Graph and circuit theory connectivity models of conservation biological control agents.

نویسندگان

  • Insu Koh
  • Helen I Rowe
  • Jeffrey D Holland
چکیده

The control of agricultural pests is an important ecosystem service provided by predacious insects. In Midwestern USA, areas of remnant tallgrass prairie and prairie restorations may serve as relatively undisturbed sources of natural predators, and smaller areas of non-crop habitats such as seminatural areas and conservation plantings (CP) may serve as stepping stones across landscapes dominated by intensive agriculture. However, little is known about the flow of beneficial insects across large habitat networks. We measured abundance of soybean aphids and predators in 15 CP and adjacent soybean fields. We tested two hypotheses: (1) landscape connectivity enhances the flow of beneficial insects; and (2) prairies act as a source of sustaining populations of beneficial insects in well-connected habitats, by using adaptations of graph and circuit theory, respectively. For graph connectivity, incoming fluxes to the 15 CP from connected habitats were measured using an area- and distance-weighted flux metric with a range of negative exponential dispersal kernels. Distance was weighted by the percentage of seminatural area within ellipse-shaped landscapes, the shape of which was determined with correlated random walks. For circuit connectivity, effective conductance from the prairie to the individual 15 CP was measured by regarding the flux as conductance in a circuit. We used these two connectivity measures to predict the abundance of natural enemies in the selected sites. The most abundant predators were Anthocoridae, followed by exotic Coccinellidae, and native Coccinellidae. Predator abundances were explained well by aphid abundance. However, only native Coccinellidae were influenced by the flux and conductance. Interestingly, exotic Coccinellidae were negatively related to the flux, and native Coccinellidae were highly influenced by the interaction between exotic Coccinellidae and aphids. Our area- and distance-weighted flux and the conductance variables showed better fit to field data than area-weighted flux or Euclidean distance from the prairie. These results indicate that the network of seminatural areas has greater influence on the flow of native predators than that of exotic predators, and that the prairie acts as a source for native Coccinellidae. Managers can enhance conservation biocontrol and sustain the diversity of natural enemies by optimizing habitat networks.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Assessment of Landscape Connectivity and Prediction of Migration Corridors for the Baluchistan Black Bear (Ursus thibetanus gedrosianus Blanford, 1877) in the Southeastern Habitats, Iran

The Baluchistan Black Bear (BBB), a critically endangered subspecies (CR), is distributed in the southeastern Iran. Modelling of landscape connectivity of the BBBs among habitat patches can be insightful for the conservation managers working in Iran. Our study was designed to identify the potential corridors among 31 habitat patches of the BBBs in Iran using the circuit theory method. Habitat s...

متن کامل

استفاده از تئوری مدارهای الکتریکی جهت شناسایی کریدورهای مهاجرتی بین پناهگاه‌های حیات وحش موته و قمشلو در استان اصفهان

Modeling of ecological connectivity across landscape is important for understanding a wide range of ecological processes. Modeling ecological connectivity between habitats and incorporating these models into conservation planning require quantifying the effect of spatial patterns of landscape on the degree of habitats connectivity. Recently, concepts from electrical circuit theory have been ad...

متن کامل

کاربرد تئوری گرف در مطالعات اکولوژی سیمای سرزمین نمونه موردی: سنجش پیوستگی زیستگاه‌های کلان‌شهر ملبورن

A new method to quantify, monitore and assess ecological structures and functions is the application of graph theory. In ecology, this theory demonstrates its suitable application in assessment of ecological connectivity. Connectivity is the structural attribute of landscape which facilitates the species movement among their habitats. Using graph theory, this paper aims to assess the connectivi...

متن کامل

Title: Using Circuit Theory to Model Connectivity in Ecology, Evolution, and Conservation

Connectivity among populations and habitats is important for a wide range of ecological processes. Understanding, preserving, and restoring connectivity in complex landscapes requires connectivity models and metrics that are reliable, efficient, and processbased. We introduce a new class of ecological connectivity models based in electrical circuit theory. Although they have been applied in oth...

متن کامل

ارزیابی پیوستگی اکولوژیک لکه‌های سبز شهری با استفاده از تئوری گراف،مطالعه موردی کلان‌شهر اهواز

Connectivity of urban green patches is an important structural attribute of urban landscape that facilitates the species movement and transfer of their genes among their habitats. So far, several methods including Graph Theory have been applied to assess ecological connectivity. This research was aimed  to study the application of graph theory to measure the connectivity of green patches in the...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:
  • Ecological applications : a publication of the Ecological Society of America

دوره 23 7  شماره 

صفحات  -

تاریخ انتشار 2013