Influence of photoperiod on development and maturation of Macrolophus pygmaeus (Hemiptera, Miridae)

Abstract

The effects of day length on development and reproductive maturation of zoophytophagous bug Macrolophus pygmaeus (= M. nubilis) were investigated under laboratory conditions using two strains originated from the environs of Rome, Italy (41.75°N, 12.30°E and 41.95°N., 12.80°E) and Sochi, Krasnodar Territory, Russia (43.9°N, 39.3°E). The insects were kept under day length of either 10 or 16 h at a constant temperature of 20°C. Nymphs and adults were fed on the grain moth eggs. Embryonic development lasted 18–20 days, nymphal development, 25–30 days, and reproductive maturation of females, 4–6 days. The short day length (10 h) resulted in 1–2-day prolongation of nymphal development and a longer maturation time in individuals from both strains, whereas the duration of embryo development was independent of photoperiod. Under both photoperiods, males developed faster than females. Under the short day length, females of the Rome strain matured markedly faster than those of the Sochi strain. Faster development under low temperature and stronger tendency to delay the reproductive maturation observed in the Sochi strain could be explained by a relatively fast (when compared with Rome) autumnal decrease in temperature. The mechanism and adaptive value of the long-day acceleration of development are not yet clear.