Premium
Spatial distribution of bibionid larvae in agricultural grassland
Author(s) -
Blackshaw R.P.,
D'ArcyBurt S.
Publication year - 1997
Publication title -
entomologia experimentalis et applicata
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.765
H-Index - 83
eISSN - 1570-7458
pISSN - 0013-8703
DOI - 10.1046/j.1570-7458.1997.00193.x
Subject(s) - grassland , larva , biology , spatial distribution , population density , population , ecology , remote sensing , geography , demography , sociology
Abstract The distribution of bibionid larvae in agricultural grassland was investigated. They tend to occur sporadically and at low population density. More detailed sampling within a field showed that numbers were highest adjacent to a hedgerow with most being found 6–11 m from the hedge. Log variance/log mean relationships were established for counts of Bibio johannis and Dilophus febrilis larvae collected from soil cores in grassland. Both species were highly aggregated. An area of grassland ( 160 cm × 80 cm ) was divided into 128 soil blocks and B. johannis larvae extracted. Almost all larvae were associated with aggregations. The two‐phase mozaic method of Pielou (1974) was applied to larval counts from different sized concentrically collected soil cores. Larval patches were not randomly distributed. Time‐lapse video studies of bibionid larvae were made and showed both aggregation and processional behaviour. This was associated with chemical stimulation which is probably used to maintain larval groupings in the field. There was evidence for two levels of aggregation. The first is due to groups of larvae arising from eggs laid by a single female and the second, larger scale, aggregation is due to factors that influence the distribution of adult flies.