Ontogenesis, transfer and repair of mouthpart deformities during moulting in Chironomus riparius (Diptera, Chironomidae)
Vermeulen, Angelo C.; Liberloo, Gwenny; Ollevier, Frans; Goddeeris, Boudewijn
Archiv für Hydrobiologie Volume 147 Number 3 (2000), p. 401 - 415
published: Feb 3, 2000
ArtNo. ESP141014703006, Price: 29.00 €
Ontogenesis, transfer and repair of larval chironomid deformities during moulting are described for the first time. Third instar Chironomus riparius larvae from a contaminated stream were individually reared to fourth instar in the laboratory. Mentum and mandible deformities present in the third instar exuvial head capsule were then compared with deformities in the fourth instar larva. Instar IV larvae displayed higher deformation frequencies than instar III larvae. The majority of the deformities in instar III were identically passed on during moulting. Partial and complete repair occurred to some extent, indicating that chironomid mouthpart deformation can be reversible. The frequency of deformed instar III larvae gaining additional deformities after moulting, was equal to the frequency of normal larvae with deformities after moulting. This shows that the presence of deformities does not increase the susceptibility for the formation of new deformities. The effects of physical tooth damage on the formation of mouthpart deformities was also investigated, but no relationship was found between tooth breakage/abrasion and deformation. The difference in deformation frequency between instar III and IV larvae once again stresses the importance of separate screening of different instars for biomonitoring and toxicity testing purposes.