Effects of the Carbamoyloxime, Aldicarb, On the Ultrastructure of the Root-Lesion Nematode, Pratylenchus Penetrans (Nematoda: Pratylenchidae)

Adult female P. penetrans were incubated in 1, 5 and 10 ppm aldicarb for 1, 12 and 24 h at 7°C and processed for transmission electron microscopy either directly or following 36 h incubation in artificial tapwater (ATW). All treatments, except exposure to 1 ppm aldicarb for 1 h, induced increased densities of β-glycogen granules in non-contractile portions of muscle cells. 'Vacuoles', probably representing leached, saturated lipid droplets, were present in the cytoplasm of several cells after exposure to 5 ppm aldicarb for 24 h and 10 ppm for 12 and 24 h. At these concentrations and exposure times, internal dendrite terminals within the amphidial sheath cell processes hypertrophied. Two further effects observed in specimens treated with 10 ppm aldicarb for 24 h were the presence of large, electron-lucent granules in the amphidial sheath cell cytoplasm and denaturation of sarcoplasm of somatic muscle cells and anterior attachment processes of stylet protractor muscles. With the exception of β-glycogen granule densities, none of these effects was reversed by 36 h incubation in ATW. The significance of these findings and the mode of action of aldicarb at these concentrations are discussed in the light of earlier behavioural studies.