The pattern of plague endemicity in Tanzania is characterized by continuous re-appearance of the disease in some locations, while in other neighbouring villages the disease has never or seldom been observed. To unders...The pattern of plague endemicity in Tanzania is characterized by continuous re-appearance of the disease in some locations, while in other neighbouring villages the disease has never or seldom been observed. To understand the reasons for this pattern, we studied small mammal and flea species composition, diversity and relative abundances in two plague-endemic and two plague-free locations. We asked （a） whether fleas more abundant in plague-endemic locations differ in their characteristic abundance and the degree of their host specificity from fleas more abundant in plague-free locations and （b） whether hosts most abundant in p/ague-endemic locations differ in the diversity of their flea assemblages from hosts most abundant in p/ague-free locations. We characterized （a） each host species by species richness and degree of taxonomic relatedness of its flea assemblages and （b） each flea species by its mean abundance and size, and degree of taxonomic relatedness of its host spectrum and compared their relative abundances between locations. No significant difference between plague-endemic and plague-free locations in either host density or any variable related to flea abundance or diversity was found. However, there was marginally significant effect of taxonomic distinctness of a flea assemblage barboured by a host on its probability to be more abundant in either plague-endemic or plague-free locations. Furthermore, hosts more abundant in plague-endemic locations tended to harbour closely-related fleas. Finally, while opportunistic and specialist fleas were equally distributed in both sets of locations, fleas exploiting distantly-related hosts were found mainly in plague-free locations during the rainy season. We suggest that the observed patterns might arise due to seasonal and spatial differences in local microclimatic conditions and landscape connectivity [ Current Zoology 55 （3） ： 200 - 211, 2009].展开更多
Mango in Ghana is targeted as the next non-traditional export crop that is expected to fetch the highest foreign exchange for the country than cocoa. However, production and export constraints caused by fruit fly Bact...Mango in Ghana is targeted as the next non-traditional export crop that is expected to fetch the highest foreign exchange for the country than cocoa. However, production and export constraints caused by fruit fly Bactrocera invadens has placed serious limitation on its marketing to the extent of imposing bans on imports from Ghana. Notwithstanding efforts rolled out to control the flies, they are still prevalent in the system. This paper presents the cost benefit assessments of using ＂Biotechnology and Nuclear Agriculture Research Institute （BNARI） protein bait＂ to control fruit fly Bactrocera invadens relative to other control measures in the Eastern region of South Ghana. Scientists from the BNARI of the Ghana Atomic Energy Commission developed a research programme against this foe. Cost benefit assessment revealed that chemical control reduce losses from 60% to 40% at the beginning of the growing season and can reach up to 60% for late maturing varieties at a cost of US$915.2 per acre per year. However, with the BNARI trap, losses are reduced from 60% to 5% at the beginning of the growing season and can reach up to 10% for later maturing varieties at a cost of US$688 per acre per year. Using BNARI protein baits to control fruit fly also provide growers with benefits such as improved quality and shelf life for fruit because it is not subject to chemical treatments. The casual loop diagram （CLD） revealed that fly control with BNARI trap is friendly to beneficial insects during pollination and has no harmful impact on health compared to the traditional approaches.展开更多
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 ...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.展开更多
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...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 thefirst 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.展开更多
The lesser pouched rat,Beamys hindei,is a small rodent that is patchily distributed in the Eastern Arc Mountains and coastal forests in East Africa.The ecology of this species and its current distribution in coastal f...The lesser pouched rat,Beamys hindei,is a small rodent that is patchily distributed in the Eastern Arc Mountains and coastal forests in East Africa.The ecology of this species and its current distribution in coastal forests is not well known.Therefore,we conducted a study in selected coastal forests to assess the current distribution of the species and to investigate the population ecology in terms of abundance fluctuations and demographic patterns.Assessments of the species distribution were conducted in 5 forests through trapping with Sherman live traps.Data on ecology were obtained from monthly capture–mark–recapture studies conducted for 5 consecutive nights per month in two 1 ha grids set in Zaraninge Forest over a 2-year period.The results indicate the presence of B.hindei in 3 forests where it was not previously recorded.The population abundance estimates ranged from 1 to 40 animals per month,with high numbers recorded during rainy seasons.Reproduction patterns and sex ratios did not differ between months.Survival estimates were not influenced by season,and recruitment was low,with growth rate estimates of 1 animal per month.These estimates suggest a stable population of B.hindei in Zaraninge Forest.Further studies are recommended to establish the home range,diet and burrowing behavior of the species in coastal forests in East Africa.展开更多
