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Beatham SE, Stephens PA, Goodwin D, Coats J, Thomas E, Rochester I, Massei G. An assessment of seasonal bait uptake by individual grey squirrels to develop a delivery system for oral contraceptives. PEST MANAGEMENT SCIENCE 2024. [PMID: 39248040 DOI: 10.1002/ps.8379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 07/31/2024] [Accepted: 08/05/2024] [Indexed: 09/10/2024]
Abstract
Globally, human-wildlife conflicts continue to increase, owing to human population growth and expansion. Many of these conflicts concern the impacts of invasive non-native species. In the UK, the invasive, non-native grey squirrel Sciurus carolinensis negatively affects tree health and has caused the decline of the native red squirrel Sciurus vulgaris. Oral contraceptives are being developed to manage the impacts of the grey squirrel. To be effective, contraceptives will need to be deployed at a landscape scale, and will require a delivery system that is practical and economically viable. Understanding grey squirrel feeding behaviour is important so that delivery methods can be designed so that a sufficient number of target individuals receive an effective contraceptive dose at a time of year that will ensure their infertility throughout peak times of breeding. The main aims of this study were to assess how sex, season, squirrel density and bait point density influenced; (1) the probability of a squirrel visiting a feeder and (2) the amount of bait consumed from feeders. Field trials were conducted on six woodland populations of squirrels in three seasons, with four days of bait deployment via purpose-designed squirrel-specific bait hoppers with integrated PIT-tag readers. It was possible to deliver multiple doses on most days to most male and female grey squirrels, with bait deployment more likely to be effective in spring, immediately before the second annual peak in squirrel breeding, followed by winter, immediately before the first peak in breeding. The results from this study could be used to design methods for delivering oral contraceptive baits to grey squirrels in the future and the methods used could be applied to other small mammal species and other bait delivery systems. © 2024 Crown copyright and The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. This article is published with the permission of the Controller of HMSO and the King's Printer for Scotland.
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Affiliation(s)
- Sarah E Beatham
- National Wildlife Management Centre, APHA, York, UK
- Conservation Ecology Group, Department of Biosciences, Durham University, Durham, UK
| | - Philip A Stephens
- Conservation Ecology Group, Department of Biosciences, Durham University, Durham, UK
| | | | - Julia Coats
- National Wildlife Management Centre, APHA, York, UK
| | - Erin Thomas
- National Wildlife Management Centre, APHA, York, UK
| | | | - Giovanna Massei
- Botstiber Institute for Wildlife Fertility Control, Department of Environment and Geography, University of York, York, UK
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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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Liu M, Ren D, Wan X, Shen X, Zhao C, Xingan, Wang Y, Bu F, Liu W, Zhang Z, Gao Y, Si X, Bai D, Yuan S, Zheng F, Wan X, Fu H, Wu X, Zheng A, Liu Q, Zhang Z. Synergistic effects of EP-1 and ivermectin mixture (iEP-1) to control rodents and their ectoparasites. PEST MANAGEMENT SCIENCE 2023; 79:607-615. [PMID: 36214760 DOI: 10.1002/ps.7226] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 09/23/2022] [Accepted: 10/10/2022] [Indexed: 06/16/2023]
Abstract
BACKGROUND Ectoparasites of rodents play significant roles in disease transmission to humans. Conventional poisoning potentially reduces the population densities of rodents, however, they may increase the ectoparasite loads on the surviving hosts. EP-1 has been shown to have anti-fertility effects on many rodent species, while ivermectin is effective in controlling ectoparasites. In this study, we examined the combined effects of EP-1 and ivermectin mixture (iEP-1) baits on rodents and their corresponding flea/tick loads. RESULTS In males, the weight of testis, epididymis, and seminiferous vesicle were reduced to less than 33%, 25%, and 17%, respectively, compared to the control group following administration of iEP-1 for 7 days. The weight of the uterus increased by approximately 75%. After 5 days of iEP-1 intake, all ticks were killed, whereas 94% of fleas on mice died after 3 days of bait intake. In the field test near Beijing, the flea index was reduced by more than 90% after 7 days of iEP-1 bait delivery. In a field test in Inner Mongolia, the weights of testis, epididymis, and seminiferous vesicle were significantly reduced by 27%, 32%, and 57%, respectively, 2 weeks after iEP-1 bait delivery. Approximately 36% rodents exhibited obvious uterine oedema accompanied by a weight increase of about 150%. The flea index was reduced by over 90%. CONCLUSION Our results indicated that iEP-1 is a promising treatment for reducing the abundance of both small rodents and their ectoparasites; this will be effective for managing rodent damage and transmission of rodent-borne diseases associated with fleas and ticks. © 2022 Society of Chemical Industry.
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Affiliation(s)
- Ming Liu
- State Key Laboratory of Integrated Pest Management, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Dongsheng Ren
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Xinrong Wan
- State Key Laboratory of Integrated Pest Management, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Xiaona Shen
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Chaoyue Zhao
- State Key Laboratory of Integrated Pest Management, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Xingan
- Inner Mongolia Agriculture University, Hohhot, Inner Mongolia, China
| | - Yujie Wang
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Fan Bu
- Center of Disease Control & Prevention of Inner Mongolia, Hohhot, Inner Mongolia, China
| | - Wei Liu
- State Key Laboratory of Integrated Pest Management, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Zhongbing Zhang
- Inner Mongolia Minzu University, Tongliao, Inner Mongolia, China
| | - Yulong Gao
- Inner Mongolia Minzu University, Tongliao, Inner Mongolia, China
| | - Xiaoyan Si
- Inner Mongolia Minzu University, Tongliao, Inner Mongolia, China
| | - Defeng Bai
- State Key Laboratory of Integrated Pest Management, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- Ordos Municipal Center for Disease Control and Prevention, Ordos, China
| | - Shuai Yuan
- Center of Disease Control & Prevention of Inner Mongolia, Hohhot, Inner Mongolia, China
| | - Feng Zheng
- International Society of Zoological Sciences, Beijing, China
| | - Xinru Wan
- State Key Laboratory of Integrated Pest Management, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Heping Fu
- Center of Disease Control & Prevention of Inner Mongolia, Hohhot, Inner Mongolia, China
| | - Xiaodong Wu
- Center of Disease Control & Prevention of Inner Mongolia, Hohhot, Inner Mongolia, China
| | - Aihua Zheng
- State Key Laboratory of Integrated Pest Management, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Qiyong Liu
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Zhibin Zhang
- State Key Laboratory of Integrated Pest Management, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- Ordos Municipal Center for Disease Control and Prevention, Ordos, China
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