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Liu J, Tu F, Liu M, Wang J, Zhang Z. Antifertility effects of EP-1 (quinestrol and levonorgestrel) on Pacific rats (Rattus exulans). Integr Zool 2024; 19:127-142. [PMID: 37884475 DOI: 10.1111/1749-4877.12774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2023]
Abstract
Pest rodents pose a serious threat to island biodiversity. Fertility control could be an alternative approach to control the impact of rodents on these islands. In this study, we examined the antifertility effects of EP-1 baits containing quinestrol (E) and levonorgestrel (P) using a dose of 50 ppm E and P at three different ratios (E:P ratio = 1:2, 1:1, and 2:1) on Pacific rats (Rattus exulans) in the Xisha Islands, Hainan, China. Compared to the control group, all animals in EP-1 treatment groups showed significantly decreased food intake and body weight. In treated males, there were obvious abnormalities in testis structure and a significant decrease of relative seminal vesicle weight, but no significant effect on relative uterine and ovarian weights (g kg-1 body weight), or ovarian structure in females. Adding 8% sucrose to the original 50-ppm baits (E:P ratio = 1:1) significantly increased bait palatability for males and females. This dose induced uterine edema and abnormalities of ovarian structure in females but had no significant negative effect on the relative testis, epididymis, and seminal vesicle weights (g kg-1 body weight) or sperm density in males. In summary, 50-ppm EP-1 (1:1) baits have the potential to disrupt the fertility of females, and 8% sucrose addition to the EP-1 baits (E:P ratio = 1:1) could improve bait palatability. This dose disrupted the testis structure in males. Future studies are needed to improve bait acceptance and assess the antifertility effects of EP-1 (1:1) on Pacific rats in captive breeding trials and under field conditions.
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Affiliation(s)
- Jing Liu
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, Key Laboratory of Tropical Animal and Plant Ecology of Hainan Province, College of Life Sciences, Hainan Normal University, Haikou, Hainan, China
| | - Feiyun Tu
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, Key Laboratory of Tropical Animal and Plant Ecology of Hainan Province, College of Life Sciences, Hainan Normal University, Haikou, Hainan, China
| | - Ming Liu
- Secretariat Office, International Society of Zoological Science and Society and Journal Office, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Jichao Wang
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, Key Laboratory of Tropical Animal and Plant Ecology of Hainan Province, College of Life Sciences, Hainan Normal University, Haikou, Hainan, China
| | - Zhibin Zhang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
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Massei G, Jacob J, Hinds LA. Developing fertility control for rodents: a framework for researchers and practitioners. Integr Zool 2024; 19:87-107. [PMID: 37277987 DOI: 10.1111/1749-4877.12727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Fertility control is often heralded as a humane and effective technique for management of overabundant wildlife, including rodents. The intention is to reduce the use of lethal and inhumane methods, increase farm productivity and food security as well as reduce disease transmission, particularly of zoonoses. We developed a framework to guide researchers and stakeholders planning to assess the effectiveness of a potential contraceptive agent for a particular species. Our guidelines describe the overarching research questions which must be sequentially addressed to ensure adequate data are collected so that a contraceptive can be registered for use in broad-scale rodent management. The framework indicates that studies should be undertaken iteratively and, at times, in parallel, with initial research being conducted on (1) laboratory-based captive assessments of contraceptive effects in individuals; (2) simulation of contraceptive delivery using bait markers and/or surgical sterilization of different proportions of a field-based or enclosure population to determine how population dynamics are affected; (3) development of mathematical models which predict the outcomes of different fertility control scenarios; and (4) implementation of large-scale, replicated trials to validate contraceptive efficacy under various management-scale field situations. In some circumstances, fertility control may be most effective when integrated with other methods (e.g. some culling). Assessment of non-target effects, direct and indirect, and the environmental fate of the contraceptive must also be determined. Developing fertility control for a species is a resource-intensive commitment but will likely be less costly than the ongoing environmental and economic impacts by rodents and rodenticides in many contexts.
