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2009 SOUTHEASTERN NATURALIST 8(4):733–738
Comparing Chemiluminescent and LED Light for
Trapping Water Mites and Aquatic Insects
Andrea J. Radwell1,* and Nicholas B. Camp2
Abstract - This research compared the effectiveness of red, yellow, green, and blue
chemiluminescent candles and white light from an LED source in capturing water
mites and aquatic insects in a macrophyte bed of a small reservoir. We sought to
compare the abundance of organisms captured and to determine whether specific
taxa showed a preference for certain colors. A total of 2974 organisms in 19 taxa
were collected including 7 water mite genera and 12 other invertebrate taxa. The
abundance of Hydrachnida (water mites) in the traps was greater than all other taxa
combined. The dominant insect taxa collected were Ephemeroptera and Odonata.
No statistically significant inter-taxon preferences for color were found, but overall
there was a greater attraction to yellow, green, or white light than to red and blue
light. Since white light from the reusable LED source performed as well as yellow or
green disposable chemiluminescent candles that are typically used in aquatic traps,
submersible LED fl ashlights could be considered a suitable alternative.
Abundant and diverse assemblages of lentic invertebrate species can be
found in pools, backwaters, and margins of rivers and streams and in the
littoral zone of small lakes and reservoirs. A 1-m2 area of substrate from
littoral macrophyte beds in eutrophic lakes may contain as many as 2000
juvenile and adult water mites (Acari: Hydrachnida; Smith et al. 2001). Water
mites and insects have a complex ecological relationship that includes
parasitism and predation, and together they form one of the most abundant
invertebrate groups in lentic habitats.
While nets have been effectively used to collect lentic invertebrates, they
present certain disadvantages, particularly when macrophyte beds are the
habitat of interest. Wading through the sampling area may result in dispersal
of organisms and damage to vegetation. Because collection of water mites
and early instars of insects requires nets with fine mesh, clogging is often a
problem. Samples collected using nets often include substantial amounts of
plant material and detritus that make sorting difficult. Light trapping is an
alternative that eliminates some limitations of collecting with nets in lentic
habitats and can be useful in areas that are not easily accessible.
Most studies of the preference of various insect taxa for particular
colors in light traps have been done in terrestrial environments. Barker et
al. (1997) demonstrated that yellow and white consistently attracted more
1Department of Biological Sciences, University of Arkansas, Fayetteville, AR 72701.
234 Sunrise Place, Cabot, AR 72023. *Corresponding author - email@example.com.
734 Southeastern Naturalist Vol. 8, No. 4
organisms than darker colors, such as blue, and hypothesized that herbivorous
insects are more attracted to yellow because it is the peak reflectance
of plants. Yellow was also found to be more attractive to pollen beetles
(Nitidulidae; Blight and Smart 1999), and lime green, spring green, and
yellow were shown to be most effective in collecting the majority of Bemisia
argentifolii Bellows and Perring (Silverleaf Whitefly; Aleyrodidae) and
leafhopper species (Cicadellidae) (Chu 2000). White was more attractive
to Palpita unionalis (Hübn) (Jasmine Moth; Pyralidae) when compared to
yellow (Athanassiou et al. 2004).
Research on the effect of color in light-trapping in aquatic habitats is
limited. Hungerford et al. (1955) were among the first to report on the effectiveness
of submerged light traps, and they established the usefulness
of this method for the capture of various freshwater invertebrate taxa.
In a comparison of lit and unlit traps, Pieczynski (1962) demonstrated a
strong affinity of water mites to light and suggested the usefulness of traps
for studying species that are rare but have a strong response to light. Barr
(1979) compared dipnets and traps baited with yellow-green luminescent
light for trapping water mites and found that light traps often collected
more individuals than dipnets, although the choice of yellow-green rather
than red or blue was not explained.
The utility of submersible light emitting diode (LED) fl ashlights in
aquatic light traps has not been reported. The goal of our research was to
compare the effectiveness of red, yellow, green, and blue chemiluminescent
candles and a LED fl ashlight (white light) in capturing water mites and
aquatic insects in a macrophyte bed of a small reservoir. We sought to compare
the abundance of organisms captured and to determine whether specific
taxa showed a preference for certain colors.
The experiment was conducted in Lake Leatherwood, Eureka Springs,
Carroll County, AR. Lake Leatherwood is a 34-ha impoundment of Leatherwood
Creek completed in 1944 by the Civilian Conservation Corps. A 28-m2
macrophyte bed with a depth of 50 to 82 cm was selected for submersion of
light traps. The predominant macrophytes were Potamogeton nodosus Poir.
(Pondweed; Potamogetonaceae) and Ceratophyllum demersum L. (Coontail;
Bioquip™ light traps (model #2821) were positioned at dusk and retrieved
at dawn each day for 9 consecutive days (27 Aug–5 Sept 2007). Two Ameriglo
™ chemiluminescent candles of red, yellow, green, or blue were placed
in four traps with one color per trap, and a fifth trap contained a submersible
Underwater Kinetics™ light emitting diode (LED) fl ashlight (model 09102)
powered by two AAA batteries. The traps were placed at least 1 m apart, and
2009 A.J. Radwell and N.B. Camp 735
the position of the colors relative to each other was randomly assigned each
day. Water and air temperature were measured each day at dawn.
To retrieve each sample, the trap was lifted from the bottom of the lake
and placed, while remaining submerged, into a large 250-μm mesh net to
prevent fl ushing of organisms back into the lake. The funnels on each side of
the trap were removed to wash out organisms while it was in the submerged
net. The trap was then removed from the net, and the net was pulled from the
water. The contents of the net were placed in a 1-L container of lake water.
