Reproductive ecology of the black rat (Rattus rattus) in Madagascar: the influence of density-dependent and -independent effects

The black rat(Rattus rattus)poses a severe threat to food security and public health in Madagascar,where it is a major cause of pre-and post-harvest crop losses and an important reservoir for many zoonotic diseases,including plague.Elsewhere,ecologically based rodent management(EBRM)strategies have been developed using ecologi-cal information to inform decisions on where and when to target control.EBRM could deliver improved health and well-being outcomes in Madagascar if adapted to the local ecological context.Using data collected from removal studies,we explored spatio-temporal patterns in the breeding activity of the black rat(R.rattus)in domestic and agricultural habitats across Madagascar and investigated to what extent these trends are influenced by rainfall and rat density.We identified clear spatio-temporal variation in the seasonality of R.rattus reproduction.Reproduction was highly seasonal both inside and outside of houses,but seasonal trends varied between these two habitats.Sea-sonal trends were explained,in part,by variation in rainfall;however,the effect of rainfall on reproductive rates did itself vary by season and habitat type.A decline in breeding intensity with increasing rat density was recorded outside of houses.This has important implications for control,as populations may compensate for removal through increased reproduction.We recommend that sustained control initiated before the main breeding season,combined with improved hygiene and adequate rodent-proofing in homes and grain stores,could curtail population growth and reduce pre-and post-harvest losses provided that these measures overcome the compensatory response of rodent populations.

Comparative assessment on rodent impacts and cultural perceptions of ecologically based rodent management in 3 Afro-Malagasy farming regions

Rodents generate negative consequences for smallholder farmers in Africa that directly impact household and livestock damage,food security,and public health.Ecologically Based Rodent Management(EBRM)seeks sustainable solutions for the mitigation of rodent damage through assessments of rodent population dynamics,agro-ecosystems,and socio-cultural contexts.We adopt a comparative approach across 3 rural Afro-Malagasy smallholder farming regions in South Africa,Tanzania,and Madagascar to assess the household impacts of rodent pests and current perceptions and preferences associated with several rodent control measures.We conducted focus group questionnaires and interviews in different study site locations.Rodents assert multiple impacts on Afro-Malagasy farmers demonstrating recurrent and emerging agricultural and household costs,and public health impacts.We identify a significant knowledge gap in educating communities about the application of different EBRM approaches in favor of acute poisons that are perceived to be more effective.Cultural issues and taboos also have a significant impact on the social acceptance of rodent hunting as well as biological control using indigenous predators.We advocate for an enhanced investigation of the socio-cultural beliefs associated with different rodent practices to understand the factors underlying social acceptance.A collaborative approach that integrates the perspectives of target communities to inform the design of EBRM initiatives according to the specific agro-ecosystem and socio-cultural context is necessary to ensure programmatic success.