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Affiliation(s)
- Giovanna Massei
- Botstiber Institute for Wildlife Fertility Control, Department of Environment and Geography, University of York, Heslington, York, UK
| | - Jens Jacob
- Rodent Research, Institute for Epidemiology and Pathogen Diagnostics, Julius Kühn-Institute (JKI) Federal Research Institute for Cultivated Plants, Münster, Germany
| | - Lyn A Hinds
- CSIRO Health and Biosecurity, Canberra, ACT, Australia
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Fertility Control for Wildlife: A European Perspective. Animals (Basel) 2023; 13:ani13030428. [PMID: 36766317 PMCID: PMC9913817 DOI: 10.3390/ani13030428] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 01/23/2023] [Accepted: 01/25/2023] [Indexed: 01/31/2023] Open
Abstract
Trends of human population growth and landscape development in Europe show that wildlife impacts are escalating. Lethal methods, traditionally employed to mitigate these impacts, are often ineffective, environmentally hazardous and face increasing public opposition. Fertility control is advocated as a humane tool to mitigate these impacts. This review describes mammalian and avian wildlife contraceptives' effect on reproduction of individuals and populations, delivery methods, potential costs and feasibility of using fertility control in European contexts. These contexts include small, isolated wildlife populations and situations in which lethal control is either illegal or socially unacceptable, such as urban settings, national parks and areas where rewilding occurs. The review highlights knowledge gaps, such as impact of fertility control on recruitment, social and spatial behaviour and on target and non-target species, provides a decision framework to assist decisions about the potential use of wildlife fertility control, and suggests eight reasons for Europe to invest in this area. Although developing and registering contraceptives in Europe will have substantial costs, these are relatively small when compared to wildlife's economic and environmental impact. Developing safe and effective contraceptives will be essential if European countries want to meet public demand for methods to promote human-wildlife coexistence.
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IMAKANDO CI, FERNÁNDEZ‐GRANDON GM, SINGLETON GR, BELMAIN SR. Impact of fertility versus mortality control on the demographics of Mastomys natalensis in maize fields. Integr Zool 2022; 17:1028-1040. [PMID: 34496452 PMCID: PMC9786540 DOI: 10.1111/1749-4877.12580] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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 (F2,67 = 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.
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Affiliation(s)
- Christopher I. IMAKANDO
- Natural Resources InstituteUniversity of GreenwichChatham MaritimeKentUK,Department of Zoology and Aquatic SciencesCopperbelt UniversityKitweZambia
| | | | - Grant R. SINGLETON
- Natural Resources InstituteUniversity of GreenwichChatham MaritimeKentUK
| | - Steven R. BELMAIN
- Natural Resources InstituteUniversity of GreenwichChatham MaritimeKentUK
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Singleton GR, Lorica RP, Htwe NM, Stuart AM. Rodent management and cereal production in Asia: Balancing food security and conservation. PEST MANAGEMENT SCIENCE 2021; 77:4249-4261. [PMID: 33949075 DOI: 10.1002/ps.6462] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 05/02/2021] [Accepted: 05/04/2021] [Indexed: 06/12/2023]
Abstract
Rodents present a major problem for food security in Asia where smallholder farming families are particularly vulnerable. We review here recent developments in the biology and management of rodent pests in cereal cropping systems in Asia. The past decade has seen a strong focus on ecologically-based rodent management (EBRM), its adoption in field studies significantly increased rice yields (6-15%) and income (>15%) in seven Asian countries. EBRM principles have also been successfully applied to maize in China. We provide case studies on EBRM in Cambodia, on interactions between rodent pests and weeds, and on the importance of modified wetlands for biodiversity and rodent pest management. Knowledge on post-harvest impacts of rodents is increasing. One research gap is the assessment of human health impacts from a reduction of rodent densities in and around houses. We identify 10 challenges for the next decade. For example, the need for population modelling, a valuable tool missing from our toolbox to manage rodent pests in cereal systems. We also need to understand better the interactive effects of cropping intensification, conservation agriculture and climate change. Finally, new management approaches such as fertility control are on the horizon and need to be considered in the context of smallholder cereal farming systems and mitigating health risks from zoonotic diseases associated with rodents. © 2021 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
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Affiliation(s)
- Grant R Singleton
- Natural Resources Institute, University of Greenwich, Kent, UK
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, USA
- International Rice Research Institute, Los Baños, Philippines
| | - Renee P Lorica
- Natural Resources Institute, University of Greenwich, Kent, UK
- International Rice Research Institute, Los Baños, Philippines
- Department of Forest Biological Sciences, College of Forestry & Natural Resources, University of the Philippines Los Baños, Los Baños, Philippines
