Rapid Testing of Resistance of Timber to Biodegradation by Marine Wood-Boring Crustaceans

Summary

This protocol presents a method for assessing the feeding rate of the wood-boring crustacean, Limnoria, by measuring faecal pellet production. This method is designed for use in non-specialist labs and has potential for incorporation into standard testing protocols, to evaluate enhanced wood durability under marine conditions.

Abstract

Wood-boring invertebrates rapidly destroy marine timbers and wooden coastal infrastructure, causing billions of dollars of damage around the globe every year. As treatments of wood with broad spectrum biocides, such as creosote and chromated copper arsenate (CCA), are now restricted in marine use by legislation, naturally durable timber species and novel preservation methods of wood are required. These methods undergo testing in order to meet regulatory standards, such as the European standard for testing wood preservatives against marine borers, EN 275. Initial investigation of durable timbers species or wood preservative treatments can be achieved quickly and inexpensively through laboratory testing, which offers many advantages over marine field trials that are typically costly, long-term endeavours. Many species of Limnoria (gribble) are marine wood-boring crustaceans. Limnoria are ideal for use in laboratory testing of biodegradation of wood by marine wood-borers, due to the practicality of rearing them in aquaria and the ease of measuring their feeding rates on wood. Herein, we outline a standardizable laboratory test for assessing wood biodegradation using gribble.

Introduction

Wood-borers can cause extensive damage to marine wooden structures, such as sea defences, piers, and aquaculture structures; the replacement or restoration of which costs billions of dollars per annum worldwide^1,2,3. In order to protect these structures, timber is often treated to reduce biodegradation. However, due to the restriction of use of broad-spectrum biocides in Australia, EU, UK, and USA, in the marine environment, new modification techniques and species of wood that are naturally durable to borers are sought after^4,

Protocol

1. Preparing Test Sticks

1. After any treatment processes are complete, cut dry wood into test sticks to size 2 mm x 4 mm x 20 mm (Figure 1). Air dry sticks to a constant weight, under laboratory conditions. Use at least 5 replicates of each wood being tested.

Figure 1: Tes.......

Discussion

Prior to selecting gribble specimens to be used in the feeding experiment, individuals should be screened to assess their suitability. There can be some variation in feeding rate between individuals due to differences in size, so only fully grown adult specimens should be selected. No significant difference between feeding rate of individuals between 1.5 mm and 3 mm length was detected by Borges et al., 2009¹⁷. Female Limnoria brood their eggs, during which time have a reduced feedin.......

Materials

Name	Company	Catalog Number	Comments
12-well cell culture plates	ThermoFisher Scientific	150200
50ml Falcon tubes	Fisher Scientific	14-432-22
Adjustable volume pipette	Fisher Scientific	FBE10000	1-10 ml
Beech	G. Sawyer (consultant in timber technology)	Fagus sylvatica	Taxonomic authority: L
Ekki	G. Sawyer (consultant in timber technology)	Lophira alata	Taxonomic authority: Banks ex C. F. Gaertn.
Forceps	Fisher Scientific	10098140
Incubator	LMS LTD	INC5009
Microporous specimen capsules	Electron Microscopy Sciences	70187-20
Petri dish	Fisher Scientific	FB0875713
Scots Pine	G. Sawyer (consultant in timber technology)	Pinus sylvestris	Taxonomic authority: L.
Size 00000 paintbrush	Hobby Craft	5674331001	Size 000 or 0000 also acceptable
Sweet Chestnut	G. Sawyer (consultant in timber technology)	Castanea sativa	Taxonomic authority: Mill
Turpentine	P. Evans (Professor, Dept. Wood Science, University of British Columbia)	Syncarpia glomulifera	Taxonomic authority: (Sm.) Nied.
Vacuum desiccator	Fisher Scientific	15544635