DOI: 10.5061/dryad.x0k6djhfq
title: The neglected impact of tracking devices on terrestrial arthropods

description: Tracking devices have become small enough to be widely applied to
 arthropods to study their movement. However, possible side effects of
 these devices on arthropod performance and behaviour are rarely
 considered. We performed a systematic review of 173 papers about research
 in which tracking devices –Radio Frequency Identification (RFID), harmonic
 radar, and radio telemetry tags– were attached to terrestrial arthropods.
 The impact of such tags was quantified in only 12% of the papers, while in
 40% the potential impact was completely disregarded. Often-cited rules of
 thumb for determining appropriate tag weight had either no empirical basis
 or were misconstrued. Several properties of a tracking device (e.g.
 weight, balance, size, drag) can affect different aspects of an
 arthropod’s life history (e.g. energy, movement, foraging, mating). The
 impact can differ among species and environments. Taken together, these
 tag effects can influence the reliability of obtained movement data and
 conclusions drawn from them. We argue that the impact of tracking devices
 on arthropods should be quantified for each (1) study species, (2) tag
 type, and (3) environmental context. As an example, we include a
 low-effort impact study of the effect of an RFID tag on a digger wasp.
 Technological advancements enable studying the movement of arthropods in
 unprecedented detail. However, we should adopt a more critical attitude
 towards the use of tracking devices on terrestrial arthropods. The
 benefits of tracking devices should be balanced against their potential
 side effects on arthropods and on the reliability of the resulting data.
description: We systematically reviewed the published literature on the use of
 tracking devices on terrestrial arthropods. We searched ISI Web of Science
 (conducted on 26 August 2019) and scanned reference lists to include
 additional papers if accessible through the internet or via the authors.
 Only primary studies about terrestrial arthropods were selected.
 Non-arthropod terrestrial invertebrates, such as slugs and snails
 (Gastropoda), were not included as their ecology is highly different from
 that of terrestrial arthropods. Other kinds of tags or markings (e.g.
 numbered labels, coloured markings, or biotelemetry; the latter being tags
 to measure physiological and energetic variables remotely; Cooke et al.,
 2004), were also not considered. We selected 173 relevant papers,
 extracted information about the species, tracking devices, and the
 assessment of possible effects of these devices. Relevant variables
 collected for this study are species name, order and family, IUCN status,
 pest status, tag type, mode of movement, duration of tracking, mass of
 species and/or tag, the tag-to-body mass ratio, and whether the impact was
 discussed or quantified. We tested the effect of RFID
 tags on the general behaviour of the digger wasp <em>Bembix
 rostrata</em>. In the field, we used a calliper to measure
 inter-tegular distance (ITD), maximum width of forewing (FW), and maximum
 length of forewing (FL). ITD is highly correlated with dry mass in bees
 and wasps (Cane, 1987; Ohl & Thiele, 2007) so we used it as a
 proxy for mass. The area of an ellipse with FW and FL as axes was used to
 approximate wing area. Wing loading was then calculated as ITD divided by
 wing area. RFID tags measured 8 mm x 2 mm and were encapsulated in glass
 vials to withstand the digging in the sand. The entire tag weighed 55 mg
 (Eccel Technology LTB, UK). The tags were glued on the dorsal thorax
 (scutum) with cyanoacrylate glue. Using a fully crossed (BACI) design
 (Smith, 2002), we tested the impact of the tags on the behaviour of the
 individuals in cubic insect cages with a side length of 30 cm (BugDorm,
 Taiwan). For 12 minutes the behaviour of the individual was noted every 30
 seconds as flying, crawling, resting, washing, digging, or biting. After
 twelve minutes, half of the wasps were tagged and the other half was
 similarly manipulated but without attaching the tag to mimic the tagging
 procedure. After the treatment, the behaviour of the wasp was again
 recorded for 12 minutes. The test was performed on 94
 individuals. Percentages of a certain behaviour were analysed using a
 generalized linear mixed model with a binomial distribution and logit link
 function. Wasp individual was included as a random effect to account for
 repeated measurements. Fixed effects were BA (before or after; 2 levels),
 CI (control or impact; 2 levels), and WL (wing loading; continuous) or ITD
 (continuous). Our main interest is the tag effect (BA:CI-interaction) and
 how this tag effect depends on WL or ITD (3-way interaction). We used the
 function ‘mixed’ from the R-package ‘afex’ (Singmann, Bolker, &
 Westfall, 2019), which uses likelihood ratio tests.
description: For the dataset on the effect of RFID tags, following
 abbreviations were used: f flying, c crawling, r resting, w washing,
 d digging, b biting. Measurements (ITD, WL, WW) were all taken three times
 and averaged.