LONG-TERM EFFECTS OF HEAVY-METALS IN FOOD ON DEVELOPMENTAL STAGES OF AIOLOPUS-THALASSINUS (SALTATORIA, ACRIDIDAE)

Newly hatched F1 nymphs of Aiolopus thalassinus (Fabr.) were fed on food treated with various concentrations of HgCl2, CdCl2, and PbCl2 until the end of adult life. Toxicological observations were followed in the F1 generation and in the F2 generation derived from the heavy metal-loaded F1 parents. The highest concentration of the heavy metals caused 100% mortality of the F1 adults within four weeks. The nymphal duration of the F1 and F2 generations was significantly prolonged after Hg and Cd exposure, but the F1 of the group treated with lead was not affected. The fresh body weight of adults was significantly reduced in the F1 generation of most treatments and in the resulting untreated F2. The lifespan of the F1 adults was shortened. In the F2 generation, although the lifespan was somewhat longer, generally it was still shorter than that of the control adults. The mean egg number laid by F1 adults fed on food contaminated with Hg or Cd was decreased. This decrease was more pronounced in the case of Cd than Hg. In the females fed on food treated with Pb the reduction of the number of egg pods was not remarkable. The hatchability of the eggs laid by F1 females was significantly reduced as compared to the control. The viability of the eggs laid by F1 adults was somewhat decreased due to either a reduced number of egg pods or to a lower rate of hatchability, especially in the case of Cd. The treated adults frequently displayed weakness in their legs, difficulties in walking, tremors, and nervous movements. In 1% of the F1 adults, the wings were abnormally developed being outstretched and bent downward. The last instar nymphs hatching from eggs laid from F1 adults in PbCl2-treated soil failed to moult to adults.