Abundance of insects and aerial insectivorous birds in relation to pesticide and fertilizer use

Background:The abundance of insects has decreased considerably during recent decades,resulting in current abundance showing 70-80%reductions in more than 15 studies across temperate climate zones.Dramatic reduc-tions in the abundance of insects are likely to have consequences for other taxa at higher trophic levels such as preda-tors and parasites.Pesticides,fertilizers and agricultural land use are likely candidates accounting for such reductions in the abundance of insects.Methods:Here we surveyed the abundance of flying insects,and the reduction in the abundance of insects as a consequence of intensive reduction in agricultural practice linked to fertilizer use and pesticide use.Finally we dem-onstrated consistency in abundance of birds among study sites.Results:We demonstrated that the use of fertilizers and pesticides had reduced the abundance of insects,with consequences for the abundance of insectivorous bird species such as Barn Swallows(Hirundo rustica),House Martins(Delichon urbicum)and Swifts(Apus apus).Juvenile Barn Swallows were negatively affected by the reduced abundance of insects and hence the reproductive success of insectivorous bird species.These effects imply that the abundance of insects could be reduced by the availability of insect food.Conclusions:These effects of intensive agriculture on insect food abundance are likely to have negative impacts on populations of insects and their avian predators.This hypothesis was validated by a reduction in the abundance of insects,linked to an increase in the abundance of fertilizers and a general change in farming practice.

Comparative analysis of the intestinal tract microbiota and feeding habits of five sympatric flycatchers

Gut microbiota and host interactions co-evolve and develop into stably adapted microbial communities and play vital roles in maintaining the health of organisms.Diet is supposed to be an important driver of differences in gut microbiota,but previous studies would commonly use literature depictions,which are essential but inaccurate,to explain the effects of diet on the gut microbiota of wild birds.In this study,we collected intestinal samples from five sympatric flycatchers to compare the gut microbial differences using bacterial 16S rRNA genes from Illumina MiSeq platform.Over 1,642,482 quality-filtered sequences from 1816S rRNA libraries were obtained and distinct compositions and diversities of gut microbiota were found in five flycatchers.Their gut microbiota is mainly from the four bacterial phyla of Proteobacteria,Firmicutes,Actinomycetes,and Bacteroidetes,but at the genus level showed a significant difference.Functional predictions revealed that the metabolic capacity of the gut microbiota of five flycatchers is greatly distinguished at KEGG level 3.And multiple food fragments showed a significant correlation with gut microbiota.Besides,the significant differences in the specific composition of the diets of the five insectivorous flycatchers indicated the differentiation of dietary niches.The study of the gut microbiota and feeding habits of sympatric flycatchers would increase the understanding of the gut microbial diversity of wild birds,and also improve our cognition of the co-evolution and co-adaptation within the host gut microbiota relations.

Antennal epicuticular structure of camel crickets (Orthoptera: Rhaphidophoridae) for identifying the prey of Mustella sibrica Pallas

Camel crickets (Orthoptera: Rhaphidophoridae) are a group of wingless and humpbacked Orthopteran insects. They are closed relatives to katydids and crickets;they were called spider crickets somewhere because of their long legs. Camel cricket plays an important role in the food web in various ecosystems. In the forest ecosystem, they live in the ground level of forestry under litters and fallen leaves, and some of them live beneath the log and hid themselves under loosen tree barks. They feed on decomposing organic substances and serve as decomposers in the food chain. It is a very common insect prey to insectivorous animals in natural and artificial vegetation. Guandaushi (GDS) is the experimental forest station of National Chung Hsing University, as the study site of long term ecological research (LTER) in Taiwan. And the camel cricket became an important subject and a dominant insect group in the LTER studies. They are the major parts of the insect preys of vertebrates, especially to the insectivorous mammals. According to our previous publication, 32.2% of the insect preys of Mustela sibirica Pallas are camel crickets in GDS forest ecosystem. There were 5 morpho-species of camel crickets by the characters of antennal epicuticular characters. The camel cricket was collected from various ways according to the LTER study during 1995-1998. The morphology of antennal epicuticular structure from totally 60 individuals was observed by using SEM. The epicuticular sculpture was described and classified into Type I and Type II by the SEM photographs. Type I has 8 patterns and Type II has 5 patterns in this study. The illustration and the pictorial key were provided here as the tool for further application. The morpho-species could not be identified due to the remainder being fragmented while examined. After the study, the SEM antennal epicuticular structures were classified and identified based upon the antennae sample of the morphospecies from the specimens of the 5 camel crickets which were collected from GDS forest ecosystem in this study. This is a part of the fundamental study for the protocol of ecosystem study. The protocol for identifying the insectivorous animal’s prey by the insect fragment of food remainders is necessary. One more, there were 7 of the 13 patterns of antennal epicuticular structure applied to analysis the 5 morpho-species provided as the case study for taxonomy.

