Development Rates of Some Finnish Gerris Fabr. Species (Het. Gerridae) in Laboratory Cultures

摘要: Abstract Egg and larval development times of Gerris odontogaster (Zett.) (COD), G. lateralis Schumm. (LAT), lacustris (L.) (LAC), thoracicus (THO) rufoscutellatus Lt. (RU) were studied. In species OD they are dependent on temperature. The roles photoperiod, crowding food remain open, even if continuous light seems to have a retarding effect the LAC. subsequent instars OD, LAT LAC shown be unequal lengths. When rates different compared in 25―26°C, sequence from fastest slowest was LAT, THO, LAC, RU, i.e., disregarding RU just opposite order experienced nature Finland. This raised question why not displaced microclimatically warmest habitats. answer is supposed lie seasonal, environmentally determined alary dimorphism which adapts it better than other warm but at same time temporary