Quantifying Corticolous Arthropods Using Sticky Traps

This protocol can be used to estimate short and long term community structure of corticolous arthropods. This technique is useful for capturing both flying and crawling arthropods and facilitates easy laboratory analysis. To begin this procedure measure the diameter of a tree at breast height.

Use a bark shaver to begin removing the bark at this height in each cardinal direction in an area the size of the pre-manufactured sticky trap. Continue shaving until the area is smooth enough to staple the sticky trap onto the tree with minimal space underneath that arthropods could crawl into. Next use a dark colored permanent market to label the back of the trap with the date, trap number, location, and any other pertinent information.

To trap both flying and crawling arthropods open and remove the sides and cover up the sticky trap by cutting the cardboard along the edge of the sticky material. To exclude flying arthropods from landing directly on the trap open the trap as directed on the box. Place one trap on each previously shaved location so that the openings are oriented vertically to maximize the capture of arthropods crawling up and down the tree boles.

For traps with the tops removed to capture both flying and crawling arthropods orient the traps so that the end where the opening was is oriented vertically to maintain trapping consistency. Then staple the traps to the tree by placing one staple at each corner and one staple in the center bottom and one in the center top of the trap starting with the bottom right corner and working clockwise. Take care to ensure that the entire bottom and top of each trap is flush against the tree to minimize arthropods crawling underneath.

Leave the traps in place for the desired amount of time making sure to leave all traps for the same amount of time. After the desired amount of time has passed cover the entire trap except for the staples with polymer cellulose film. Remove each trap by taking a large flat screwdriver and prying each staple partially from the tree.

Then use large needle-nose pliers or a similar grasping tool to pull the staples from the tree. Alternatively to exclude flying arthropods close the trap following the directions on the back of the box. Place the traps in a rigid box to transport them back to the laboratory for analysis.

If traps are to be stored for more than 12 hours place them in a freezer to preserve their contents. Using a dissection scope examine the contents of a trap recording the number of individuals to the desired taxonomic level. Use the recorded data to estimate richness, diversity indices, or abundance.

If estimated biomass is desired measure the length and width of the arthropods to the nearest millimeter and use published length and width biomass regressions to estimate biomass. Subtract the total width of the traps from the measured diameter for each tree to estimate trapping effort for each tree. As the samples from multiple traps on the same tree are not independent either sum all of the samples from the same tree or include an individual tree as a random variable in all analysis to avoid pseudo-replication.

Based on the mixed model results the model that included tree species best explained variation and total arthropod length, abundance, and diversity. Neither of the independent variables explained substantial variation in richness, although the models that included tree species trapping effort were competitive with the null model. In addition proportion of the tree trapped appears to have no influence on abundance, total length, and Shannon diversity with only minimal influence on richness.

The standard error of the main for total arthropod length varied from four percent of the mean in tulip poplar to 17%in sugar maple. Abundance had similar levels of variation within species where the standard error of the mean is seven percent in tulip poplar and 18%in sugar maple. Conversely variability in arthropod richness and diversity was much lower within species of tree.

In that the standard error of the mean of richness ranged from four percent of the mean for pignut hickory to nine percent of the mean in American beach. While diversity ranged from four percent of the mean in American beach to seven percent of the mean in tulip poplar. When shaving the bark from the tree be certain to shave the area as smooth as possible and minimize any gaps between the tree and the edge of the trap.