Invertebrates Diversity in Arabuko-Sokoke Forest and Nearby Farm­land at Gede,Kilifi County,Kenya

Insectivorous bats mainly feed on various types of invertebrates.The authors studied the abundance and diversity of invertebrates in the farmland in the eastern part of Arabuko-Sokoke Forest,mainly to assess their availability to insectivorous bats occurring in the two study sites.Solar powered light traps were used to attract aerial invertebrates to a white suspended cloth sheet used as a landing surface.The sampling was conducted for four hours in one trapping station each night,and in twelve different stations both in the ASF and farmland.A total of 6,557 invertebrates individuals were trapped,which included 48%in ASF and 52%in the farmland.The two most common invertebrate orders were Hymenoptera(ants,bees,wasps and sawflies)represented by 38.1%,and Coleoptera(beetles,28.1%).The interior of ASF had higher invertebrate species diversity(Shannon-Weiner index 1.72±0.1),than the farmland(1.41±0.1).Although the farmland(260.5±52.9,N=12)had higher mean number of invertebrates trapped per night,than the interior of ASF(200.3±36.4,N=12),there was no significant difference between the medians of invertebrates captured in the two study areas(Mann-Whitney U-Test,U=61:P>0.544).Thus,the farmland and the interior of ASF had the same invertebrate abundance.This study indicates the value of human-modified areas(agricultural and human settlements)landscapes,always ignored in biodiversity surveys,in sustaining diverse invertebrates that are preyed by different species of insectivorous bats that occur in the two study areas.

Natural enemies depend on remnant habitat size in agricultural landscapes

In recent decades,the consequences of habitat fragmentation have been of growing concern,because it is particularly important to understand how fragmentation may affect biodiversity,an ecological service.We tested two hypotheses：（1） that natural fragment size in agricultural landscapes indirectly affects the herbivore through effects on natural predator populations;and（2） predator activity into the crop reduces along the distance from the natural fragment edge.From 2008 and 2009,we conducted our study in seven forest remnants and in surrounding coffee plantations（fragments ranged from 6 to 105 ha,mean 49.28 ± 36.60 ha） in Southern Minas Gerais,Brazil.Birds were sampled by point counts,and insect predation was evaluated by using an artificial insect model（Koh and Menge 2006）.Our results suggest that although there were many potential predators（e.g.,wasps,ants,birds,and mammals）,birds were the most important taxon unit.The covariance analysis supported the hypothesis that patch size affected the number of larvae predation by overall taxi,but there was no support for a distance effect.These findings suggest that natural enemies’ ecological service（mainly from birds） declined with remnant reduction,which has implications not only for human welfare,but also in strengthening the economic justifications for conserving the remaining natural habitats and biodiversity in agricultural landscapes.

Identification and investigation of Calodium hepaticum in rodents and insectivores from Wuhan section of the Yangtze River in China

Objective:To investigate the prevalence of Calodium hepaticum(C.hepaticum)in rodents and insectivores from Wuhan section of the Yangtze River in China,and to provide evidence for the prevention and treatment of hepatic Calodium infection.Methods:Rodents and insectivores were captured from three selected Yangtze River beaches using mousetraps.The three survey sites were divided into six areas according to natural conditions,with 60 mousetraps placed in each area.The liver lesions in the captured rodents were observed by the naked eye and the eggs in the liver tissue were observed by microscopic examination.Results:A total of 1080 mousetraps were placed,and 1075 mousetraps were retrieved,with the retrieve rate as 99.5%.A total of 101 Apodemus agrarius,12 Rattus norvegicus,and 9 Crocidura attenuata were caught.The average density of rodents and insectivores was 10.5%and 0.8%,respectively.DNA of egg nodules from infected rodents showed 98%similarity with that of C.hepaticum 18 S rRNA(LC425008.1).One Rattus norvegicus was infected with C.hepaticum,with an infection rate of 3.23%in the Erqi river beach;the other two beaches did not show the incidence of C.hepaticum.Conclusions:The monitoring of C.hepaticum in the Yangtze River beaches should be strengthened to reduce the risk of human C.hepaticum infection.