In the laboratory, each sample was placed in a large white tray and live
organisms were collected using a pipette. Water mites were placed in modified Koenike’s solution (50% glycerine, 10% glacial acetic acid, and 40%
water), and insects were placed in 70% ethanol. Water mites were identified
to genus, and insects were identified to family.
One-way ANOVA was used to determine whether there were signifi-
cant differences in attraction to red, yellow, green, blue, or white light. The
response of all organisms combined and that of major taxa including Hydrachnida,
Insecta, Ephemeroptera, Odonata, and the water mite genus Arrenurus
were analyzed. When ANOVA results were significant (α = 0.05), least signifi-
cant difference tests were used to determine specific differences.
No spates or other notable weather events occurred during the sampling
period. Air temperature was 24 ± 2 ºC and water temperature was 28 ± 1 ºC.
The chemiluminescent candles continued to emit light until the traps were
retrieved, although the blue candles were nearly extinguished by sunrise.
The LED light provided consistent light each night.
A total of 2974 organisms were collected representing 7 water mite genera
and 12 other invertebrate taxa (Table 1). Water mites were more abundant
than insects in the traps, and the water mite genus Arrenurus was the most
abundant taxon, accounting for more than half of the total organisms. Baetid
mayfl ies were the most common insects. Very high densities of ostracodes,
cladocerans, and copepods were present in both the water column and the
traps. Since it was not possible to differentiate between those collected from
the water column while retrieving the traps and those that had been attracted
to the traps, no effort was made to analyze the response of these organisms.
In contrast, insects and mites were not apparent in the water column. While
some may have been captured in the retrieval process, the assumption was
made that their numbers were not large enough to infl uence the outcome of
Of the 19 taxa, more organisms were attracted to yellow, green, and white
light than red or blue light (P < 0.0001, Fig. 1). Water mites were more attracted
to yellow, green, and white than red or blue (P = < 0.0001). When
data for the predominant water mite Arrenurus were analyzed separately,
yellow, green, and white light captured more than red, but only green and
white captured more than red or blue (P = 0.0009). Yellow, green, and white
736 Southeastern Naturalist Vol. 8, No. 4
attracted more insects than blue, but only green attracted more than red (P =
0.0058). Ephemeroptera and Odonata, when analyzed separately, did not
produce significant results (P = 0.0563 and 0.1816, respectively).
Light-trapping provided a convenient and effective method for obtaining
information on the diversity of aquatic organisms in the lentic community
of a small reservoir. The study addressed only the response of invertebrate
taxa that are attracted to various colors or white light rather than the affinity
of various taxa for traps or light in general; thus, the observed community
composition may not refl ect the actual composition of the aquatic community.
The method was particularly effective for capturing water mites, an
invertebrate group that has received relatively less attention than insects in
studies of freshwater communities. The response of both water mites and
aquatic insects to color was consistent with earlier research on insects in terrestrial
ecosystems that found yellow, green, and white to be more attractive
than red or blue.
Table 1. Total number of organisms by taxon collected from Lake Leatherwood, Carroll County,
AR, 27 Aug–5 Sept 2007 in aquatic light traps baited with chemiluminescent candles and LED
Order/Family Genus Red Yellow Green Blue White Total
Lebertiidae Lebertia 13 25 46 24 24 132
Limnesiidae Limnesia 10 21 47 11 34 123
Hygrobatidae Atractides 2 3 0 3 2 10
Unionicolidae Neumania 16 82 70 11 34 213
Aturidae Albia 0 1 7 6 6 20
Mideopsidae Mideopsis 15 39 45 23 35 157
Arrenuridae Arrenurus 152 344 421 239 402 1558
Dytiscidae 3 8 18 5 10 44
Chironomidae 2 4 1 2 7 16
Baetidae 22 104 121 23 75 345
Caenidae 17 26 30 13 23 109
Ephemerellidae 5 7 2 1 18 33
Nemouridae 3 2 3 1 2 11
Coenagrionidae 18 4 20 4 16 62
Lestidae 2 1 1 0 4 8
Libellulidae 3 5 6 4 5 23
Gomphidae 10 11 14 7 9 51
Corixidae 1 0 0 2 0 3
Other (Amphipoda) 14 4 17 6 15 56
Total 308 691 869 385 721 2974
2009 A.J. Radwell and N.B. Camp 737
The LED fl ashlight proved as effective as the yellow or green chemiluminescent
candles; thus, it could be considered a suitable substitute for
disposable candles. The AAA batteries required replacement each day, but
Figure 1. Attraction of taxa to aquatic light trap color (ANOVA). Error bars represent
95% confidence intervals. Specific differences were determined using least signifi-
cant difference tests when ANOVA was significant (α = 0.05). Results that share the
same letter were not found to be significantly different.
738 Southeastern Naturalist Vol. 8, No. 4
rechargeable batteries offer a cost-effective alternative. The fl ashlight used
for this experiment was of relatively low intensity, yet it performed well
compared to the chemiluminescent candles. Further research is needed to
determine whether a LED light source of higher intensity or other sources of
light (e.g., halogen or UV light) would be even more effective in attracting
invertebrates in aquatic habitats.
We wish to acknowledge contributions to this research from the University of
Arkansas, Fayetteville, including the Honors College, for financial and academic
support; Jeff Velie, from the Agricultural Statistics Laboratory, for assistance
with statistical analyses; and Scott Longing, from Soil, Water and Environmental
Science, for his expertise in the taxonomy of insects. Eureka Springs Parks and
Recreation provided access to Lake Leatherwood and cooperated in the effort to
assure that the study site was not disturbed during the collection period. The willingness
of Arthur V. Brown and Janice Hinsey to provide suggestions for improving
the manuscript is appreciated.
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