Studies of populations of the multimammate rat Mastomys natalensis in Morogoro, Tanzania, show that soil textureappears to influence the population abundance and distribution of these rats in agricultural fields. The ...Studies of populations of the multimammate rat Mastomys natalensis in Morogoro, Tanzania, show that soil textureappears to influence the population abundance and distribution of these rats in agricultural fields. The lowest rodentpopulation abundance was found on sandy clay soils (F(2, 5) = 8.42;P = 0.025). The population abundances of M.natalensis on sandy clay loam and sandy loam soils did not differ significantly (P ≤ 0.05), possibly because thesesoils have a very similar texture. The results of this study suggest that M. natalensis prefers loam-textured soilswith a high percentage of sand, which are probably better than clay soils for burrowing and nesting, particularly inthe rainy season. The lower preference for clay soils is probably related to the poor aeration in these soils and thewaterlogging that occurs during the wet season.展开更多
We investigated host and flea species composition across different habitats during dry and rainy seasons in the Western Usambara Mountains in Tanzania.During both seasons,similarity in flea species composition increas...We investigated host and flea species composition across different habitats during dry and rainy seasons in the Western Usambara Mountains in Tanzania.During both seasons,similarity in flea species composition increased with an increase in the similarity in host species composition.Nevertheless,between-season within-habitat as well as within-season between-habitat similarity in host species composition was higher than similarity in flea species composition.Ordination of habitats according to their host and flea species composition demonstrated that the pattern of between-habitat similarity in both host and flea species composition varied seasonally.Despite the relatively rich mammal and flea fauna of the study region,the major contribution to variation in species composition between seasons and among habitats was due to a few species only.Flea assemblages on Lophuromys kilonzoi Verheyen et al.,2007 and Praomys delectorum Thomas,1910 in different habitats were equally similar in either season.In contrast,flea assemblages on Mastomys natalensis(Smith,1834)occurring in different habitats were more similar in the dry than in the rainy season,whereas the opposite was the case for fleas on Grammomys sp.In different hosts,the main differences in species composition of flea assemblages between seasons as well as among habitats were due to different flea species.Although our results support the earlier idea that parasite species composition is determined by both host species composition and habitat properties,the former appears to explain variance in flea species composition between localities in the tropics better than between localities in temperate and arid zones.展开更多
Consistent among individual variation in behavior,or animal personality,is present in a wide variety of species.This behavioral variation is maintained by both genetic and environmental factors.Parental effects are a ...Consistent among individual variation in behavior,or animal personality,is present in a wide variety of species.This behavioral variation is maintained by both genetic and environmental factors.Parental effects are a special case of environmental variation and are expected to evolve in populations experiencing large fluctuations in their environment.They represent a non-genetic pathway by which parents can transmit information to their offspring,by modulating their personality.While it is expected that parental effects contribute to the observed personality variation,this has rarely been studied in wild populations.We used the multimammate mouse Mastomys natalensis as a model system to investigate the potential effects of maternal personality on offspring behavior.We did this by repeatedly recording the behavior of individually housed juveniles which were born and raised in the lab from wild caught females.A linear correlation,between mother and offspring in behavior,would be expected when the personality is only affected by additive genetic variation,while a more complex relationship would suggests the presence of maternal effects.We found that the personality of the mother predicted the behavior of their offspring in a non-linear pattern.Exploration behavior of mother and offspring was positively correlated,but only for slow and average exploring mothers,while this correlation became negative for fast exploring mothers.This may suggests that early maternal effects could affect personality in juvenile M.natalensis,potentially due to density-dependent and negative frequency-dependent mechanisms,and therefore contribute to the maintenance of personality variation.展开更多
