The influence of photoperiod upon the productivity of Oryzaephilus surinamensis (L.) (Coleoptera: Silvanidae)

An increase in illumination intensity to 700-800 lx suppressed the productivity of additional strains, including the Tangmere strain in LD 12:12. However, an intermediate level of productivity was observed in several of these strains in constant light at this intensity. Therefore, the productivity of the Tangmere and Thorne strains was assessed during the scoto- and photophases at this increased illumination intensity. Preliminary experiments indicated that the disturbance associated with the experimental method also suppressed productivity over a 12-h cycle. Therefore, an artificial photoperiod of LD 24:24 was used to minimise this effect after a 3-week entrainment period. The productivity of both strains was greater in the scotophase than in the photophase and suggests that the suppression of productivity in LD 12:12 was associated with the difference between the phases of this photoperiod.