Critical photoperiod inducing diapause in the western tarnished plant bug (Lygus hesperus) from Arizona

In spite of the economic importance of the western tarnished plant bug, Lygus hesperus, in the western U.S., key aspects of its biology remain poorly investigated.  Among those aspects is the dynamics of photoperiodic induction of diapause.  Developing L. hesperus were exposed to a range of photoperiods and the presence of diapause was determined by dissection of adults.  The diapause response to photoperiod was then described by a logistic function.  The critical photoperiod (corresponding to 50 percent diapause) differed between male and female L. hesperus.  Furthermore, fewer males than females entered diapause regardless of daylength.  The overall diapause response of these populations originating in Central Arizona was substantially lower than that previously reported for L. hesperus in California, suggesting differences in the diapause response between populations.  Results also suggest that a population specific critical photoperiod (corresponding to 50 percent of the maximal diapause response) may be useful in additional studies to determine how other factors, such as temperature, interact with photoperiod to influence diapause induction.