Both Scymnus syriacus Mars. and Scymnus levaillanti Muls. are aphidophagous coccinellids. In the laboratory they consumed and successfully reproduced on several species of aphids. Larvae suck the prey contents from aphid appendages, while adults consume the whole aphid, except for parts of the appendages. Extra-oral digestion is practiced during feeding. The mean number of aphids consumed by the larval stage of S. syriacus when reared at 25°C was 95, and 130 aphids at 30°C. For S. levaillanti it was 125 and 139 aphids at 25°C and 30°C, respectively. The mean number of eggs deposited daily by S. syriacus for the first three weeks of adult life was 19.5, with a range of 3-30 eggs at 25°C. Longevity of adults ranged from 3 to 4 months at 25°C and 2.5-3 months at 30°C.
The study was performed to test the hypothesis that winter food deficit can act to reduce a water vole, Arvicola terrestris, population in Western Siberia. During 12 years, a total of 139 wintering burrows were examined at different phases of population cycles. The size of food stores was found to be greater during increases of the population compared to that at the peak and the decline. Comparison of the mass of stores in burrows and the daily consumption of natural foods under controlled conditions shows that only a small fraction of individuals have sufficient food supply for safe wintering. Females have smaller stores compared to males, and this is possibly responsible for their higher winter mortality. The size of food stores in October affects both winter change in body mass as defined by difference between average mass in samples of animals captured in October and in May of the next year and winter survival determined as a ratio between population densities in May and October. The deficiency of food during winter is likely to be a strong factor affecting body mass change, density, sexual and age structures, and reproductive potential in the water vole population in Western Siberia.
One factor limiting the adoption of aphidophagous coccinellids in augmentative biological control is cost-effective mass production. The use of factitious foods may lower production costs by reducing space and manpower requirements for mass rearing of the predator and its prey and by enhancing mechanization of rearing procedures. The objective of this study was to compare the efficiency of food conversion, consumption indices and growth rates of first to fourth instars of Adalia bipunctata when fed either a mixture of Ephestia kuehniella eggs and fresh bee pollen, or on the natural prey Myzus persicae. Larval survival did not differ among treatments, averaging 80 and 90% on the respective diets. Mean dry body weights of the coccinellid were significantly lower on M. persicae than on the factitious food only for second instars and the pre-pupal stage. Dry food consumption by the predator throughout larval development averaged 20.61 mg on factitious food and 14.82 mg (corresponding to an average of 284 third and fourth instars) on M. persicae. The efficiency of conversion of ingested food for total larval development averaged 25 and 30% on factitious food and aphids, respectively. The relative growth rate of the larval instars was higher on aphids, whereas the consumption index was higher on the mixture of E. kuehniella eggs and pollen. An additional experiment showed that rearing the previous instars on the factitious food had no substantial effect on aphid consumption in the fourth instar. The study suggests that this factitious diet may be an appropriate food source for mass rearing A. bipunctata.
Species in the carnea complex of the common green lacewing are predators of the common pistachio psylla, Agonoscena pistaciae in both cultivated pistachio plantations and on wild pistachio plants in Iran. The seasonal occurrence of common green lacewings was monitored in pistachio orchards from 2007 to 2008. In addition, the effect of different temperature regimes on preimaginal development, survival and prey consumption of the predatory lacewing Chrysoperla lucasina fed on A. pistaciae nymphs were studied under controlled conditions. The adults of common green lacewings first appeared on pistachio trees in mid April and were most abundant in early July, decreased in abundance in summer and increased again in October. The relative density of common green lacewings was higher in pistachio orchards where the ground was covered with herbaceous weeds than in those without weeds. In the laboratory females of C. lucasina laid an average of 1085 eggs over 60 days at 22.5°C. The maximum prey consumption occurred at 35°C when the larvae consumed 1812 fourth instar psyllid nymphs during their larval period. The intrinsic rate of natural increase (rm) was 0.11. The total development (egg-adult) required 385 degree-days above the theoretical lower developmental threshold of 9.6°C. and Fatemeh KAZEMI, Mohammad Reza MEHRNEJAD.