Use of Acetaminophen for Large-Scale Control of Brown Treesnakes

Abstract

Because the brown treesnake (Boiga irregularis) has virtually extirpated the avifauna on Guam and is a threat to other Pacific islands, the development of alternative and efficient control methods is required. Therefore, we performed a large-scale field experiment to determine whether the acetaminophen baits we developed could be used to reduce population levels of brown treesnakes on Guam. Toxic baits were made by inserting 80 mg of acetaminophen into dead neonatal mice, and these mouse baits were used to treat plots. Reference plots were baited with unadulterated baits. We used mark-recapture methods to estimate snake abundance on plots before treatment, monitored bait-take rates on treated plots for 30 days, and used mark-recapture to estimate snake populations post-treatment. Bait-take rates were reduced on treated plots by 83% relative to reference plots after 14 days, when they reached an asymptote. Using a robust design model in program MARK, snakes on reference plots had higher apparent survival rates (? = 0.3505) than those on treated plots (? = 0.0072) for the duration of the study, but estimates were influenced by snake movement between plots. When we accounted for movement using a multistrata model, survival on treated plots was estimated as zero. High mobility of brown treesnakes presents difficulty for complete removal of snakes from large areas, but we conclude that acetaminophen baits may provide an effective and selective management tool for quickly and efficiently reducing populations of brown treesnakes on Guam.

Objectives and integrated approaches for the control of brown tree snakes: An updated overview

“…The other is aerial bait distribution using biodegradable devices to hang baits in canopy vegetation where they would most likely be encountered by BTS. Similar to trapping, bait stations on plot perimeters with similar spacing as traps have been found to be an efficient and effective strategy for suppressing the snake population inside the plots (Savarie et al, 2001c;. Aerial baiting holds promise as an economical and selective method for reducing BTS populations over large landscapes with little non-target risk .…”

“…Commercially available DNM are very effective for delivering acetaminophen to BTS in the field (Savarie et al, 2001c). DNM baits are so well accepted by BTS that bait take is a reliable method for monitoring BTS abundance .…”

“…Rotenone, propoxur, natural pyrethrins, allethrin, resmethrin, diphacinone, warfarin and aspirin were found to be orally toxic to BTS (Brooks et al, 1998b). Of three subsequently tested non-narcotic analgesic drugs delivered in dead neonate mice (DNM) as a matrix (Savarie et al, 2000(Savarie et al, , 2001c, only acetaminophen was highly effective (aspirin was moderately effective, and ibuprofen was ineffective). Snakes ingesting an 80 mg dose died in less than 48 h (Savarie et al, 2001c).…”

Tools for managing invasions: acceptance of non-toxic baits by juvenile Nile monitor lizards and Burmese pythons under laboratory conditions

“…Similarly, toxicants could possibly play a role in controlling Nile monitor lizards and Burmese pythons. Dead neonatal mouse (DNM) baits treated with acetaminophen are effective for reducing brown tree snake populations under field conditions on Guam (Savarie et al 2001). More recently, acetaminophentreated DNMs were found to be lethal to juvenile Nile monitor lizards and Burmese pythons under laboratory conditions (Mauldin and Savarie 2010).…”

“…Campbell 2005;Mauldin and Savarie 2010). Building on the successful development of acetaminophen as a toxicant for brown tree snakes (Savarie et al 2001), laboratory trials showed acetaminophen to also be effective for juvenile Nile monitors and Burmese pythons (Mauldin and Savarie 2010).…”