Efficacy and Palatability of Zinc Phosphide, Pyrinuron
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MARDI Res.Bull., (1985)j'3, 3: (271-277) EFFICACY AND PALATABILITY OF ZINC PHOSPHIDE,PYRINURON AND KAYANEX AGAINST RATTAS ARGENTIVENTER Y.M. LAM* Keywords: Acute rodenticide, Zinc phosphide, Pyrinuron, Kayanex, Rattus argentiventer, Feeding tests. RINGKASAN 'tiada Racun-racun tikus seperti zink fosfida, pyrinuron dan kayanex telah diuji dalam keadaan 'pilihan' 'tiada pilihan' dan di makmal terhadap Rattus argentivenler. Keputusan ujian pilihan' menunjukkan 3.0% zink fosfida, 0.2Vo pyrinwon dan 1.07c kayanex menyebabkan kematian 7O0Voke atas kedua-dua jantina tikus ujian. Daripada ujian-ujian'tiada pilihan'dan'pilihan'tersebut menunjukkan tikus-tikus dapat mengesan zink fosfida, pyrinuron dan kayanex di dalam umpan. 'pilihan' Kepekatan yang optimum untuk zink fosfida. pyrinuron dan kayanex yang didapati dalam ujian ialah 1.5 peratus. Pengumpanan awal adalah penting untuk menjayakan kawalan bila zink fosfida. pyrinuron dan kayanex digunakan untuk kawalan R. argentiventer di sawah. INTRODUCTION the controf of R. argentiventer(Ll.t"t,1977). This paper reports studies on the efficacy The introduction of anticoagulant and palatability of zinc phosphide, rodenticides in the early 1950s,with their pyrinuron and kayanex against R. much greater safety to non-target animals, argentiventer in the laboratory. resulted in a general decline in the use of acute rodenticides. However, the appear- MATERIALS AND METHODS ance of rodents resistant to the anti- coagulantsin Europe and the United States Technical grade zinc phosphide has clearly shown that single-dose (88.3% a.i.), pyrinuron (99.97c a.i.) and rodenticides have still a role in modern kayanex (98.7o/oa.i.) were used in the trials. rodent control and this has revived interest All doses are expressed as mg/kg which in the use of acute rodenticides (Gnarz, refers to milligrammes of rodenticide per 1973). One of the most commonly used kilogramme of body weight. The laboratory acute rodenticides in the world is zinc bred R. argentiventerused in the trials were phosphide (Mvt-t-vtvtart, 1975). It was first from an out-bred colony of rats caught from used in 1911to control field rodents in Italy the rice fields of SeberangPerai, Penang. and later in other European countries (Currrv and SourHERN, 1954; Scuoop, Rats were caged singly in cages 1970).Although zinc phosphide is the most measuring 28 x 36 x 16 cm and shielded frequently used rodenticide among rice from the view of one another. Before the farmers in Malaysia (Lnlt and AeouLI-nH, tests,all rats were maintainedon laboratory 1975), detailed laboratory trials have not pelfets and water sd libitum and were been conducted to evaluate its efficacy and conditioned for two weeks before the tests palatability againstthe rice field rat, Rattus were conducted.Rats were weighedone day argentiventer (Robinson & Kloss). Lena before the start of the tests. The toxicants (1979a) reported toxicological studies of were presented in a bait-baseas described zinc phosphide, pyrinuron (pyriminyl) and by Lnu (1979b). kayanex and found them to possessgood rodenticidal properties against R. Two types of feeding experiment were ar4entiventer.Field studies indicated that carried out. no-choice and choice tests. In zinc phosphidecould be effectively used for the no-choicetests, non-poisoned baits were *Rice ResearchDivision. MARDI. Bumbonq Lima. ScbcrangPerai. Penang, Malaysia. 271 given for three days. On the fourth day it poisoned bait consumed compared with the was replaced by the poisoned bait, i.e. the mean prebait at these levels. The mean rats were given poisoned baits for one day at amount of poisonedbaits consumedwas less the various concentrationstested. In choice than 2.0 glday at 0.5Vo and at l.