This Article Full Text (PDF) References Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Saved Citations Download to citation manager Request Permissions Request Reprints Add to My Marked Citations Citing Articles Citing Articles via Google Scholar Citing Articles via Scopus Google Scholar Articles by Wassmer, G. T. Articles by Page, T. L. Search for Related Content PubMed PubMed Citation Articles by Wassmer, G. T. Articles by Page, T. L. Social Bookmarking                         What's this?

Photoperiodic Time Measurement and a Graded Response in a Cockroach

Department of Biology, Vanderbilt University, Nashville, Tennessee 37235

Terry L. Page

Department of Biology, Vanderbilt University, Nashville, Tennessee 37235

Almost exclusively, photoperiodic insects respond to a given photoperiod in one of two ways: a "long-day" response or a "short-day" response. Intermediate responses occur only at a very restricted range of photoperiods (often less than 30 min) and are generally population phenomena rather than intermediate responses of individuals. In contrast, individuals of the wood roach, Parcoblatta pennsylvanica, show intermediate responses over a broad range of photoperiods.

We examined the effect of constant light, constant darkness, and photoperiods ranging from 10 to 18 hr of light per 24 hr on growth rate as measured by weight gain, and found a robust photoperiodic response. Nymphs raised in photoperiods with light periods (photophases) from 0 to 12 hr gained little weight, whereas those in LD 18:6 were almost 15 times heavier. This is the first report of a photoperiodic response curve for a cockroach. Interestingly, there was a linear relationship between the duration of the photophase and weight gain over a broad range of photoperiods (LD 12:12 to LD 18:6; r² = 0.99). Statistical analysis showed that the intermediate responses were attributable to individuals' growing at an intermediate rate. Another interesting observation was that all larval stages appeared to be capable of perceiving and responding to photoperiodic signals. The results of further experiments using non-24-hr photoperiods were consistent with the existence of a circadian component in the photoperiodic time measurement in this species.

Key Words: photoperiodism • circadian rhythms • graded response • cockroach

Journal of Biological Rhythms, Vol. 8, No. 1, 47-56 (1993)
DOI: 10.1177/074873049300800104


CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?