Med. Entomol. Zool. 56(3)

CMed. CMed. Entomo l. 200 1. Vo l. 56 NO.3 p.191 ー 199 2005J E 町ects of ivermectin on target and non-target dung-breeding flies (Diptera) in cattle dung pats Mitsuhiro IWASA 1) ，Masumi MARUYAMA 1) ，4) ， Eri NAKAMURA 1)， Nobuo YAMASHITA 2) and Akira WATANABE 3) 1 1Laboratory of Entomology ， Obihiro University of Agriculture and Veterinary Medicine ， lnada-cho ，Obihiro ，Hokkaido ，080-8555 japa η 2 1Livestock Environment Laboratory ， National Agricultural Research Center for Tohoku Region ， Natio η al A gricultural Research Organization ，4 Akahira ，Shimo-kuriyagawa ， Morioka ，lωα te ，020 -0198 japan 31 31 Meat Quality Control Labor α，tory ， National Agricultural Research Center for Tohoku Region ， National National Agricultural Research Org αnizatio η，4 Akahira ，Shimo-kuriyagawa ， Morioka ，lwate ，020 -0198 japan 41 41 Cu 作 'ent address: lndependent Administrative lnstitution National Livestock Breeding Breeding Ce η ter Nagano Station ，Arakoda 1889 ， Saku-city ，Nagano ，385 -0007 japan Received: (Received: 12 October 2004; Acc epted: 25 April 2005 ) Abstract: Abstract: The effects of antiparasitic drug ，ivermectin ，on the dung-breeding flies flies were studied in laboratory and field experiments in Hokkaido ， Japan. In two pour-on pour-on treatments (500μg jkg) ， ivermectin was excreted in dung for up to 14 and 21 days after treatment ， with peaks at 3 days and 1 day ，respectively. Dung from treated cattle cattle prevented the larval developm 巴nt of Haematobia irritans and Neomyia cornicina up to 14 days and reduced the larval and pupal survival rates at 21 days after treatmen t. In the field experiment using emergence traps ， the numbers of emerged flies flies from dung pats were 3，655 (18 families) in control dung and 2，234 (16 families) in treated treated dung. Especially ，Musca bezzii ，Ravinia stri αta ，Se ρ sis du ρlic αtα ，Se ρ sis thora- cica ， Setsis cynitse α，Sphaeroceridea ，Empididae ， Sciaridae and Chironomidae were severely severely reduced in treated dung. Reduction of cyclorrhaphaous flies similarly occur- red red at 1，3 and 7 days after treatment ，which coincides with high concentrations of ivermectin. ivermectin. Conversely ， Ceratopogonidae and Phoridae increased in treated dung ， regardless regardless of days (1 ，3 and 7) after treatm 巴nt. Dry weights of flies emerged from dung pats pats of treated cattle in the field experiment were only 5.8 % of those from dung of control control cattle ，indicating that dung-decomposing activity by fly larvae was supressed in in dung of treated cattle Key words: ivermectin ，pour-on ，Haem α tobia irritans ，Neomyia cornicin α， non-target species ， dung-breeding flies ous formulations. Whatever the formula- INTRODUCTION tions ，ivermectin is excreted in cattle feces or dung pats (Campbell et al.， 1983) ，where Ivermectin is a broad-spectrum parasiti- it retains insecticidal activity: this has a cide cide against nematode and arthropod par- novel role of control of pest flies inhabit- asites asites of domestic livestock. This drug is ing dung. However ，ivermectin residues used in many parts of the world since its in dung have a potential impact on non- introduction in the early 1980s ，because it target organisms and cause undesirable is is effective and convenient to use by vari - environmental consequences by interfer- 192 Med. En tomo l. 2001 ing ing with dung-breeding insects involved Determin α tion 01 ivermevtin concentrations in in the degradation of dung on pasture Determination of ivermectin concentra- (Wall (Wall and Strong ，1987) . tion in feces was performed by high- It It is well known that pest flies are only a performance liquid chromatography few in dipterous fly fauna of cattle dung (HPLC) following the method of Payne et pats pats in pasture; a large majority is non- al. ( 1995) with some modifications : the ex- pest pest (Hammer ， 1941; Laurence ， 1954; traction was carried out by homog en izer Papp ， 1970). The effects of ivermectin on (PHYSCOT RON ， Microtec Co. ， Lt d. ) at these these non-target dipterous flies in dung 10 ，000 rpm for 1 min instead of son ica- pats pats have been inv estigated by Ward- tion ，and avermectin B1 was added as in- haugh and Rodriguez-Menendez (1 988) ， ternal standard. Madsen et al. (1 990) ，Sommer et al. (1 992) ， Strong and Wall (1 994) ， Floate (1 998) ， Lα boratory bioass αys : Effects 01 ivermectin Floate Floate et al. (2001). on ρuρα tion and emerge nce 01 Haem ato bia 1n 1n Japan ， ivermectin has been used on irritans (Linnaeus) αnd Neom yia cornicina cattle cattle throughout the country ，especially (Fabricius) with the spread of pour-on formulation. The horn fly ，H. irritans is a target spe- Until Until now ， how ever ， no attempt has cies which is a blood-sucking pest of been made to evaluate the effect of this cattle. N. cornicina was chosen as non- drug on dung-breeding flies in Japan. target beneficial species which is common- The purpose of this study is to deter- ly found in dung pats as coprophagous in mine the effects of ivermectin residues in Hokkaido. Eggs of N. cornicina were col- dung voided by treated cattle on target lected from the surface of fresh dung pats and non-target dung-breeding 日ies in Hok- in pasture ，whi le eggs of H. irritans were kaido ， Japan. obtained by allowing gravid females to oviposit oviposit in test tubes (11 mm diameter X MA TERIALS AND METHODS 75 mm length). Thirty to 40 eggs in both species species were inoculated onto 30g of dung Cattle Cattle and dung collection in plastic cups (8 cm diameter X 4 cm The expe riments were conducted at the depth) doubled in large cups (1 2 cm diam- pasture pasture of Obihiro University of Agricul- eter X 5.5 cm depth) with sawdust for pupa- ture ture and Veterinary Medicine. Five Hol- tion site. These cups were maintained at stein stein cows (ages 31-53 months ) were sel- 25 0 C (1 6L-8D) and the number of pupae ected ected and ivermectin (l vomec ⑮ Topical; was counted . The pupae obtained were Merial Merial Limited) was topically treated to transferred to another plastic cup (8 cm them by pour-on formulation at the rec diameter X 4 cm depth) ， for adult eme r- ommended dose 500μg /kg body weigh t. gence . Experiments were replicated 3 Two treatments were don e on 25 May and times in H. irritans and 5 times in N. cor- 22 June in 2002 ，and at the same time eac h nzczna. 5 untreated cows (ages 45-52 months) were also selected and used as contro ls. Field e: ゅeγ iment: Eff ec ts 01 ivermectin on fiy None of the cows had been previously eme γge η ce treated treated with anthe lminti cs or insecticides Eighteen arti 白cial dung pats (1 kg ， three Dung pats were collected immediat ely pats each per collection date for treated after after defec ation at 1，3，7，14 ，21 ，28 and 35 and control) of 1，3，7 days after treatment days after treatments. 1n each collection ， were eac h placed on a 17 -cm layer of black dung pats from 5 cows were mixed and soil in a plastic box (33 X 33 X 19 cm). frozen frozen at - 20 0 C until used. Boxes with these dung pats were then placed placed in a fie ld area adjacent to a pasture for for exposure to insect activity for 7 days. Vo l. 56 No.3 2005 193 After After exposure ， these boxes were brought 7 days after treatment (Fig. 1) . Then ，iver- to to grassland in the campus of the Univer- mectin was detected in dung up to 14 sity sity and covered with emergence traps ( Exp. 1) and 21 days (Exp. 2) after treat- attached attached with cups for collection of ment ，and not detected at 28 and 35 days emerged f1 ies. Traps were checked every- after treatment; the determination limit day ，and f1 ies emerged from dung were was 0.002 ppm. collected ， counted and determined into the the species or families. These specimens Effects 01 ivermectin on pu ρα tion αnd α dult were dried in the laboratory more than e mergence 01 H. irritansα nd N. cornicina two months and their dry weights were Pupation rates of H. irrit α， ns in dung measured by an electric chemical balance from control cattle was from 64.4 to 100% (sartorius (sartorius B J1 500). These experiments at 1-35 days after treatment (Table 1) ， were performed two times in mid-June whereas they were zero in dung from tre and late July ，and a total of 36 dung pats ated cattle at 1 to 14 days ，17.9% at 21 was observed. days ，and 84.8 and 79.3% at 28 and 35 days after treatment ，respectively. Emer- RESULTS gence rates also showed the same tendency as the pupation rates. Determination Determination 01 ivermectin concentr α tions Pupation rates of N. cornicina in dung In In two treatments ， ivermectin residues from control cattle was from 86 .9 to 99.3% in in dung attained maximal concentrations at 1 to 35 days after treatment (Table 2). at at 3 and 1 days after treatments ，respec- On the other hand ， they were zero in dung tively ，and both peaks were followed by a from treated cattle at 1 to 14 da ys，about decline decline with below half concentrations at half (49 .8 % ) at 21 days ，and 95 .9 and 97.2% at 28 and 35 days after treatment ， 0.18 Experiment 1 respectively. Emergence rates also show- 0.16 ed the same tendency as that of pupation 0.14 rates.

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