Food Habits of <i>Bryconaethiops boulengeri </i>Pellegrin, 1900 (Characiformes: Alestidae) of Djiri River Tributary of the Right Bank of Congo River

Diet of 300 specimens of Bryconaethiops boulengeri from Djiri River (Congo Brazzaville) caught with cash nets was studied according to the size of fish, sampling stations and hydrological season. Sampling focused on twelve annual withdrawals made during three years. The relative importance index combining numerical and weight percentages of occurrence was calculated and also the sex ratio was evaluated. Bryconaethiops boulengeri consumes terrestrial and aquatic insects and everything that falls into the water (birds feathers, plant debris, fruits, etc.). The percentage of emptiness is 9.66% of the three sampling stations selected;no significant difference in diet was observed whatever the season.

Occupancy of avian foraging guilds in soybean fields and borders in Entre Ríos, Argentina: responses to vegetation structure and prey resources

Background:Reconciling agriculture and biodiversity conservation is a challenge given the growing demand for agricultural products.In recent decades,Argentina has witnessed agricultural expansion and intensification affecting biodiversity and associated ecosystem services.Within agroecosystems,the level of habitat quality is critical for birds,and may depend on vegetation structure,availability of invertebrate prey,and the use of pesticides.Although the relationship between vegetation structure and avian occurrence has been widely studied,to our knowledge,there are no studies that also incorporate prey availability throughout the cycle of soybean crops in Argentina.We estimated and predicted the effects of land cover and temporal variation on the occurrence of avian foraging guilds in Entre Ríos,Argentina,in order to guide management related to potential ecosystem services provided by birds.We also estimated temporal effects of vegetation structure and insecticides on the main arthropod orders consumed by birds to evaluate prey availability.Methods:We conducted bird and arthropod surveys for 2 years along transects located in 20 randomly selected soybean fields(N=60)and their adjacent borders(N=78)throughout the crop growing season,in four seasons.We estimated avian occupancy,accounting for imperfect detection,and arthropod counts fitting generalized linear mixed models.Results:The number of native trees in field borders positively influenced the occurrence of most bird species,mainly insectivores.Granivore foliage gleaners,also were positively affected by grass height.Salliers and aerial foragers were weakly affected by distance to forest and native trees.In general,the availability of invertebrates to birds was highest during the third season.Arthropod counts in borders were greater during the last three crop stages than during the pre-sowing period.Conclusions:We found that with 10 to 15 native tree species in borders,coupled with a complex vegetation structure with shrubs and grasses,we could conserve a wide spectrum of insectivorous birds,and may contribute to the invertebrate pest control service.Vegetated field borders function as a refuge for arthropods,especially agriculturally beneficial taxa such as Hymenopterans.Finally,several groups of birds use the interior of the fields and could help control pests.

High-throughput sequencing reveals dietary segregation in Malaysian babblers

The coexistence of numerous species within a community results from how those species use available resources.Babblers are one of the major groups of Malaysian insectivorous birds,which frequently forage in dense vegetation cover and have a high level of sympatry.Therefore,examining the diet,prey selection,and niche segregation of babblers can be challenging.In this study,we used high-throughput sequencing to investigate potential dietary overlap or segregation among 10 babbler species of the 4 genera of the family Pellorneidae and Timaliidae:Pellorneum,Malacopteron,Stachyris,and Cyanoderma in central peninsular Malaysia.We tested the hypothesis that trophically similar species may differ in resource use to avoid competitive exclusion.We identified 81 distinct arthropod taxa from fecal samples,belonging to 71 families representing 13 orders,which were predominantly from 16 dipteran,13 lepidopteran,and 10 coleopteran families.Of all the prey taxa consumed,45%were found to be distinct across the 10 babbler species,and<35%were shared simultaneously by≥3 babbler species,indicating minimal dietary overlap.The black-throated babbler Stachyris nigricollis and moustached babbler Malacopteron magnirostre had the most generalist tendencies because they consumed a greater variety of prey taxa.Small dietary overlap values(Ojk)and a relatively wide range of food resources suggest that dietary segregation occurred among the studied babblers.The great diversity of prey consumed revealed the presence of dietary flexibility among the sympatric insectivorous birds,thus reducing any active dietary competition and facilitating the coexistence through niche partitioning.