}Vc the tests,food pots containingthe non-poisoned amounts consumed were below 1.0 g/day and poisoned baits were placed (Table 2). The lowest lethal dose for the symmetrically in the cages. After a 24-hour males was 8.11 mg/kg and the highest dose exposure,the positionsof the two baitswere survived was 20.96 mg/kilogramme. For the inter-changed with fresh baits and clean females,the lowest lethal dosewas 8.93 mg/ pots. The above process was repeated until kg and the highest dose survived was 24.64 the tests were completed. The contents of mg/kg (Table 2). A majority of the rats died the food pots were weighed daily and the within 24 hours after ingestion of the bait consumption was recorded. At the end poisoned baits. However, in the lower con- of the tests, rats were fed laboratory pellets centrations,0.l%oand0.2Vo, about 50% of and water ad libitum and were then the rats died between two and five days. observed for 14 days. Days to death of the Mean days to death (data from the various treated rats were recorded. concentrations,tested) was 1.6 days, with a range of one to five days. RESULTS Kayanex at 0.lVo caused 50% No-choice Feeding Tests mortality in males and 407o mortality in females (Table 3). At0.5Vo kayanex caused Zinc phosphide at 0.5Vo causedmore 807o mortality in males and 9OVomortality than 50Va mortality in both sexes and at in females but at 1% kayanex, 700Vo 7.5Vo to 5.OVo the mortality of the rats mortality was induced in both sexes (Table tested was ; )7a-l00Vo (Table 1). At con- 3). The mean amounts of kayanex bait centrations greater than L5Vo, rats were consumedwere significantlylow in all tests, found to have survived the testsbecause of lessthan 1.0 g/day, comparedwith the mean bait refusal. The lowest lethal dose for prebaits of 4.31-8.66 glday. The lowest males was 3.59 mgikg and the highest dose lethal dosefor the maleswas 0.13 mg/kg and survived was 24.71mglkilogramme. For the the highest dose survived was 1I.43 mgl females,the lowest lethal dose was 3.37 mgi kilogramme. For the females, the lowest kg and the highest survived dose was 57.29 lethal dose was 1.51 mg/kg and the highest mg/kg (Table 1). Although mean poison bait dose survived was 11.72 mglkg (Table 3). consumption was low (less than 0.5 g/day) All susceptible rats died within 24 hours comparedwith the mean prebait (which was after ingestionof poisoned baits. greater than 4.73 g) rat mortality was high at the 37o and 5Volevels. in which 80Vo-l00Vo Choice Feeding Tests mortalitieswere achieved.A majority of the rats died within 24 hours after ingestion of Due to the acute action of zinc the poisoned baits. Mean days to death phosphide,pyrinuron and kayanex,only the (data from the various concentrations bait consumptions(plain and poisoned) on tested) was 1.1 days, with a range of one to the first day were used in the statistical six days. analyses. Zinc phosphide at 2Vc was un- palatable to R. argentiventer and as a result '70% Pyrinuron at 0"|Vo caused the mortality was low, 20Vo for males and mortality in males and 90Vo mortality in 50Vo for females (Table 4). At concentra- females (Table 2). N concentrations of tions of 1.5Vo and below rats did not show 0.27o, 0.57o and 1.07o pyrinuron caused significant preference for the plain baits 1007o mortality in both sexes. There was (except for males, P<0.05, at 7Vo zinc sienificant reduction in the amount of phosphide)although smaller amounts of the 272 -lo clololN \C N -l tlttttttl nomNhN ot6 tttltttl El& ol -l al E >l N 6la >l 9n\n\-:qq ol> NNF ool ^l tl ool oc:o\ ,ll bol q\cl -Sr A NNN ttttt tttl N ol rtlttl AI \\n .*l \ $ ;l ol 9l po ol F\o, N >l lO OI ttl b. 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G € ot- F-NNn600 ii-j,j-j-^i^j ddri ri .9 F v^ _a* U 1id a: .d eq9\qcq9lq9.n O'ca6-€nOcO €€oro\crn€\ocoF- Fr'o-j6i 6i d+ --N-N- $\o\o\o$r€$ o0 oo NFNFaI-F- € >; >E>Ir>!!>r!>tL>t! € a a >t!>lr>t&>i! 273 -lc) poisonedbaits were consumed(Table 4). otG tttlttl Zinc phosphideat l.5Vo was able to cause nld 80Vomortality in both sexesunder choice >l c conditions. ol>6lq bol Pyrinuron at 0.2Vocaused mortalities of 20Voin the malesand 407o in the females bol c9\-:\nO\nnNO -l ;o r,$n-- under choiceconditions (Table 5). At0.3Vo I TT I I pyrinuron caused 807o mortality in the vl.leqq -+NFO males and 40Vo mortality in the females. Femalesshowed significantpreference for ol plain baits at 0.3Vobut at 0.5% no signi- wt= noonNr ficant preference for plain baits was 9lu \nqv?nn I l NN-NTN more plain On il> detectedin both sexesalthough al baits (approximately2.5 times the mean a poisonedbaits) were consumed(Table 5).