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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., (© 2021 The Authors. Integrative Zoology published by International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and John Wiley & Sons Australia, Ltd.)

This paper investigates the importance of ecologically based rodent management in the light of the current food crisis, and the potential effects of this approach on the position of the undernourished. Hunger and food prices are on the rise owing to shortages that can be traced to reasons such as climatic extremes, use of crops for biofuels, reduced growth in yields which lag behind population growth, reduced world stocks and lack of sufficient investment in maintaining the irrigation infrastructure. For the undernourished this is problematic as they are most vulnerable to the rise in food prices. Very often, agricultural experts focus on an increase in agricultural production to reduce food prices. It is postulated in this article that almost 280 million undernourished could additionally benefit if more attention were paid to reducing pre- and post-harvest losses by rodents. Moreover, rodent-borne diseases would decrease, diseases that can be catastrophic to the livelihoods of the poorest of the poor., (Copyright (c) 2009 Society of Chemical Industry.)

Food security is a major concern at a global level. The impacts of rodents pre- and post-harvest are legendary, as too are their incursions on the day-to-day lives of people. As vertebrate pest managers we need to move beyond the rhetoric and provide effective management approaches. If on an annual basis we can reduce by 5% the food that rodents eat and spoil globally, then this could save 70 million tons of grain. From the 1960s to the mid 1990s the dominant paradigm for rodent control was the widespread use of chemical rodenticides. Rodent biologists were forced to rethink this reliance on chemical rodenticides because of human health and safety issues, lack of efficacy, detrimental effects on non-target species, and the development of resistance to the anticoagulant rodenticides. Some 15 years ago, ecologically-based rodent management (EBRM) was formally described based on adaptive research conducted to manage irruptions of mouse populations in Australia and rats in Southeast Asia. EBRM builds on foundation work conducted in the 1940s and 1950s by ecologists such as Elton, Chitty, and Davis; research that was marginalized with the advent of cheap and effective rodenticides. EBRM has had a significant impact since its formulation: it has been formally adopted by the governments of Indonesia and Vietnam as their national policy for rodent management in agricultural systems, and is the main rodent management paradigm in at least 30 countries. A challenge is to address not only chronic rodent problems in agricultural landscapes but also the acute outbreaks that cause tremendous impacts on rural communities. An important component of EBRM has been the incorporation of sociological research. I provide a retrospective view of what has been achieved by ecologists and sociologists over the past 15 years, identify countries where progress has been promising, and then provide thoughts on some promising global research challenges.

This article provides an overview of the impact of rodents on agriculture, health, and biodiversity, with a particular focus on Africa. It acknowledges that while rodents make up a significant portion of mammalian species, only a small percentage of them have negative effects. The article highlights the 7th International Conference on Rodent Biology and Management, which concentrated on rodent biology and biodiversity in African highlands and mountains. It discusses the shift in focus from previous conferences, including increased research on fertility control of rodents and a greater emphasis on the One Health approach to rodent-borne diseases. The article covers various topics related to rodent biology and management, such as reducing flea and rodent populations simultaneously to prevent disease transmission and efforts in New Zealand to eradicate invasive rodents for the conservation of endemic wildlife. It also explores adaptations of rodent sensory systems, developments in rodent taxonomy, strategies for dealing with dietary toxins, and the use of African giant pouched rats for tasks like landmine detection and disease detection. The article underscores the importance of long-term population studies in understanding rodent populations and their impact on agriculture and human health. It concludes by acknowledging the contributions of researchers in the field and announcing the next International Conference on Rodent Biology and Management in 2025. [Extracted from the article]

The rice field rat, Rattus argentiventer, is a significant pest of rice in Southeast Asia. Fertility control methods have the potential to provide safe and effective alternatives to control methods that often include indiscriminate use of rodenticides or electric barriers. The aim of this laboratory study was to assess uptake of bait coated with different concentrations of the contraceptive hormones, quinestrol (E) and levonorgestrel (P), delivered alone and in combination (i.e. EP‐1) and determine the short‐term effects on reproductive parameters of adult male and female R. argentiventer. In Experiment 1, 2 concentrations of E, P, and EP‐1 (10, 20 ppm) were fed to groups of wild‐caught rats for 7 days. In females, both E and EP‐1 induced uterine edema. In males, EP‐1 reduced epididymis and seminal vesicle weights and lowered sperm motility. However, these responses were inconsistent due to low bait acceptance, especially with increasing concentrations. In Experiment 2, EP‐1 (0, 20, 50, 100 ppm) was administered by oral gavage daily for 7 days to male R. argentiventer. There were significant reductions in epididymal and seminal vesicle weights for all oral doses of EP‐1, in sperm counts for the 50 ppm dose, and in sperm motility for the 20 and 50 ppm doses compared to the control group. To select the optimum dose of EP‐1, we must address the poor acceptance of contraceptive‐coated baits by rice field rats. Further research is required to improve the palatability of EP‐1 and to test its uptake under field conditions. [ABSTRACT FROM AUTHOR]

Rodents and weeds are important pests to rice crops in Southeast Asia. The interaction between these 2 major pests is poorly documented. In temperate cereal systems, seeds of grass weeds can be an important food source for rodents and weed cover along crop margins provides important refuge for rodents. In 2012 and 2013, a replicated study (n = 4) in Bago, Myanmar compared 4 treatments (rodents and weeds; no rodents and weeds; rodents and no weeds; no rodents and no weeds) each of 0.25 ha in transplanted rice. Weeds were managed with hand weeding in the wet season, and hand weeding and herbicides in the dry season. Plastic fences were installed to exclude rodents. We examined the weed cover and relative abundance of weed species, rodent damage, rodent population dynamics and rice yield loss caused by rodents and weeds. The dominant rodent species was Bandicota bengalensis. In the dry season, Cyperus difformis was dominant at the tillering stage and Echinochloa crus‐galli was the dominant weed species at the booting stage. In the wet season E. crus‐galli was a dominant weed throughout the season. Damage by rodents was higher in the dry season. There were larger economic benefits for best weed management and effective rodent control in the dry season (258 US$/ha) than in the wet season (30 US$/ha). Concurrent control of weeds in and around rice fields combined with coordinated community trapping of rodents during the early tillering stage and ripening stage of rice are recommended management options. [ABSTRACT FROM AUTHOR]

In this study, the ecological effects of culling programs are considered in the context of rodent pest management. Despite the escalation of rodent problems globally, over the past quarter of a century there have not been many new developments in culling programs directed at managing these populations. There is a strong reliance on broad scale use of chemical rodenticides or other lethal methods of control. The ecological consequences of culling programs based on chemical rodenticides and bounty systems are considered. Although rodents cause tremendous economic hardship to people on a continental scale, usually less than 10% of species cause substantial impacts. Indeed, many species of rodent provide important “ecological services” and, given that culling programs rarely distinguish between rodent species, often the non-pest rodents are at grave risk. Rodent control is conducted with little appreciation of what proportion of the population would need to be culled for a significant reduction in economic damage. In Indonesian rice fields, once rodent densities are high then a reduction in yield loss from 30% to 15% would require more than 75% of the population to be culled; a reduction to less than 5% yield loss would require more than a 95% cull. The negative ecological consequences of culling can be better managed if the method is specifically tailored to the species that need to be managed. A greater emphasis on ecologically-based rodent management would assist markedly in reducing the unwanted and unintended effects of culling. [ABSTRACT FROM AUTHOR]