Seasonal abundance, reproductive biology and feeding ecology of the bushveld gerbil Tatera leucogaster (Peters,1852) were investigated in small-scale maize field–fallow land mosaics in south-western Tanzania. The ger...Seasonal abundance, reproductive biology and feeding ecology of the bushveld gerbil Tatera leucogaster (Peters,1852) were investigated in small-scale maize field–fallow land mosaics in south-western Tanzania. The gerbilswere collected over a 2-year period using Sherman live and Victor hold-fast snap traps in permanent 4.5-ha grids. Atotal of 664 individuals were captured over 13 650 trap nights, giving an overall trap success rate of 4.9%. Trapsuccess varied between seasons with and without crops in the field but not between habitat types. At this site, thebreeding activity of this species is seasonal. All individuals whose stomachs were analyzed ate a wide range ofitems, indicating omnivory in this species at this site;however, seeds were the most preferred diet category, with amean contribution of 50.4%, followed by arthropods, with a mean contribution of 25.7%. Other plant materialsbecame important during the very dry periods.展开更多
In this study we aimed to determine the relationship between sampling intensity and precision for estimating rodentdamage. We used the systematic row sampling technique to provide data to achieve precision and accurac...In this study we aimed to determine the relationship between sampling intensity and precision for estimating rodentdamage. We used the systematic row sampling technique to provide data to achieve precision and accuracy inestimations of rodent damage in maize fields at the planting and seedling stages. The actual rodent damage to maizein 15 fields, each 0.5 ha in size, in Morogoro, Tanzania, was established at the seedling stage. These data were usedto simulate the sampling intensities that would provide precision and accuracy. The variations between estimateswere plotted against the sampling intervals. The results of this study show that the relationship between averagestandardized variances and sampling intervals is linear. The heterogeneous distribution of damage in some plotscaused variations in the accuracy of the estimates between plots, but a sampling interval of five rows consistentlyproduced estimates with a variance of less than 10%. We provide a standard curve that will allow a decision to bemade on the sampling intensity as a function of required precision using the systematic row sampling technique inmaize fields.展开更多
Background:New insecticides with a novel mode of action such as neonicotinoids have recently been recommended for public health by WHO.Resistance monitoring of such novel insecticides requires a robust protocol to mon...Background:New insecticides with a novel mode of action such as neonicotinoids have recently been recommended for public health by WHO.Resistance monitoring of such novel insecticides requires a robust protocol to monitor the development of resistance in natural populations.In this study,we comparatively used three different solvents to assess the susceptibility of malaria vectors to neonicotinoids across Africa.Methods:Mosquitoes were collected from May to July 2021 from three agricultural settings in Cameroon(Njombe-Penja,Nkolondom,and Mangoum),the Democratic Republic of Congo(Ndjili-Brasserie),Ghana(Obuasi),and Uganda(Mayuge).Using the CDC bottle test,we compared the effect of three different solvents(ethanol,acetone,MERO)on the efficacy of neonicotinoids againstAnopheles gambiae s.l.In addition,TaqMan assays were used to genotype key pyrethroid-resistant markers inAn.gambiae and odds ratio based on Fisher exact test were used to evaluate potential cross-resistance between pyrethroids and clothianidin.Results:Lower mortality was observed when using absolute ethanol or acetone alone as solvent for clothianidin(11.4-51.9% mortality in Nkolondom,31.7-48.2% in Mangoum,34.6-56.1% in Mayuge,39.4-45.6% in Obuasi,83.7-89.3% in Congo and 71.1-95.9% in Njombe pendja)compared to acetone+MERO for which 100% mortality were observed for all the populations.Similar observations were done for imidacloprid and acetamiprid.Synergist assays(PBO,DEM and DEF)with clothianidin revealed a significant increase of mortality suggesting that metabolic resistance mechanisms are contributing to the reduced susceptibility.A negative association was observed between the L1014F-kdr mutation and clothianidin resistance with a greater frequency of homozygote resistant mosquitoes among the dead than among survivors(OR=0.5;P=0.02).However,the I114T-GSTe2 was in contrast significantly associated with a greater ability to survive clothianidin with a higher frequency of homozygote resistant among survivors than other genotypes(OR=2.10;P=0.013).Conclusions:This study revealed a contrasted susceptibility pattern depending on the solvents with ethanol/acetone resulting to lower mortality,thus possibly overestimating resistance,whereas the MERO consistently showed a greater efficacy of neonicotinoids but it could prevent to detect early resistance development.Therefore,we recommend monitoring the susceptibility using both acetone alone and acetone+MERO(4μg/ml for clothianidin)to capture the accurate resistance profile of the mosquito populations.展开更多
