Influence of temperature, photoperiod and host‐plant on the bionomics of the melon ladybird Epilachna chrysomelina (F.) (Coleoptera: Coccinellidae)

The effect of controlled temperatures: 20, 25 and 30°C ± 1°C combined with photoperiods of 14/10 and 10/14 h light/ dark, and four different host plants (cucumber, snake cucumber, squash and watermelon) on the rate of development, duration of generation, mortality rate and fecundity of Epilachna chrysomelina was experimentally studied. Temperature and photoperiod considerably affected the hatchability percentages of eggs, larval and pupal periods, duration of generation and rate of mortality. No effect was however observed on the incubation period, pre‐oviposition period or sex ratio. A temperature of 25°C ± 1°C combined with 14 h photophase proved to be the most favorable for the insect development. On snake cucumber, development was faster, females were more fecund and mortality rate was extremely low as compared with other foods. On cucumber, development was retarded, survival rate reduced and fecundity of females lowered. There seems to be a negative correlation between crowding of adults and female fecundity; the higher the density, the lower the number of eggs produced. Über eine mögliche genetische Komponente bei der Anpassung von Myzus persicae (Sulz.) (Hom., Aphididae) an synthetische Nahrung Von 64 Myzus‐persicae‐Klonen konnten 57 nur bis maximal zur 3. Generation bei künstlicher Nahrung am Leben erhalten werden, ganz im Gegensatz zu früheren Experimenten. Zwei Generationen erreichten die 4. Generation und 5 gingen darüber hinaus. Letztere befanden sich zum Zeitpunkt dieser Niederschrift bereits in der 10. Generation. Hinweise führen zu der Ansicht, daß die Klone in ihrer Fähigkeit, mit einem noch unbekannten Mangelfaktor in der synthetischen Nahrung fertig zu werden, sich genetisch unterscheiden. 1981 Blackwell Verlag GmbH