| | - Nyo Me Htwe
- Plant Protection Division, Department of Agriculture, Ministry of Agriculture, Livestock and Irrigation, Yangon, Myanmar
| | - Alexander M Stuart
- International Rice Research Institute, Los Baños, Philippines
- Pesticide Action Network UK, Brighthelm Centre, Brighton, UK
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Chen X, Hou X, Feng T, Han N, Wang J, Chang G. Anti-fertility effect of levonorgestrel and/or quinestrol on striped field mouse (Apodemus agrarius): evidence from both laboratory and field experiments. Integr Zool 2021; 17:1041-1052. [PMID: 34216194 DOI: 10.1111/1749-4877.12568] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The effect of combined levonorgestrel (P) and quinestrol (E) on the fertility of striped field mouse (Apodemus agrarius) has not been evaluated. We performed a series of experiments in both the laboratory and field to assess the effect of P and/or E on the fertility of A. agrarius. In the laboratory, to test the time-dependent anti-fertility effects of P and E, as well as their mixtures, 90 male striped field mice were randomly assigned to 6 treatment groups (n = 60), and a control group (n = 30). Mice in 3 treatment groups were administered 1 of the 3 compounds (1 mg⋅kg- 1 [body weight] EP-1, 0.34 mg⋅kg-1 E, 0.66 mg⋅kg-1 P) for 3 successive days (another half for 7 successive days) via oral gavage; mice were then sacrificed 15 and 45 days after initiating the gavage treatment. Our findings indicated that E and EP-1 treatment, but not P or control treatment, significantly decreased the sperm count in the caudal epididymis, as well as the weight of the testes, epididymides, and seminal vesicles. Additionally, fertile female mice mated with E- and EP-1-treated males produced smaller pups. These data indicate that E and EP-1 can induce infertility in male A. agrarius. In the field, the population density of A. agrarius was significantly influenced by EP-1, and the rodent density in the treatment group was lower than that in the control group. Overall, our results indicate that EP-1 is an effective contraceptive in A. agrarius, a dominant rodent species in the farmland.
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Affiliation(s)
- Xiaoning Chen
- Shaanxi Key Laboratory for Animal Conservation, Shaanxi Institute of Zoology, Xi'an, China.,College of Life Sciences, Shaanxi Normal University, Xi'an, China
| | - Xiang Hou
- Shaanxi Key Laboratory for Animal Conservation, Shaanxi Institute of Zoology, Xi'an, China
| | - Tuo Feng
- Shaanxi Key Laboratory for Animal Conservation, Shaanxi Institute of Zoology, Xi'an, China
| | - Ning Han
- Shaanxi Key Laboratory for Animal Conservation, Shaanxi Institute of Zoology, Xi'an, China
| | - Jing Wang
- Shaanxi Key Laboratory for Animal Conservation, Shaanxi Institute of Zoology, Xi'an, China
| | - Gang Chang
- Shaanxi Key Laboratory for Animal Conservation, Shaanxi Institute of Zoology, Xi'an, China
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Selemani M, Makundi RH, Massawe AW, Mhamphi G, Mulungu LS, Belmain SR. Impact of contraceptive hormones on the reproductive potential of male and female commensal black rats (Rattus rattus). Integr Zool 2021; 17:991-1001. [PMID: 34047451 DOI: 10.1111/1749-4877.12563] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The black rat is considered one of the world's top pests. With increased restrictions on rodenticides, new alternatives to manage rats are urgently needed. Research on the use of contraceptive hormones, levonorgestrel (LE), and quinestrol (QU), have been evaluated against some rodent species, and this research is the first study to assess these on black rats. Hormones were incorporated into rodent bait at 10 and 50 ppm concentrations singly and in combination (EP-1). Groups of 10 animals of each sex were fed the baits over 7 days. Lower bait consumption was observed with slight body mass reductions. On dissection, it was observed that the uterus was in a state of edema and male reproductive organs weighed less with reduced sperm counts/motility. The 2 most promising baits, 50 ppm QU and EP-1, were used to assess impact on pregnancy and litter size. Pregnancy was reduced from 70% success when both males and females consumed untreated bait, down to 30% when males had consumed contraceptive bait but females had not, and down to 0% when females had consumed contraceptive bait, regardless of whether they had paired with a treated or untreated male. Litter size in the untreated pairs was 8 pups, but only 4 pups in those cases where the male only had consumed the contraceptive. Further studies should investigate how long the effect lasts and its reversibility. Field studies at the population level may also shed light on the practicality of using contraceptive baits for black rats in different habitats.
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Affiliation(s)
- Mwajabu Selemani
- Department of Wildlife Management, Sokoine University of Agriculture, Morogoro, Tanzania
| | - Rhodes H Makundi
- Pest Management Centre, Sokoine University of Agriculture, Morogoro, Tanzania
| | - Apia W Massawe
- Pest Management Centre, Sokoine University of Agriculture, Morogoro, Tanzania
| | - Ginethon Mhamphi
- Pest Management Centre, Sokoine University of Agriculture, Morogoro, Tanzania
| | - Loth S Mulungu
- Pest Management Centre, Sokoine University of Agriculture, Morogoro, Tanzania
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