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1 March 2006 Photoperiodic Induction of Reproductive Diapause in the Predator Geocoris uliginosus (Hemiptera: Geocoridae)
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Abstract

The critical photoperiod for diapause induction in the predator Geocoris uliginosus (Say) and the stage/instar(s) sensitive to diapause-inducing photoperiods were determined in the laboratory. Six photoperiods were used for the critical photoperiod experiment (all at 24 ± 1°C): 10:14, 11:13, 12:12, 13:11, 14:10, and 15:9 (L:D) h. The critical photoperiod was ≈13.2 h of light d−1. At 12:12 and 11:13 h, 86–88% of the population entered diapause, whereas 20% or less entered diapause at longer daylength. To determine the stage/instar(s) sensitive to diapause-inducing photoperiods, cohorts of bugs were reciprocally switched between two photoperiods, 15:9 (not diapause-inducing) and 11:13 h (diapause-inducing), at the beginning of the second, third, fourth, and fifth instar, and at the beginning of the adult stage. A given cohort was switched only once during the experiment. Two additional cohorts were reared as controls under the respective photoperiods with no switching throughout the experiment. Exposure to diapause-inducing photoperiods from the beginning of the fifth instar through the adult stage induced reproductive diapause in 100% of the females in this experiment, whereas exposure from the beginning of the adult stage induced only 42% diapause. Thus, when daylength shortens to the critical photoperiod in late summer, most individuals that are in the nymphal stage will subsequently enter reproductive diapause, whereas a majority of those that have reached the adult stage by that date will reproduce.

Sonja L. Brannon, Kimberly B. Decker, and Kenneth V. Yeargan "Photoperiodic Induction of Reproductive Diapause in the Predator Geocoris uliginosus (Hemiptera: Geocoridae)," Annals of the Entomological Society of America 99(2), 300-304, (1 March 2006). https://doi.org/10.1603/0013-8746(2006)099[0300:PIORDI]2.0.CO;2
Received: 10 June 2005; Accepted: 1 October 2005; Published: 1 March 2006
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