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Analysing the impact of trap shape and movement behaviour of ground-dwelling arthropods on trap efficiency

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journal contribution
posted on 24.07.2019, 13:51 by Danish A. Ahmed, Sergei V. Petrovskii
The most reliable estimates of the population abundance of ground-dwelling arthropods are obtained almost entirely through trap counts. Trap shape can be easily controlled by the researcher, commonly the same trap design is employed in all sites within a given study. Few researchers really try to compare abundances (numbers of collected individuals) between studies because these are heavily influenced by environmental conditions, e.g. temperature, habitat structure and food sources available, directly affecting insect movement activity. We propose that useful insights can be obtained from a theoretical-based approach. We focus on the interplay between trap shape (circle, square, slot), the underlying movement behaviour and the subsequent effect on captures. We simulate trap counts within these different geometries whilst considering movement processes with clear distinct properties, such as Brownian motion (BM), the correlated random walk (CRW) and the Lévy walk (LW). (a) We find that slot shaped traps are far less efficient than circular or square traps assuming same perimeter length, with differences which can exceed more than two-fold. Such impacts of trap geometry are only realized if insect mobility is sufficiently large, which is known to significantly vary depending on type of habitat. (b) If the movement pattern incorporates localized forward persistence then trap counts accumulate at a much slower rate, and this rate decreases further with higher persistency. (c) If the movement behaviour is of Lévy type, then fastest catch rates are recorded in the case of circular trap, and the slowest for the slot trap, indicating that trap counts can strongly depend on trap shape. Lévy walks exacerbate the impact of geometry while CRW make these differences more inconsequential. In this study we reveal trap efficiencies and how movement type can alter capture rates. Such information contributes towards improved trap count interpretations, as required in ecological studies which make use of trapping systems.

Funding

DA gratefully acknowledges the support given by Gulf University of Science and Technology (GUST), which was essential for the completion of this work. The publication has been prepared with the support of the “RUDN University Program 5-100” (to SP)

History

Citation

Methods in Ecology and Evolution, 2019

Author affiliation

/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Mathematics

Version

AM (Accepted Manuscript)

Published in

Methods in Ecology and Evolution

Publisher

Wiley for British Ecological Society

eissn

2041-210X

Acceptance date

25/04/2019

Copyright date

2019

Publisher version

https://besjournals.onlinelibrary.wiley.com/doi/abs/10.1111/2041-210X.13207

Notes

The file associated with this record is under embargo until 12 months after publication, in accordance with the publisher's self-archiving policy. The full text may be available through the publisher links provided above.

Language

en