Effect of hexaflumuron on mortality of the Western subterranean termite (Isoptera: Rhinotermitidae) during and following exposure and movement of hexaflumuron in termite groups

Abstract

The effects of hexaflumuron consumption on the mortality of workers of the Western subterranean termite, Reticulitermes hesperus Banks, were observed following various exposures to a substrate treated with 14C-labeled hexaflumuron at 5 g kg(-1). Uptake of hexaflumuron by workers was rapid, peaking at approximately 280 ng hexaflumuron per termite 12 days after exposure. The onset of mortality began at day 8, with cumulative mortality reaching approximately 96% by day 45. Excretion of hexaflumuron from worker termites was rapid following various exposure periods, half-lives ranging from 2.1 to 4.7 days. Trophallaxis among worker termites was efficient, hexaflumuron levels in recipient termites approaching two-thirds of levels present in donor termites feeding continuously on hexaflumuron-treated filter paper. The effect of donor-to-recipient group ratios was negligible on the amounts of hexaflumuron transferred from donors to recipients. In laboratory tests, hexaflumuron diffused from a feeding source within 7 days. The presence of additional food sources appeared to inhibit movement of hexaflumuron. Movement of hexaflumuron by cannibalism and coprophagy occurred, but was significant only when termites were starved. Hexaflumuron also appeared to adversely affect egg development by preventing hatch. Hexaflumuron was readily transferred through termite groups, effectively suppressing laboratory populations of R hesperus. Variable efficacy in field situations employing baiting with hexaflumuron in southern California may be a consequence of sporadic feeding at bait stations, the rapid clearance of hexaflumuron from individual termites, and the difficulties in bait presentation (low foraging activity, poor bait station foraging fidelity) inherent in the foraging characteristics of the Western subterranean termite.

Combinatorial Potential of bait matrix against subterranean termites under lab and field conditions

“…This likely reflects the fact that queen receives less food, nursing, and grooming by workers following the drastic decrease in the worker population, which in turn reduced their reproductive capacity. This finding is also reported by other termite investigators in other parts of the world (Peppuy et al, 1998;Rajos & Morales-Ramos, 2004;Haagsma & Rust, 2005). Nevertheless, we don't deny the possibility of toxicants eliminating or suppressing termites both lower and higher colonies if the test colonies are given more time to accumulate up to lethal level.…”

Colony Elimination of Subterranean Termites by Bait Application Using Benzoylphenylurea Compounds, with Special Reference to Bistrifluron

“…If they were recipients, they received some bistrifluron from donors that originally took bistrifluron at site 1. This was quite possible because only a small portion of materials taken up by donors would be transferred to recipients (Sùarez & Thorne 2000;Haagsma & Rust 2005;Buczkowski et al, 2007). If they were donors, they consumed bistrifluron at site 1 and were caught at sites 2 or 3 after losing some portion of the bistrifluron through trophallaxis and metabolism.…”

“…However, it is possible that some proportion of bistrifluron is transferred to nestmates by frequent trophallaxis within a short period of time. For example, the largest proportion of hexaflumuron taken by Reticulitermes hesperus Banks in California was transferred from donors to recipients after exposure to hexaflumuron bait for a day (Haagsma & Rust, 2005). In addition, the materials transferred from donors to recipients seem to be retransferred to other nestmates by cascade events (Sùarez & Thorne 2000).…”

Lethal dose and horizontal transfer of bistrifluron, a benzoylphenylurea, in workers of the Formosan subterranean termite (Isoptera: Rhinotermitidae)

“…For example, the largest proportion of hexaflumuron taken up by Reticulitermes hesperus Banks in California was transferred from donors to recipients after exposure to hexaflumuron bait for a day. 20) In addition, the materials transferred from donors to recipients seem to be retransferred to other nestmates by cascade events. 21) Further studies are needed to clarify these points.…”