Response of horse flies (Diptera, Tabanidae) to ...

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HRIBAR et al., 1992; SCHRECK et al., 1993; HAYES et al., 1993; NILSSEN, .... Also, HAYES et al. (1993) showed that .... Eddie A. UECKERMANN. Lubomir ...
Biologia. Bratislava, 60/5: 611-613,2005

611 SHORT COMMUNICATION

Response of horse flies (Diptera, Tabanidae) to different olfactory attractants Stjepan

KRCMAR

Department of Biology, Faculty of Philosophy, J.J. Strossmayer University, L. Jagera 9, HR-31000 Osijek, Croatia; e-mail: [email protected]

Abstract: The attraction of female horse flies to unbaited and single baited Malaise traps using 1-octen-3-01, acetone and ammonium hydroxide was studied in Eastern Croatia. Horse flies were collected in significantly higher numbers in l-octen­ 3-01 baited traps than in traps baited with acetone, ammonium hydroxide or traps without these substances. The number of females of Haematopota pluvialis, Tabanus bromius, Tabanv.s macv.licomis and Chrysops relictv.s collected from 1-octen-3-o1 baited Malaise traps and traps with other attractants differed significantly compared with controls. Females of Hybomitra bimaculata were also collected more frequently in 1-octen-3-o1 baited Malaise traps than in traps with acetone but this difference was not significant. Finally, the octenol baited Malaise traps collected 21 times more horse flies than unbaited traps, while acetone and ammonium hydroxide baited traps collected eight and four times as many flies, respectively than unbaited traps. Octenol appeared to be a very effective attractant for horse flies in Eastern Croatia. Key words: Tabanidae, attractant, Malaise traps, Croatia.

Introduction Attractants can increase the effectiveness of traps for collecting haematophagous Diptera. For example, the efficacy of tabanid traps has been shown to be in­ creased by the addition of carbon dioxide (ROBERTS, 1971, 1975; DOSKOCIL & CHvALA, 1974) and octenol (l-octen-3-ol) (LONG & FRENCH, 1988; FRENCH & KLINE, 1989). Indeed, adding ammonia to octenol has elicited similar increases (FRENCH & KLINE, 1989; HRIBAR et al., 1992; SCHRECK et al., 1993; HAYES et al., 1993; NILSSEN, 1998; KRISTENSEN & SOMMER, 2000). However, while some authors have reported in­ creased catches (JAENSON et al., 1991; PHELPS & HOL­ LOWAY, 1992; SCHRECK et al., 1993; HAYES et al., 1993; FOIL & HRIBAR, 1995; FRENCH & HAGAN, 1995; NILSSEN, 1998), LEPRINCE et al. (1994) found no such effect. Differential response to various olfactory attrac­ tants probably occurs among the genera and species of Tabanidae. Therefore, a field study was conducted to evaluate Malaise traps baited with either acetone, ammonium hydroxide, or l-octen-3-ol for their attrac­ tiveness to horse flies in E Croatia.

white willow, black poplar and common oak with individ­ ual trees as tall as 7-8 m. Horse flies were collected with four modified linen Malaise traps (TOWNES, 1962) baited with acetone, 1-octen-3-01, or ammonium hydroxide solution in the period from May to late August in 2001 and 2002. Malaise traps were placed along forest transects about 500 m apart and were not visible from one site to the next. Attrac­ tants were rotated among traps every day. There was always one Malaise trap without attractant serving as a control. Sampling was carried out during 33 field trips lasting about 12 h each. Fresh attractants were placed at the beginning of each trapping period. Each time, traps were filled separately with 4 ml 1-octen-3-01, 30 ml acetone and 30 ml ammonium hydroxide. Attractants were dispensed from glass vials with Styrofoam corks. A 10 cm long cotton wick protruded from the centre of the cork to the outside. Vials were placed 50 cm bellow the top of the Malaise traps. The trapping period was between 7 a.m. to 7 p.m. All trapped flies were preserved in ethanol. Identification and nomenclature followed CHvALA et al. (1972) and CHvALA (1988). Nearly all collections were made under ideal weather conditions without strong wind; the minimum air temperature was recorded on each day at 8 a.m. and the maximum around 4 p.m. The relative hu­ midity ranged from 40 to 90%. Responses of horse flies to attractants were tested by X2 analysis using the five most abundant species from the collections.

Material and methods

Results

This study was conducted in the Monjoros Forest (45° 45'20" N, 018°52'11" E), approximately 2 km NE from the Nature Park Kopaeki rit in E Croatia. The forest is composed of

A total of 2,126 specimens was collected belong­ ing to 17 species of horse flies grouped into the

612

S. KRCM.

Table 1. Horse flies collected by Malaise traps baited with 1-octen-3-ol, acetone, ammonium hydroxide, and unbaited control traps Species Chrysops caecutiens (L., 1758) C. relietus Meigen, 1820 C. viduatus (F., 1794) Atylotus loewianus (Villeneuve, 1920) A. rusticus (L., 1767) Hybomitra bimaculata (Macquart, 1826) Hy. ciureai (Seguy, 1937) Hy. muehlleldi (Brauer, 1880) Hy. solstitialis (Meigen, 1820) Tabanus bromius L., 1758 T. maculicornis Zetterstedt, 1842 T. sudeticus Zeller, 1842 T. tergestinus Egger, 1859 Haematopota italica Meigen, 1804 H. pandazisi (Krober, 1936) H. pluvialis (L., 1758) H. subcylindrica Pandelle, 1883

Attractant totals

l-octen-3-ol

Acetone

NH40H

4 67 8 18 2 95 20 1 4 324 94 30 37 6 1 577 32

0 41 11 7 0 91 6 0 1 129 23 25 5 6 1 148 7

0 12 8 1 1 12 1 0 0 59 13 11 4 4 0 114 2

501

242

1320