Spatiotemporal stability of two beetle populations in non‐farmed habitats in an agricultural landscape

Abstract

Summary 1.Understanding the spatiotemporal ecology of invertebrates in agricultural ecosystems is important for developing management strategies to enhance biodiversity and reduce pesticide use. There is increasing recognition that studies need to be undertaken at scales larger than the field but the ability to do this is often resource limited. Pheromone traps, developed for pest management, can provide a relatively cheap means of collecting data across wide geographical scales. In this study we used such traps to examine the spatial stability of two species of agrioted beetles in non-farmed habitats over a period of 3 years. The spatial distributions of adult male Agriotes lineatus and Agriotes obscuruswere sampled from April until July at a number of sites across 950 ha on Westham Island, British Columbia, Canada. Data were assembled as spatially referenced cumulative trap counts by species and year, and analysed for evidence of aggregation and clustering using spatial analysis by distance indices (SADIE) methodology. Both intraspecific and interspecific association analyses were then carried out. A further set of analyses considered the spatial associations between different sampling dates in 2004. 3. Agriotes lineatus was clustered into patches and gaps at the landscape scale in all 3 years, and A. obscurus showed similar spatial structure in 2002 and 2003. For both species, spatiotemporal stability at the landscape scale was evident. There was also a positive association between the two species in 2 out of the 3 years, suggesting that they were responding in a similar manner to the landscape environment. 4. Synthesis and applications . This study showed that there was substantial temporal stability in the spatial structures of A. lineatus and A. obscurus in non-farmed habitats, and that the two species respond in a broadly similar way to a heterogeneous agricultural landscape. This suggests that models to predict distributions within a landscape could be developed to guide decisions about where to grow vulnerable crops. Identification of the environmental factors that differentiate between clusters and gaps in their spatial distributions may also make it possible to manipulate populations and reduce their impact as pests without recourse to insecticides. Moreover, our results extend the spatial scales over which SADIE statistics have been used, and demonstrate the usefulness of pheromone trapping as a sampling method in addressing ecological questions at a landscape scale.

Multiscale approach to pest insect monitoring: Random walks, pattern formation, synchronization, and networks

“…The example of aphids considered above is therefore by no means unique. There is increasing recognition that an efficient and reliable insect pest monitoring program should include consideration of scales larger than a single field scale as the importance of long-distance cross-correlations between the pest abundance in different fields has become evident [15,21,22].…”

Uso da geoestatística para caracterização da distribuição espacial de larvas de Diloboderus abderus

“…Dentre essas, a geoestatística (ELLSBURY et al, 1998;FARIAS et al, 2004;BLACKSHAW & VERNON, 2006;FARIAS et al, 2008), que se fundamenta no princípio de que a diferença no valor de uma dada variável, em dois pontos, é dependente da distância entre esses, estando associada às técnicas usadas para analisar e inferir valores de uma variável distribuída no espaço e/ ou no tempo (GARCÍA, 2006). O trabalho teve por objetivo utilizar técnicas geoestatísticas para analisar a distribuição espacial de larvas de D. abderus em lavouras no Estado do Rio Grande do Sul.…”

Migration of coccinellids to alfalfa fields with varying adjacent vegetation in Central Chile

“…There is an increasing awareness that in agricultural landscapes non-farmed areas surrounding crops are an essential part of crop habitats (Holland et al, 2005;Blackshaw and Vernon, 2006). They are composed by different types of habitat such as forests, hedgerows, field margins, fallows and meadows, which are temporally more stable and heterogeneous environments than annual, arable crops (Tscharntke et al, 2007).…”