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Seed and leaf extracts ofMammea americana (mamey apple) have a historical use as a biopesticide with the active components previously characterized. We reexamined the utility of this natural bioinsecticide in light of existing sources of material as a by-product of the fruit processing industry. Our results addDiabrotica virgifera virgifera andTrichoplusia ni to the list of insects which are susceptible to the insecticidal ingredients ofM. americana and confirms earlier reports of activity againstBlatella germanica, Periplaneta americana, andPlutella xylostella. We report LD5Os for crude hexane extracts ofM. americana leaves and seeds againstT. ni. These materials represent renewable sources of bioinsecticides for agriculture, and should regenerate interest in coumarin-type compounds for novel pesticidal action. 相似文献
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Torre J. Hovick Brady W. Allred Devan A. McGranahan Michael W. Palmer R. Dwayne Elmore Samuel D. Fuhlendorf 《Biodiversity and Conservation》2016,25(2):345-356
A species distribution combines the resources and climatic tolerances that allow an individual or population to persist. As these conditions change, one mechanism to maintain favorable resources is for an organism to shift its range. Much of the research examining range shifts has focused on dynamic distribution boundaries wheras the role of species breeding habitat or migration strategies on shift tendencies has received less attention. We expand on previous research by using a large suite of avian species (i.e., 277), analyzing observed abundance-weighted average latitudes, and categorizing species by breeding environment and migration strategy. We used the North American Breeding Bird Survey dataset to address two questions: (1) Has the center of observed abundance for individual species shifted latitudinally? (2) Is there a relationship between migration strategy or breeding habitat and range shifts? Results indicate the majority of species have experienced poleward range shifts over the last 43 years, and birds breeding in all habitat showed trends of poleward shift but only those species breeding in scrub-shrub and grassland environments were different from zero. Additionally, species that are short distance migrants are experiencing significant poleward shifts while Neotropical and permanent residents had shifts that were not different from zero. Our findings do support the general trend expected from climate driven changes (i.e., > 52 % shifting poleward), however, the proportion of species exhibiting equatorial shifts (24 %) or no significant shifts (23 %) illustrates the complex interplay between land cover, climate, species interactions, and other forces that can interact to influence breeding ranges over time. Regardless of the mechanisms driving range shifts, our findings emphasize the need for connecting and expanding habitats for those species experiencing range shifts. This research describes the patterns of breeding birds through central North America and we encourage future research to focus on the mechanisms driving these patterns. 相似文献
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The environmental texture hypothesis (ETH) proposes that the spatial geometry or texture of the environment influences the
rate at which species are accumulated in space or time. Specifically, the ETH suggests that regions, and spatial scales, that
exhibit a larger rate of environmental distance decay (DD) should exhibit more rapid rates of species turnover. The ETH should
apply over any range of scales where the environment is driving species distributions. To examine the relevance of the ETH
at local spatial scales, we tested for a positive relationship between the rate of change in soil chemical properties and
vascular plant species composition in grassland and woodland habitats. We recorded presence–absence data along a 1.883 km
transect in each habitat and estimated the rate of turnover and environmental DD for spatial lags of 1–41 m. We found that
the soil environment explained spatial patterns of species composition more accurately in the grassland habitat compared to
the woodland habitat. Consequently the rate of change in soil properties as a function of spatial distance was significantly
positively correlated with the rate of species turnover in the grassland but not the woodland. Our study suggests that one
of the central premises of the ETH is relevant for local patterns of species turnover if the environment appears to influence
species composition. 相似文献