REPRODUCTION, SURVIVAL RATE AND LONGEVITY OF APTEROUS PARTHENOGENETICFEMALES OF PEA APHID, ACYRTHOSIPHON-PISUM (HARRIS) (HOMOPTERA, APHIDIDAE), ON CHEMICALLY-DEFINED ARTIFICIAL DIETS WITH DIFFERENT SUCROSE CONCENTRATION AND PH

Apterous parthenogenetic females of the Pea Aphid collected in the Tok achi district of Hokkaido Island (Tokachi strain) were reared on chemi cally-defined artificial diets with different sucrose concentration an d pH (25-55 g/100 mi, PH 6-10), after two days of reproduction on broa d-bean seedlings, Vicia faba L., at 15 +/- 1 degrees C, under 16L:8D. Survival rate, longevity and the number of offspring per aphid were ma ximum when reared on a diet of 45 g/100 mi sucrose concentration and p H 8.3. The survival rate (75%) at the 10th day of rearing and the mean longevity (17.8 +/- 2.0 days) of the aphids on the best artificial di et were not significantly different from the values for aphids reared on broad bean (85.7% and 20.5 +/- 1.7 days, respectively). The mean nu mber of offspring (32.0 +/- 2.4) per diet-reared aphid was 45.3% of th e value for aphids reared on broad bean. In our experiments, the best combination of sucrose concentration and pH for the artificial diet fo r the Pea Aphid (Tokachi strain) is different from the results of Akey and Beck (1972) for the same species (Wisconsin strain). This indicat es that there are variations in optimum sucrose concentration and pH f or artificial diet between aphid strains.