Studies on low temperature survival, reproduction and development in scottish clones of Myzus persicae (Sulzer) and Aulacorthum solani (Kaltenbach) (Hemiptera: Aphididae) susceptible and resistant to organophosphates

Abstract

AbstractInvestigation of 16 Scottish clones of Myzus persicae (Sulzer) and four of Aulacorthum solani (Kaltenbach) indicated that anholo-and androcyclic clones were predominant. A high incidence of organophosphorus resistance was found in androcyclic clones of M. persicae, but there was no indication of such resistance in A. solani. At 5°C as compared to 20°C, reproduction was decreased and development of nymphs was slower in both species. In addition, the pre-reproductive period and nymphal development time of A. solani were longer than those of M. persicae. Clonal differences in M. persicae at 5°C could not be related to origin, annual cycle or level of organophosphorus resistance, however A. solani clones from the west of Scotland may have been less affected by this temperature than those from the east. The lower limit of reproduction and development in both species was near 2°C. Neither adult survival nor fecundity of clones at this temperature were related to annual cycle, origin or organophosphorus resistance, but anholocyclic M. persicae nymphs survived longer at 2°C than holo- or androcyclic nymphs. A. solani adults survived significantly longer than those of M. persicae. M. persicae survived sub-zero temperatures better than A. solani. In neither species could percentage survival be related to stage of development, gut contents, presence or absence of wings, annual cycle, origin or organophosphorus resistance. Acclimation did, however, increase percentage survival.