文摘The pattern of plague endemicity in Tanzania is characterized by continuous re-appearance of the disease in some locations, while in other neighbouring villages the disease has never or seldom been observed. To understand the reasons for this pattern, we studied small mammal and flea species composition, diversity and relative abundances in two plague-endemic and two plague-free locations. We asked （a） whether fleas more abundant in plague-endemic locations differ in their characteristic abundance and the degree of their host specificity from fleas more abundant in plague-free locations and （b） whether hosts most abundant in p/ague-endemic locations differ in the diversity of their flea assemblages from hosts most abundant in p/ague-free locations. We characterized （a） each host species by species richness and degree of taxonomic relatedness of its flea assemblages and （b） each flea species by its mean abundance and size, and degree of taxonomic relatedness of its host spectrum and compared their relative abundances between locations. No significant difference between plague-endemic and plague-free locations in either host density or any variable related to flea abundance or diversity was found. However, there was marginally significant effect of taxonomic distinctness of a flea assemblage barboured by a host on its probability to be more abundant in either plague-endemic or plague-free locations. Furthermore, hosts more abundant in plague-endemic locations tended to harbour closely-related fleas. Finally, while opportunistic and specialist fleas were equally distributed in both sets of locations, fleas exploiting distantly-related hosts were found mainly in plague-free locations during the rainy season. We suggest that the observed patterns might arise due to seasonal and spatial differences in local microclimatic conditions and landscape connectivity [ Current Zoology 55 （3） ： 200 - 211, 2009].
文摘Mango in Ghana is targeted as the next non-traditional export crop that is expected to fetch the highest foreign exchange for the country than cocoa. However, production and export constraints caused by fruit fly Bactrocera invadens has placed serious limitation on its marketing to the extent of imposing bans on imports from Ghana. Notwithstanding efforts rolled out to control the flies, they are still prevalent in the system. This paper presents the cost benefit assessments of using ＂Biotechnology and Nuclear Agriculture Research Institute （BNARI） protein bait＂ to control fruit fly Bactrocera invadens relative to other control measures in the Eastern region of South Ghana. Scientists from the BNARI of the Ghana Atomic Energy Commission developed a research programme against this foe. Cost benefit assessment revealed that chemical control reduce losses from 60% to 40% at the beginning of the growing season and can reach up to 60% for late maturing varieties at a cost of US$915.2 per acre per year. However, with the BNARI trap, losses are reduced from 60% to 5% at the beginning of the growing season and can reach up to 10% for later maturing varieties at a cost of US$688 per acre per year. Using BNARI protein baits to control fruit fly also provide growers with benefits such as improved quality and shelf life for fruit because it is not subject to chemical treatments. The casual loop diagram （CLD） revealed that fly control with BNARI trap is friendly to beneficial insects during pollination and has no harmful impact on health compared to the traditional approaches.
基金StopRats:European Union 9th European Development Fund grant from the African Caribbean and Pacific Science and Technology Programme(FED/2013/330-223)African Union(EcoRodMan:AURGII/1/006/2016)+5 种基金United Kingdom’s Department for International Development(AgriTT/894)SASOL Agricultural TrustSouth African National Research Foundation(LHS#88179)South African National Research Foundation and Department of Science and Technology through the South African Research Chair in Biodiversity Value and Change hosted by the University of Venda and co-hosted by the Centre for Invasion Biology,Stellenbosch University(NC,PT#87311)South African National Research Foundation(STW:UID 115040 and UID 107099)MEM also acknowledges the support of the Tanzania Commission for Science and Technology(COSTECH).
文摘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.
基金funded by the African Union/European Development Fund(EcoRodMan:AURGII/1/006/2016)support from the International Partnership Programme of the Chinese Academy of Sciences(Grant No.152111KYSB20160089)。
文摘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 thefirst 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.
