field mouse in China (Chen et al . 2021), also reported in this special issue, are promising.…”

The status of fertility control for rodents—recent achievements and future directions

“…Field trials at management scale (e.g. Imakando et al 2021) should be conducted to compare baiting strategies (burrow baiting, bait stations, broadcast) regarding their suitability for delivering effective doses to target species and minimizing uptake by nontargets. Bait markers seem a suitable tool for such studies (Jacoblinnert et al 2021).…”