The acoustical behavior of Acheta domesticus L. (Orthoptera: Gryllidae) following sublethal doses of parathion, Dieldrin and Sevin

Prolonged effects of the insecticide dimethoate on locomotor behaviour in the woodlouse, Porcellio scaber Latr. (isopoda)

: Beneficial invertebrates living in hedgerows and woodland adjacent to arable land, are almost inevitably exposed to small doses of pesticides. This can present a threat to these invertebrates even at sublethal levels. Locomotor behaviour is intrinsic to many more complex behavioural responses such as predator avoidance, migration, mate seeking, etc., but is also closely related to the physiological status of the animal. Further, locomotor activity is quantifiable with the aid of modern video and computer technology. In the present study, the effect of a 48 h exposure of the woodlouse Porcellio scaber to soil contaminated with one-tenth of the LD20 (96 h) dimethoate dose was quantified using computer-automated video tracking. Dimethoate-exposed woodlice were recorded for one night prior to dimethoate exposure and for two nights on contaminated soil. After a recovery period of 21 days, the woodlice were recorded for a further night. Control animals were recorded in parallel on soil treated with water. Over the 48 h of exposure, dimethoate induced a gradually increasing hyperactivity in terms of time spent in activity, mean velocity and path length and a suppression of turning rate when compared with controls. No recovery was seen after the 21 days on uncontaminated soil. These effects were statistically significant only in male woodlice.

The role of biomarkers in environmental assessment (5). Invertebrate populations and communities

Although a number of biomarkers of pollutant exposure have been identified in invertebrate species, direct linkage with changes at population and/or community levels are poorly documented and, despite the ecological importance of invertebrates, there is no conclusive evidence that individual measurements of biochemical parameters may allow the effects of pollutants on populations and communities to be predicted. Among the various biochemical parameters used as biomarkers in invertebrates exposed to pollutants in the field, only those for which changes at population or community level can be suggested are discussed in the present review. At population and community levels, the development of resistance to pesticides and changes in behaviour, reproduction and development are analysed as putative consequences of biochemical and physiological alterations. Limits to the use of biochemical parameters as biomarkers of invertebrate exposure to pollutants are discussed. Future research trends and experimental approaches to the validation of invertebrate biomarkers in environmental pollution assessment are suggested.