This is an author produced pre-print version of a paper later published in The Canadian Entomologist.
Citation for the published paper: Björklund, N. (2009) A non-destructive tree trunk funnel trap for capturing Hylobius warreni (Coleoptera: Curculionidae) ascending stems of trees. The Canadian Entomologist. Volume: 141 Number: 4, pp 422-424. http://dx.doi.org/10.4039/n09-030
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N. Björklund, page 1.
Author's Pre‑print: Björklund, N. (2009) A non-destructive tree trunk funnel trap for capturing Hylobius warreni (Coleoptera: Curculionidae) ascending stems of trees. The Canadian Entomologist 141, 422-424. doi: 10.4039/n09-030 Note that the title below was later changed to the one above.
A nondestructive tree trunk funnel trap for capturing
insects ascending stems of trees
Niklas Björklund
Department of Ecology, Swedish University of Agricultural Sciences,
P.O. Box 7044, S-750 07 Uppsala, Sweden.
E-mail: [email protected], Phone: +46 18 672879
1 N. Björklund, page 2.
1 Abstract
2 An efficient, simple, and inexpensive trap that catches insects as they ascend tree boles is
3 described. The performance of the trap was tested in a capture-mark-recapture experiment on
4 the Warren root collar weevil, Hylobius warreni Wood (Coleoptera: Curculionidae). A high
5 percentage (77%) of the marked H. warreni were recaptured at least once and a high
6 percentage of the weevils were recaptured several times, with one weevil recaptured eight
7 times. These results indicate that the trap is efficient and that weevils were not conditioned to
8 avoid the trap.
9 Introduction
10 This paper describes a simple and inexpensive trap for capturing insects ascending stems of
11 trees. The efficiency of the trap was evaluated in a mark-recapture experiment on the Warren
12 root collar weevil, Hylobius warreni Wood (Coleoptera: Curculionidae), a significant pest of
13 lodgepole pine, Pinus contorta Dougl. ex Loud. var. latifolia Engelm. ex S. Watson
14 (Pinaceae)(Cerezke 1994).
15
16 H. warreni attack trees from about age six years to maturity. It is considered a pest species
17 since its larvae may girdle and kill small diameter trees. Mortality usually does not exceed 5
18 %, but much higher mortality rates have recently been reported in Western Canada (Schroff et
19 al. 2006). There is a concern that this is in part due to the current unprecedented outbreak of
20 mountain pine beetle, Dendroctonus ponderosae Hopkins, which has killed over 10 million
21 hectares of mature lodgepole pine (Walton et al. 2008). There is an imminent risk of increased
22 weevil-caused mortality since weevils from mountain pine beetle-killed stands may migrate to
23 plantations, thus threatening future crop trees. Indeed, Klingenberg (2008) confirmed that H.
2 N. Björklund, page 3.
24 warreni causes more damage in young lodgepole pine plantations when these are adjacent to
25 areas where mountain pine beetles have killed the mature trees.
26
27 Research on H. warreni has been hampered by the lack of a suitable sampling techniques.
28 Cerezke (1994) developed a trap that he successfully used for a mark-recapture study. To my
29 knowledge, this trap has not been used successfully since, probably because it is fairly
30 complicated to build. For example, Lindgren1 (pers. comm.) failed to catch H. warreni using a
31 trap based on Cerezke‟s specifications. In short, Cerezke‟s trap consists of a metal strip that is
32 nailed around the tree stem to guide weevils into an inverted nylon mesh funnel, which leads
33 to a container from which the weevils can be collected.
34
35 Several techniques used to trap other species of weevils have also been tested on H. warreni,
36 but without success, e.g., pitfall traps baited with a variety of monoterpene mixtures with
37 ethanol and turpentine components (MacKenzie et al. 1989 cited in Cerezke 1994), circle
38 traps (described in Mulder et al. (2000)) and split pine bolts (Lindgren1, pers. comm.), night
39 time limb jarring and transparent air bubble wrap (described in (Hausmann et al. 2004))(pers.
40 obs.). The objective of this study was to develop an efficient and simple trap that could be
41 used for ecological studies of the Warren root collar weevil and insects with similar
42 behaviours.
43 Materials and Methods
44 Trap description
45 The aim of the trap is to catch insects as they ascend tree boles (e.g., H. warreni). It consists
46 of a funnel that is attached at its lower end to the stem of a tree (Fig. 1).
1 B.S. Lindgren, University of Northern BC, Prince George, BC, Canada.
3 N. Björklund, page 4.
47
48 Trap construction begins by drawing the contours of the trap, according to the photograph
49 shown in Fig. 1A, on a kraft paper which has been saturated with asphalt (e.g. Vaporex 400S,
50 Building Products of Canada Corp.). A foam brush is then used to paint a band of Fluon®
51 (e.g., AD1070, AGC Chemicals Americas, Inc.). NB Teflon® should not be used since it will
52 not prevent the insects from escaping (pers. obs.). After the Fluon has dried, the trap is cut out
53 stacked in pairs with the Fluon-coated sides facing each other (Fluon on the outside of the trap
54 will prevent the insects from entering the trap).
