Fluorescent Pan Traps Affect the Capture Rate of Insect Orders in Different Ways.

Mani Shrestha,Anders Nielsen,Jair Garcia,Thomas Tscheulin,Scarlett Howard,Justin Chua,Alan Dorin,Adrian Dyer

doi:10.3390/insects10020040

Mani Shrestha, Anders Nielsen + Show 6 more

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https://doi.org/10.3390/insects10020040

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Abstract

To monitor and quantify the changes in pollinator communities over time, it is important to have robust survey techniques of insect populations. Pan traps allow for the assessment of the relative insect abundance in an environment and have been promoted by the Food and Agricultural Organization (FAO) as an efficient data collection methodology. It has been proposed that fluorescent pan traps are particularly useful, as it has been suggested that they capture high numbers of insects in an unbiased fashion. We use a simultaneous presentation of fluorescent and non-fluorescent pan trap colours to assess how flower-visiting insects of different orders respond to visual stimuli and reveal a significant interaction between trap fluorescence and captured insect type. In particular, Coleoptera (beetles) and Lepidoptera (butterflies and moths) were captured significantly more frequently by fluorescent traps, whilst Dipterans (flies) were captured significantly less frequently by this type of pan trap. Hymenopterans (bees and wasps) showed no significant difference in their preference for fluorescent or non-fluorescent traps. Our results reveal that the use of fluorescent pan traps may differently bias insect capture rates when compared to the typical experience of colour flower-visiting insects in natural environments. Correction factors may, therefore, be required for interpreting insect pan trap data collected with different methodologies.

Highlights

Several studies have reported that global declines in insect pollinator populations are linked to phenomena including habitat fragmentation, pathogens, invasive species, climate change, and/or the widespread use of agricultural insecticides [1,2,3,4,5,6,7,8,9]
When we considered the main research question, we found a significant interaction between the type of trap, either fluorescent or non-fluorescent, and the order of insect captured (χ2 = 27.374, d.f. = 5, p < 0.001) (Figure 3)
The main analysis was followed by a residual analysis to identify those insect orders presenting significantly more or less captures than what is expected by chance (Table 2)

Summary

Introduction

Several studies have reported that global declines in insect pollinator populations are linked to phenomena including habitat fragmentation, pathogens, invasive species, climate change, and/or the widespread use of agricultural insecticides [1,2,3,4,5,6,7,8,9]. To attempt to control for potential colour preference biases, previous studies have used differently coloured pan traps such as white, yellow, and blue, as perceived by human colour vision, to quantify the broad insect diversity potentially encountered in ecological settings [14,16,21,23]. These studies have typically used UV-fluorescent pan traps based on anecdotal evidence [39,40] that such stimuli collect more insects, this factor of UV-fluorescence on insect capture rate has, only recently, been subject to formal testing [41]

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