FIMICOLOUS HISTERIDAE COLEOPTERA IN CAMPO GRANDE , MS , BRAZIL

Fecal masses recently excreted and/or almost dry were collected weekly in a pasture of Brachiaria decumbens Stapf, from May 1990 to April 1992. The feces were conditioned in 15-liter opaque plastic buckets, containing lateral and top openings, where flasks were fastened for capturing Histeridae beetles present in these masses. Three thousand two hundred ninety-nine specimens were collected belonging to 11 species in the Genus: Phelister, Hister, Euspilotus, Acritus, and Xerosaprinus. The most frequent, constant, and abundant species were Phelister sp. nr. carinifrons and P. haemorrhous.


INTRODUCTION
The action of parasites constitutes one of the factors negatively affecting the productivity and the efficiency of livestock industrialization.Some of the principal bovine parasites, such as the horn fly (Haematobia irritans L., 1758) and several species of gastrointestinal helminthes, grow in the feces of the host and/or have their free-life phase associated with these feces.Several species of flies characterized as important mechanical and biological vectors of pathogenic organisms for man and domestic animals also grows in bovine feces (Greenberg, 1971;Linhares, 1981;Lomônaco & Almeida, 1995).Flies like these represent a public health problem.
The systematic control of bovine parasites by chemical pesticides can result in the emergence of resistant populations (Bull et al., 1988;McKenzie & Byford, 1993;Cilek et al., 1995;Sheppard, 1995;Zizak et al., 1996) contributing to gradual loss of effectiveness of these products and elevation of pest control costs (Axtell, 1986).
In the fauna associated with bovine feces exist a great diversity of organisms.Among these, some aid regulating populations of other present arthro-pods; some who compete for food (feces); and still others that functioning as predators, parasites, or parasitoids.
The coleopterans of the Histeridae family are predators, as much in the young as in the adult phase.They prey on insects or small animals present in any substratum in decomposition (Arnett Jr., 1968).Geden & Axtell (1988) studied some species of Histeridae with a view to determining of the potential control that they exercise on the population of the domestic fly, Musca domestica.Summerlin et al. (1991), andFincher (1995) studied various species that act as predators of H. irritans.
In Australia, from 1969 to 1984, 57 species of coprophagous coleopterans and histerids were introduced.Thirty-nine were created in laboratory and liberated in the field, and 26 of them settled down in the continent (Tyndale-Biscoe, 1996).In the USA there is a similar program for evaluating the potential of foreign species possibly useful in horn fly control, including Histeridae species (Fincher, 1995).This author also reports an efficiency evaluation of the predation effects of Hister bruchi, a specie imported from Argentina that acts mainly on maggot and pupa of H. irritans.
With regard to predation of these coleopterans on fauna associated with bovine feces, available information in South America is still meager.Most existent reports concentrate on the initial stage: determination of the species present in feces (Flechtmann et al., 1995a, b, and c;Cabrera-Walsh & Cordo, 1997;Rodrigues & Marchini, 1998;Koller et al., 1999).
This research was carried out to determine the local histerid fimicolous species as well the relative abundance of each specie, and respective population dynamic.Such information would be useful to identify species potentially important in bovine parasite control.

MATERIAL AND METHODS
The experiment was carried out in the National Center of Beef Cattle Research (Embrapa Gado de Corte), part of the Brasilian Enterprise for Farming and Cattle-Raising Research (Embrapa), in Campo Grande, Mato Grosso do Sul State, Brazil (20º27'S and 54º37'W; Alt.530 m), from May 1990 to April 1992.This area is situated on the transition band of a wet mesothermical climatologic region (Cfa), with more than 30 mm of rain in the driest month, and the wet tropical region (Aw), with summer rainy season and winter dry season (Ometto, 1981).The pasture area (20 ha), predominantly of Brachiaria decumbens Stapf grass, was under permanent use with Nelore cattle (Bos taurus indicus).
Weekly between 8 and 9 a.m. three fecal masses (FM) were collected and brought to the laboratory.They showed humid to almost dry texture, as classified by Ávila & Fernández-Sigler (1988), or with ages two and/or three, as classified by Flechtmann et al. (1995c).
The FM were conditioned in 15-liter opaque plastic buckets with covers, measuring 20 cm of the base diameter and 30 cm of the top opening.The buckets contained an 8 cm layer of soil.A lateral opening was made on the top level of the soil layer, with a second opening on the top of the bucket cover.In those openings, dry flasks were positioned to capture the insects present in the FM.
The FM were maintained in the buckets for 40 days and the insects retained in the capture flasks were picked up twice a week.After that period, the soil and FM residue were removed from the buckets and remaining live or dead insects collected.The adult insects obtained were conditioned in flasks containing 70% alcohol until being identified.
The two species that presented, on a decreasing scale, highest values abundance, constancy, and frequency indexes were Phelister sp.nr.carinifrons, and P. haemorrhous.
In relation to the abundance index (Silveira-Neto et al., 1976)  The larger population levels of Histeridae were observed from October to May (Table 2; Fig. 1).That corresponds to the rainy season, and the annual period of higher average temperatures (October to April), except for May, which begins, in the study area, the dry season of the year (May to September) (Fig. 1).
The results showed that Phelister sp.nr.carinifrons and P. haemorrhous had the largest abundance, constancy, and frequency indexes, which should be considered in either a control program or integrated management of bovine parasites associated with bovine feces.
In the first year of this experiment, the histerid population was higher than in the second year, and the population level showed a tendency to follow precipitation (Fig. 1).Thus, the lower number of histerids in the second year would result from less rain.
The period from June to September corresponds in the study area to the driest period of the year, at which time native species of observed Histeridae show reduced their population levels, which drastically decreases predation activities.Thus, species with less moisture dependence, among other characteristics, constitute preferential candidates in programs of Histeridae introduction which seek to further biological control of pests associated with bovine feces.Identifying ecological parameters of the most numerous local species may help in making decisions on introducing other species.This will contribute to natural control of these pests in periods when native histerids become rare.
Recently, several authors (Fincher, 1992;McCracken, 1993;Wiktelius, 1996;Bianchin et al., 1997Bianchin et al., , 1998) ) have called attention to the presence of pesticides in fecal residues of treated animals.Such residue act deleteriously on fimicolous organisms, possibly causing mortality among useful biological control agents.The frequent exposure of their enemies to residue or to low concentrations of the pesticides designed to eliminate them, as is happening in the case of bovine feces, contributes to the process of selection of individuals resistant to such products.
Global attention is gradually the awakening to the importance of reducing, to the minimum possible, pesticide use and residual levels acceptable in foodstuff so as to protect the environment and food supply.Additional pressure has been exercised by the high costs associated with pesticide use.Therefore, research must address identification and adoption of integrated pest management practices, including control of organisms considered pests through the use of their natural enemies or competitors.

Fig. 1 -
Fig. 1 -Monthly total of specimens of histerids captured, and meteorological records (total monthly precipitation and average temperature) in Campo Grande, Mato Grosso do Sul State, Brazil, from May 1990 to April 1992.