55
56 Traps should be installed at least a few centimetres above ground, but below the lowest
57 branches, so that insects encounter the stem first, and then climb the outside of the trap (Fig.
58 1B). Removal of branches should be avoided, since that would influence the microclimate for
59 the insects. However, if branches must be removed to attach the trap, the wounds should be
60 covered with for example liquid paper so that pitch does not drip down into the trap.
61
62 Wrap tape around the stem a few centimetres above the point where the lower end of the trap
63 will be attached, and paint it with Fluon. If the Fluon-coated tape is at the same height as the
64 bottom of the trap all captured insects will be coated with Fluon. Tape with a glossy surface,
65 e.g., standard packaging tape, is preferable. The trap is folded to form a cone with the lower
66 part fitting tightly against the stem of the tree. A paper clip is attached to the top edge of the
67 trap to stabilize it. Short pieces of tape are then attached around the bottom of the trap as a
68 “skirt”. A tape with a non-glossy surface, e.g., five cm wide masking tape, should be used for
69 this. A few firm wraps of the tape around the stem are used to tightly attach the “skirt” to the
70 stem.
71
4 N. Björklund, page 5.
72 For insects that can fly the probability of them escaping is minimized by keeping the distance
73 without Fluon in the bottom of the trap to a minimum. Moistened paper may be used in the
74 bottom of the funnel to provide shelter for the insects. Long forceps are useful to remove
75 trapped insects from the trap. If the trap is going to be used for pest management purposes,
76 contact insecticide treated cloth, or granular insecticides, can be placed in bottom of the
77 funnel.
78 Field test of the trap
79 A field experiment was conducted near Prince George in northern British Columbia, Canada.
80 Traps were set up on all 182 trees in one half of a young lodgepole pine stand. Tree diameters,
81 measured at ground level, ranged from 4 – 14 cm. All H. warreni that were caught during the
82 first day were individually marked using liquid paper and released. The traps were emptied
83 daily during a twelve day long period in the end of May - beginning of June, 2006. All
84 captured weevils were released below the trap where they were caught.
85 Results and Discussion
86 The following three results indicate that the tree trunk funnel trap is efficient and that there is
87 no evidence of trap avoidance:
88
89 A high percentage (77%) of the marked H. warreni were recaptured at least once. Cerezke
90 (1994) recaptured a lower percentage (43%) of individually marked H. warreni with his trap
91 even though he used more traps and they were used during a longer time period. The
92 relationship between time since release and the percentage of weevils that were recaptured
93 was expected to be best explained by an exponential rise to max function. However, a simple
94 linear regression explained more of the variation (Fig. 2A). This result may be because there
95 was no enclosure around the experimental area. A substantial proportion of the marked
5 N. Björklund, page 6.
96 weevils may therefore have visited trees outside the area and thereby avoided being trapped
97 for a relatively long time period in comparison with the total duration of the experiment. It is
98 therefore likely that an even higher proportion of the weevils would have been recaptured if
99 the experiment had been continued.
100 There was no trend over time with regard to the total number of H. warreni caught each day
101 (Fig. 2B).
102 A high percentage of the weevils were recaptured several times (Fig. 3), with one weevil
103 recaptured eight times. This indicates that weevils were not conditioned to avoid the trap.
104 In a previous study it was shown that the tree trunk funnel trap catches both males and
105 females in approximately equal proportions (Öhrn et al. 2008). Few non-target insects are
106 captured with this trap compared to the mass of insects captured by conventional pitfall traps.
107
108 The tree trunk funnel trap is easy to construct, easy to attach to tree trunks, lightweight, easy
109 to transport, and very cheap (<$1 each). The trap has already successfully been used to collect
110 adult species of H. warreni in a study where two non-destructive techniques to determine the
111 sex of live adults were developed (Öhrn et al. 2008) and to a feeding and ovipositional
112 experiment (Hopkins et al. in press). The trap has also been used to study the dispersal of H.
113 warreni within modified forest habitats (Klingenberg et al. submitted). In addition, the trap
114 has proven to be efficient for trapping Hylobitelus xiaoi Zhang, a serious pest on slash pine,
115 Pinus elliottii Engelm. (Wen2, pers. comm.).
116
117 In the future the trap may be useful both for collecting insects for laboratory studies, field
118 experiments, and possibly for pest management. It could potentially be useful to study any
119 insect that crawl up the stems of their hosts; the following list of potential target species is far
2 X. Wen, Jiangxi Forest Pest and Disease Control Station, Nanchang, China.
6 N. Björklund, page 7.
120 from complete: Anthonomus pomorum L., Artipus floridanus Horn, Asynonychus godmani
121 Crotch, Conotrachelus nenuphar Herbst, Curculio caryae Hinds, Diaprepes abbreviatus L.,
122 Hylobius pales Herbst, Hylobius radicis Buchanan, Pachylobius picivorus Germar, Pissodes
123 strobi Peck, Sciaphilus asperatus Bonsdorff, and members of the genus Otiorhynchus.
