field tests of molybdenum and tungsten baits - IRG. International ...

More documents

Recommendations

Info

adhesive under low pressure and then the molding was cut to give bait stakes (15x 40x250mm). Table 1 Bait formulation for field tests Materials Contents Na2MoO4・2H2O (MW:242) Na2WO4・2H2O (MW:330) BaCl2・2H2O (MW:244) Rubber tree chips Phenolic-type adhesive 13.0 % (5.2% as Mo) 5.0 (2.8% as W) 15 57~61 6~10 Total 100 2.2. Test methods Ten and more termite mounds at Phuket Rubber Experiment Station were selected as test sites. On April of 2002, 4-6 test bait stakes (15x40x250mm) were hit into the ground around each mound, and stakes of rubber wood (40x40x300mm) were set on the top of each mound and around it if necessary. Then the level of termite activities at each mound were observed at intervals. In case that damages of test bait stakes and wood stakes were found to be serious on the observation time of October of 2002, the stakes were replaced for new ones and the tests were continued. 3. RESULTS AND DISCUSSION 3.1. Determination of bait formulations Ahead of this field tests, bait formulations containing sodium salts of molybdic acid and tungstic acid, not converted to barium salts, were tested. The result was unsatisfactory, as water-soluble sodium salts leached out during the tests. Then we prepared solid and hard baits by hardening with phenolic-type adhesive under high temperature and high pressure, but the baits invited a reduction in bait feeding by termites. For this field tests therefore, barium salt-based baits were prepared by converting sodium salts to slightly water-soluble barium salts by ion exchange method, being free from the danger of leaching out of active ingredients. Moreover, bait feeding by termites was found not to deteriorate as the baits can be formed porously under low pressure. As base materials for baits, rubber trees were suited for termites in Thailand, although favorable base materials in Japan and China were pine trees and eucalyptus barks or bagasse respectively. This seems to indicate diversity in bait feeding according to termites on the spot. 3
3.2. Outline of observation results after installation of baits Results of typical test sites are summarized as Table 2. Test site Table 2 Observation results Date of installation Date of observation 2002, 4 2002, 10 2003, 12 I ･ Five stakes were hit into the ground around a termite mound. II ･ Five stakes were hit into the ground around a termite mound. ･ Damage was found on one stake. ･Activities of Macrotermes were observed. ･ Damage was found on one stake. ･Severe damage was found on wood stakes. ･Activities of Macrotermes were observed. ･Eradication of a nest of Macrotermes was confirmed. ･Three satellite nests of Hypotermes were found around the former termite mound. ･Live termites were not found after digging out a nest of Macrotermes. ･Eradication of the nest was confirmed. After one and a half years from the start of the test, termite mounds having a height of about 30 cm at the beginning became flat as shown in Pictures. Thus it was confirmed that our bait formulations eventually eradicated termite colonies of Macrotermes and Odontotermes which attack rubber trees. Fig. 1 Start of the test Fig. 2 After one and a half years 4
Page 1 and 2: IRG/WP 04-30345 THE INTERNATIONAL R
Page 3: termites make mud tubes under the e

field tests of molybdenum and tungsten baits - IRG. International ...

Create successful ePaper yourself

Delete template?

Save as template?