PHENOLOGY, DIAPAUSE, AND OVERWINTERING OF THE WHEAT BUG, NYSIUS-HUTTONI (HEMIPTERA, LYGAEIDAE), IN CANTERBURY, NEW-ZEALAND

At Lincoln, Canterbury, New Zealand, two generations of the wheat bug (Nysius huttoni) developed in annual weeds (Stellaria media, Coronopus didymus, and Polygonum aviculare) between October and February in 199 0-91 and 1991-92. Flight trapping indicated that a proportion of the p opulation emigrated from the weeds soon after adult emergence when new habitats, such as patches of fathen (Chenopodium album) and wheat (Tr iticum aestivum), were colonised. Gravid females comprised 47-80% of a ll females dissected during the first generation, but only 0-9.6% of s econd generation females. A small third generation, initiated by the l atter gravida, was detected in the field. Reproductive diapause, repor ted for the first time in the genus Nysius, was induced by transferrin g second generation female nymphs of the third and fourth instars, in late summer, to short day (12 h light: 12 h dark) conditions in the la boratory, where virtually no reproduction occurred over 80 days at 23. 5-degrees-C. Females transferred to long day (16 h light: 8 h dark) ph otoperiod, but otherwise identical conditions reproduced normally.