How predictive are laboratory experiments for assessing the effects of chitin synthesis inhibitors (CSI) on field colonies of terrnites? - A comparison of laboratory and field data from Australian mound-building species of termit

IRG/WP 96-10143

M Lenz, P V Gleeson, L R Miller, H M Abbey

A singular advantage of using mound building species of termite is their directly accessible nest. This allows evaluation of control methods by accurate assessment of the effects at the colony level. The mound building species Coptotermes acinaciformis (Froggatt) and Nasutitermes exitiosus (Hill) were used to test the CSI, hexaflumuron, in laboratory and field trials. Laboratory results showed that hexaflumuron was not repellent and it eliminated four gram groups of C. acinaciformis at a dose of 125 ppm and above within eight weeks. Groups of N. exitiosus were not affected by hexaflumuron: survival and wood consumption at doses of 0.25 to 1000 ppm were no different to those at zero ppm. Similar responses were obtained with the CSI triflumuron. These results would predict elimination of colonies for C. acinaciformis but not for N. exitiosus. However, field colonies of C. acinaciformis and also of N. exitiosus could be eradicated when exposed to hexaflumuron. Larvae and earlier stages of workers and nymphs died first, most likely during moulting, whereas the older foragers, which are the stages most often used in laboratory experiments, lived the longest. The latter was most pronounced in N. exitiosus. These results are the first to show the effects of a CSI on an entire colony, and demonstrated unambiguously the elimination of colonies after foragers had fed on bait matrix treated with hexaflumuron. Laboratory evaluations, using groups of older workers and soldiers, can fail to accurately predict the impact of these products at the level of most concern, the colony.


Conference: 96-05-19/24 Guadeloupe, France

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