Physiology of diapause in the adult Colorado beetle (Leptinotarsa decemlineata Say)—I The photoperiod as a controlling factor

Population dependent effects of photoperiod on diapause related physiological traits in an invasive beetle (Leptinotarsa decemlineata)

“…The growth pattern results might be partially confounded by differences in voltinism between the populations. The northern population (Petroskoi) is most likely univoltine, while middle European populations have been reported to be bivoltine (de Wilde et al 1959). Since development time can change depending on generation in multivoltine species (see Abrams et al 1996), it is possible that the shortest photoperiods used in Study I and the 12 hour photoperiod in Study V might be interpreted as spring, rather than autumn, in the populations from Emmen and Belchow.…”

“…L. decemlineata is a holometabolous oligophagous herbivore which overwinters in diapause. New adults emerging from pupae during the summer decide whether they will reproduce, migrate or overwinter depending on environmental cues, most notably the photoperiod (de Wilde et al 1959). Reproductive maturity is reached within one week after eclosion, after which adults mate and females lay eggs, in batches of up to 100 eggs on the underside of potato leaves.…”

“…Prolific research done in the former USSR, the Netherlands and North America during the latter half of the 20 th century has established the basic framework of diapause induction in this species (Danilevski 1965, Tauber et al 1986, de Kort 1990. Diapause is driven by short photoperiods experienced by the adult beetles shortly after eclosion (de Wilde et al 1959) although it is positively influenced by low temperature and shortage of food (de Kort 1990). There is population dependent variation in critical photoperiod (CPP) (when 50 % of mature adults initiate diapause), but evidence for the extent of photoperiodic adaptation is not conclusive (de Wilde et al 1959, Danilevski 1965, Tauber et al 1988.…”

“…Diapause is driven by short photoperiods experienced by the adult beetles shortly after eclosion (de Wilde et al 1959) although it is positively influenced by low temperature and shortage of food (de Kort 1990). There is population dependent variation in critical photoperiod (CPP) (when 50 % of mature adults initiate diapause), but evidence for the extent of photoperiodic adaptation is not conclusive (de Wilde et al 1959, Danilevski 1965, Tauber et al 1988. Adult beetles destined for diapause normally migrate to the sides of potato fields, or into neighboring forest patches, where they burrow into the soil, to depths between 20 and 80 cm , Milner et al 1992).…”

“…At around 10 days after adult emergence L. decemlineata are physiologically ready for diapause (de Wilde et al 1959, Piiroinen et al 2011) and therefore differences between photoperiods and populations should be manifested at this age. Additionally, in several studies a subsample of beetles was allowed to overwinter.…”