基金This work was part of the Wildlife Population Ecology(WiPE)project under the Department of Wildlife Management at Sokoine University of Agriculture,supported by the Flemish VLIR-UOS Own Initiatives program.The authors acknowledge the cooperation from the Tanzania Wildlife Research Institute(TAWIRI)for providing permits to conduct the research in Saadani National Park,The Tanzania National Parks(TANAPA).We are especially grateful to the Saadani National Park staff,and Miss Halima Penga,the Park Ecologist for her assistance whenever needed.We appreciate the excellent field assistance from Omari Kibwana,Dege Hussein and Samwel Shaba and the commitment they extended during the whole study。
文摘The lesser pouched rat,Beamys hindei,is a small rodent that is patchily distributed in the Eastern Arc Mountains and coastal forests in East Africa.The ecology of this species and its current distribution in coastal forests is not well known.Therefore,we conducted a study in selected coastal forests to assess the current distribution of the species and to investigate the population ecology in terms of abundance fluctuations and demographic patterns.Assessments of the species distribution were conducted in 5 forests through trapping with Sherman live traps.Data on ecology were obtained from monthly capture–mark–recapture studies conducted for 5 consecutive nights per month in two 1 ha grids set in Zaraninge Forest over a 2-year period.The results indicate the presence of B.hindei in 3 forests where it was not previously recorded.The population abundance estimates ranged from 1 to 40 animals per month,with high numbers recorded during rainy seasons.Reproduction patterns and sex ratios did not differ between months.Survival estimates were not influenced by season,and recruitment was low,with growth rate estimates of 1 animal per month.These estimates suggest a stable population of B.hindei in Zaraninge Forest.Further studies are recommended to establish the home range,diet and burrowing behavior of the species in coastal forests in East Africa.
文摘Studies of populations of the multimammate rat Mastomys natalensis in Morogoro, Tanzania, show that soil textureappears to influence the population abundance and distribution of these rats in agricultural fields. The lowest rodentpopulation abundance was found on sandy clay soils (F(2, 5) = 8.42;P = 0.025). The population abundances of M.natalensis on sandy clay loam and sandy loam soils did not differ significantly (P ≤ 0.05), possibly because thesesoils have a very similar texture. The results of this study suggest that M. natalensis prefers loam-textured soilswith a high percentage of sand, which are probably better than clay soils for burrowing and nesting, particularly inthe rainy season. The lower preference for clay soils is probably related to the poor aeration in these soils and thewaterlogging that occurs during the wet season.
文摘We investigated host and flea species composition across different habitats during dry and rainy seasons in the Western Usambara Mountains in Tanzania.During both seasons,similarity in flea species composition increased with an increase in the similarity in host species composition.Nevertheless,between-season within-habitat as well as within-season between-habitat similarity in host species composition was higher than similarity in flea species composition.Ordination of habitats according to their host and flea species composition demonstrated that the pattern of between-habitat similarity in both host and flea species composition varied seasonally.Despite the relatively rich mammal and flea fauna of the study region,the major contribution to variation in species composition between seasons and among habitats was due to a few species only.Flea assemblages on Lophuromys kilonzoi Verheyen et al.,2007 and Praomys delectorum Thomas,1910 in different habitats were equally similar in either season.In contrast,flea assemblages on Mastomys natalensis(Smith,1834)occurring in different habitats were more similar in the dry than in the rainy season,whereas the opposite was the case for fleas on Grammomys sp.In different hosts,the main differences in species composition of flea assemblages between seasons as well as among habitats were due to different flea species.Although our results support the earlier idea that parasite species composition is determined by both host species composition and habitat properties,the former appears to explain variance in flea species composition between localities in the tropics better than between localities in temperate and arid zones.
基金B.V.B.was funded by the Ph.D.fellowship from the Research Foundation Flanders(FWO)(grant ID:11A0817N).
文摘Consistent among individual variation in behavior,or animal personality,is present in a wide variety of species.This behavioral variation is maintained by both genetic and environmental factors.Parental effects are a special case of environmental variation and are expected to evolve in populations experiencing large fluctuations in their environment.They represent a non-genetic pathway by which parents can transmit information to their offspring,by modulating their personality.While it is expected that parental effects contribute to the observed personality variation,this has rarely been studied in wild populations.We used the multimammate mouse Mastomys natalensis as a model system to investigate the potential effects of maternal personality on offspring behavior.We did this by repeatedly recording the behavior of individually housed juveniles which were born and raised in the lab from wild caught females.A linear correlation,between mother and offspring in behavior,would be expected when the personality is only affected by additive genetic variation,while a more complex relationship would suggests the presence of maternal effects.We found that the personality of the mother predicted the behavior of their offspring in a non-linear pattern.Exploration behavior of mother and offspring was positively correlated,but only for slow and average exploring mothers,while this correlation became negative for fast exploring mothers.This may suggests that early maternal effects could affect personality in juvenile M.natalensis,potentially due to density-dependent and negative frequency-dependent mechanisms,and therefore contribute to the maintenance of personality variation.
