Diphacinone with cholecalciferol for controlling possums and ship rats

Figures & data

Table 1. Average amounts of diphacinone and cholecalciferol consumed, times of behaviour changes, death and efficacy of bait for possums and ship rats.

Feature	Possums	Rats
Amount of diphacinone consumed (mg ai/kg body weight)	1.29 (range 0.46–2.47)	4.51 (range 2.64–8.33)
Amount of cholecalciferol consumed (mg ai/kg body weight)	15.50 (range 5.53–29.61)	54.10 (range 31.64–100.00)
Time of reduced feed intake (days after initial ingestion)	4 (2 days prior to death)	2 (3 days prior to death)
Time of reduced activity/symptoms (days after initial ingestion)	4 (2 days prior to death)	4 (24 h prior to death)
Change in weight over course of trial (% weight change from start to death/finish)	5.96 (range +8.29 to −9.86)	11.54 (range −3.25 to −18.85)
Number of animals killed	13/15	12/14
Time until death (days after initial ingestion)	5.77 (range 5–7)	5.08 (range 3–9)

Table 2. Pre- and post-monitoring of ship rat and possum abundance and % reduction with and without adjustments to the percentage kill estimates – based on change at the control sites.

Site	Species	Pre monitor	Post-monitoring	% reduction not adjusted	% reduction adjusted
1	Possums	6.66%	0.66%	90%	95%
1	Ship rats	26.00%	2.00%	92%	88%
1	Mice	44.00%	6.00%	86%	80%
2	Possums	10.00%	1.33%	87%	93%
2	Ship rats	12.00%	0.00%	100%	100%
2	Mice	42.00%	6.00%	86%	79%
Control	Possums	2.03%	4.00%	n/a	n/a
Control	Ship rats	16.00%	12.00%	n/a	n/a
Control	Mice	30.00%	20.00%	n/a	n/a

Table 3. Comparative average times to death for possums and rats.

	Average time to death (days)		Reference
	Possums	Rats
Brodifacoum	20.1	7.2	Littin et al. (2000)
Coumatetralyl+ Cholecalciferol	11.1	–	Sam and Ross (2012)
Cholecalciferol	–	6.4	Shapiro et al. (2011)
Cholecalciferol	7.0		Hix (2009)
Diphacinone	–	6.7	Hix et al. (2010)
Diphacinone+ Cholecalciferol	5.75	5.08	This publication

Table 4. Classification of vertebrate pesticides based on comparative pharmacokinetics and expectation of persistence of residues in sub-lethally exposed species (adapted from Eason et al. 2010b).

Group	Compound	Half-life values	Likely persistence of residues in edible tissues
1	Cyanide	+	12–24 h
	Zinc phosphide	+	12–24 h
	Para-aminopropiophenone	+	4 days
	1080	<11 h	7 days
2	Pindone	2.1 days	4 weeks
	Diphacinone	3 days in rats	6 weeks
3	Cholecalciferol	10–68 days	3 months but note: it is always present at normal physiological concentrations
	Coumatetralyl	50–70 days	4 months
4	Brodifacoum	130 days	24 months or longer
	Bromodiolone	170 days	24 months or longer
	Flocoumafen	220 days	24 months or longer

Note: + no published value but likely to be <12 h.

Littin KE, O'Connor CE, Eason CT. 2000. Comparative effects of brodifacoum on rats and possums. New Zealand Plant Protection. 53:310–315.

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Sam S, Ross J. 2012. The efficacy of C + C (cholecalciferol 0.015% and coumatetralyl 0.03%) within a paste and pellet bait on caged possums, Norway rats and mice. Unpublished Lincoln University CWMC Report. p. 6.

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Shapiro L, Hix S, MacMorran D, Eason C. 2011. The effectiveness of a low dose cholecalciferol paste bait at killing Norway rats (Rattus norvegicus) in a cage trial. Connovation Ltd unpublished internal report.

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Hix H. 2009. The effectiveness of a low dose cholecalciferol bait at killing rats and mice. Connovation Limited, Auckland, New Zealand. Internal report. p. 8.

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Hix S, Murphy E, Ross J, Shapiro L, Macmorran D, Eason C. 2010. The effectiveness of a single-feed of a bait containing a combination of diphacinone and cholecalciferol bait at killing rats Connovation Ltd Report.

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Eason CT, Ross J, Clapperton K. 2010b. Review of VTA buffer zone specifications for animal procurement, report for ministry of primary industries. Wellington, NZ: New Zealand Food Safety Authority. p. 72.

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