124 Acknowledgements
125 I wish to thank B. Staffan Lindgren and Peter Dalin for language editing and suggestions.
126 References
127 Cerezke, H.F. 1994. Warren rootcollar weevil, Hylobius warreni Wood (Coleoptera: 128 Curculionidae), in Canada: ecology, behavior, damage relationships, and management. 129 The Canadian Entomologist, 126: 1383-1442.
130 Hausmann, C., Samietz, J. and Dorn, S. 2004. Significance of shelter traps for spring 131 monitoring of Anthonomus pomorum in apple orchards. Entomologia Experimentalis 132 et Applicata, 112: 29-36.
133 Hopkins, G.R., Klingenberg, M.D. and Aukema, B.H. in press. Feeding and ovipositional 134 behaviour of Hylobius warreni Wood (Coleoptera: Curculionidae) on host and non- 135 host foliage. Agricultural and Forest Entomology.
136 Klingenberg, M.D. 2008. Spatiotemporal associations between forests impacted by mountain 137 pine beetle and adjacent replantings impacted by warren root collar weevil. Master's 138 Thesis, University of Northern British Columbia.
139 Klingenberg, M.D., Björklund, N. and Aukema, B.H. submitted. Seeing the forest through the 140 trees: differential dispersal of Hylobius warreni Wood within modified forest habitats.
141 Mulder, P.J., McGraw, B.D., Reid, W. and Grantham, R.A. 2000. Monitoring adult weevil 142 populations in pecan and fruit trees in Oklahoma. Oklahoma State University 143 Extension Facts, EPP-7190: 1-7.
144 Schroff, A.Z., Lindgren, B.S. and Gillingham, M.P. 2006. Random acts of weevil: A spatial 145 analysis of Hylobius warreni attack on Pinus contorta var. latifolia in the sub-boreal 146 spruce zone of Northern British Columbia. Forest Ecology and Management, 225: 42- 147 49.
148 Walton, A., Hughes, J., Eng, M., Fall, A., Shore, T. , Riel, B. and Hall, P. 2008. Provincial- 149 level projection of the current mountain pine beetle outbreak: update of the infestation 150 projection based on the 2007 Provincial Aerial Overview of Forest Health and 151 revisions to „„the model‟‟ (BCMPB.v5). (online) Available from 152 http://www.for.gov.bc.ca/hre/bcmpb/ (accessed 18 February 2009).
7 N. Björklund, page 8.
153 Öhrn, P., Klingenberg, M., Hopkins, G. and Björklund, N. 2008. Two non-destructive 154 techniques for determining the sex of live adult Hylobius warreni. The Canadian 155 Entomologist, 140: 617-620.
156
8 N. Björklund, page 9.
157 Figure captions
158 Fig. 1. The tree trunk funnel trap-unfolded (A) and the placement and appearance of a
159 properly placed trap in the field (B). I = 30 mm (width of strip at the bottom of the trap
160 without Fluon, which will prevent the insects from becoming covered with Fluon), II = 70
161 mm (this relatively wide area with Fluon will prevent litter from providing a bridge for insects
162 to escape), III = 30 mm (width of strip at the top of the trap without Fluon, which will prevent
163 that insects encountering the Fluon in II from grabbing the edge of the trap with their back
164 legs, thus avoiding being trapped). IV = the maximum tree diameter that the trap can be
165 attached to.
166
167 Fig. 2. Rate of recapture of individually marked Hylobius warreni (A), and total number of H.
168 warreni caught each day (B).
169
170 Fig. 3. Number of recaptures for 35 individually marked Hylobius warreni during a 12-day
171 period.
172
9 N. Björklund, page 10. 173 Fig. 1.
174
175 176 A 177
I II III IV IV
B
10 N. Björklund, page 11. 178 Fig. 2.
80 A 70 y = 5.7143x + 9.2308; r2 = 0.9500; P = <0.0001
60
50
40
30
Percent recaptured 20
10
0 200 B 150 y = 0.9451x + 51.1758; r2 = 0.0263; P = 0.5962
H.warreni 100
50
# caught 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13
179 Days since release
180
11 N. Björklund, page 12. 181 Fig. 3.
10 9 8 7 6 5 4 H. warreni 3
# 2 1 0 0 1 2 3 4 5 6 7 8
182 # recaptures
183 184 185
12