文摘Seasonal abundance, reproductive biology and feeding ecology of the bushveld gerbil Tatera leucogaster (Peters,1852) were investigated in small-scale maize field–fallow land mosaics in south-western Tanzania. The gerbilswere collected over a 2-year period using Sherman live and Victor hold-fast snap traps in permanent 4.5-ha grids. Atotal of 664 individuals were captured over 13 650 trap nights, giving an overall trap success rate of 4.9%. Trapsuccess varied between seasons with and without crops in the field but not between habitat types. At this site, thebreeding activity of this species is seasonal. All individuals whose stomachs were analyzed ate a wide range ofitems, indicating omnivory in this species at this site;however, seeds were the most preferred diet category, with amean contribution of 50.4%, followed by arthropods, with a mean contribution of 25.7%. Other plant materialsbecame important during the very dry periods.
文摘In this study we aimed to determine the relationship between sampling intensity and precision for estimating rodentdamage. We used the systematic row sampling technique to provide data to achieve precision and accuracy inestimations of rodent damage in maize fields at the planting and seedling stages. The actual rodent damage to maizein 15 fields, each 0.5 ha in size, in Morogoro, Tanzania, was established at the seedling stage. These data were usedto simulate the sampling intensities that would provide precision and accuracy. The variations between estimateswere plotted against the sampling intervals. The results of this study show that the relationship between averagestandardized variances and sampling intervals is linear. The heterogeneous distribution of damage in some plotscaused variations in the accuracy of the estimates between plots, but a sampling interval of five rows consistentlyproduced estimates with a variance of less than 10%. We provide a standard curve that will allow a decision to bemade on the sampling intensity as a function of required precision using the systematic row sampling technique inmaize fields.
文摘Background:New insecticides with a novel mode of action such as neonicotinoids have recently been recommended for public health by WHO.Resistance monitoring of such novel insecticides requires a robust protocol to monitor the development of resistance in natural populations.In this study,we comparatively used three different solvents to assess the susceptibility of malaria vectors to neonicotinoids across Africa.Methods:Mosquitoes were collected from May to July 2021 from three agricultural settings in Cameroon(Njombe-Penja,Nkolondom,and Mangoum),the Democratic Republic of Congo(Ndjili-Brasserie),Ghana(Obuasi),and Uganda(Mayuge).Using the CDC bottle test,we compared the effect of three different solvents(ethanol,acetone,MERO)on the efficacy of neonicotinoids againstAnopheles gambiae s.l.In addition,TaqMan assays were used to genotype key pyrethroid-resistant markers inAn.gambiae and odds ratio based on Fisher exact test were used to evaluate potential cross-resistance between pyrethroids and clothianidin.Results:Lower mortality was observed when using absolute ethanol or acetone alone as solvent for clothianidin(11.4-51.9% mortality in Nkolondom,31.7-48.2% in Mangoum,34.6-56.1% in Mayuge,39.4-45.6% in Obuasi,83.7-89.3% in Congo and 71.1-95.9% in Njombe pendja)compared to acetone+MERO for which 100% mortality were observed for all the populations.Similar observations were done for imidacloprid and acetamiprid.Synergist assays(PBO,DEM and DEF)with clothianidin revealed a significant increase of mortality suggesting that metabolic resistance mechanisms are contributing to the reduced susceptibility.A negative association was observed between the L1014F-kdr mutation and clothianidin resistance with a greater frequency of homozygote resistant mosquitoes among the dead than among survivors(OR=0.5;P=0.02).However,the I114T-GSTe2 was in contrast significantly associated with a greater ability to survive clothianidin with a higher frequency of homozygote resistant among survivors than other genotypes(OR=2.10;P=0.013).Conclusions:This study revealed a contrasted susceptibility pattern depending on the solvents with ethanol/acetone resulting to lower mortality,thus possibly overestimating resistance,whereas the MERO consistently showed a greater efficacy of neonicotinoids but it could prevent to detect early resistance development.Therefore,we recommend monitoring the susceptibility using both acetone alone and acetone+MERO(4μg/ml for clothianidin)to capture the accurate resistance profile of the mosquito populations.
