Life-History of the White Mealy - Bug Ferrisia virgata (CKLL.) (Homoptera, Pseudococcidae)

Abstract

Five generations of Ferrisia virgata (CKLL.) have been reared per year; singly on sprouting potato tubers, although the fifth generation was not completed because of cold weather. This method produces only parthenogenic females, while males and females may be produced by dense rearing. Copulation was never observed, while oviposition behaviour and hatching process were described. Eggs are deposited singly and the incubation period averages 2.11–2.62 hr. with no significant difference under various thermal conditions. Hatchability ranges from 96.2–99.1%. Total nymphal duration in females averages 43.2 and 92.6 days at 28.9 and 16.6°C., respectively, while that in males elapses 25.4 days at 25.1–26.5°CC. Duration of the three nymphal instars of females and the four ones in males are estimated in various generations. The differences in duration between generations and those between instars within each generation were highly significant. Rate of mortality during nymphal stadia in the autumn/winter generations is higher than that in the spring/summer ones; being 14.3–100 and 0–23%, respectively. Longevity of parthenogenic ovipositing and non-ovipositing females as well as that of males is estimated. The total life period (from egg to adult death) averages 76.2–154.6 days in females opposite to 19–47 in males. Eggs laid by a female averages 64.1–78 eggs; producing 61.6–67.6 nymphs/female/life. Average number of eggs/female/day averages 3.4–4.5 eggs. Three hymenopterous parasites and five predators are found associated with F. virgata. However, numbers of these bioagents are considerably low compared to the relatively high population of the pest.