Arthropods from fallow land in a winter wheat-fallow sequence.
Abstract
Over a period of 4 years, insects emerged throughout the year from the uncropped area in a winter-wheat-fallow sequence on Rothamsted Farm, southern England [cf. preceding abstract]. After harvest, many Diptera and Hymenoptera were caught in the emergence traps, but the numbers varied between 1970 and 1974. In 1970, Phoridae, Sciaridae and Cecidomyiidae were common; in 1971, Lonchoptera lutea Mg. and Scaptomyza pallida (Zetl.) (Parascaptomyza pallida) were also numerous, as were such hymenopterous parasites as Cyrtogaster vulgaris Wlk., Callitula bicolor Spin. Asaphes vulgaris Wlk. and Braconidae. After straw burning in September 1972, few insects emerged, and in 1973 there were many springtails. In 1974, it was very wet and the ground waterlogged so the traps were in position for a shorter time and little was caught.After ploughing and during the winter months of all years except 1973, Smittia aterrima (Mg.), Trichocera regelationis (L.), Bradysia sp. and a few cecidomyiids were caught as well as dark forms of L. lutea. As temperatures rose and days lengthened, the catches became more diverse with sphaerocerids, phorids and many species of Cecidomyiidae.During the summer months, empidids, such as Tachydromia arrogans (L.) and several species of Platypalpus, appeared. Again, there was variation between the years; more species were caught and the index of diversity was greater in 1971 than in any other year; fewest were caught in 1973. Sitona lineatus (L.) hibernated in the soil, several examples being caught in 1971, fewer in 1972, none in 1973 and only one in 1974.The decaying remains of the wheat crop afforded food and shelter for the larvae of many insect species. After straw burning, the numbers and diversity of the catch were much reduced. Many spiders were caught in the cages but their origin is uncertain.