Reproductive behavior of Urostylis annulicornis Scott (Heteroptera, Urostylididae) in the southern Far East of Russia

The reproductive behavior of the oak bug Urostylis annulicornis Scott, 1874 was studied for the first time. This species lives in the crown of tall Quercus mongolica Fisch. ex Ledeb. trees making it difficult to access for study and observation. Our study aimed to elucidate the timing of mating and oviposition of U. annulicornis and the effect of temperature variations on the lifespan of adults in natural conditions. Nymphs grown from eggs that had overwintered on rhytidome fragments were placed in stationary netting cages installed on oak saplings, where the bugs were kept until adulthood. The behavior of the control pairs was monitored for 15 hours a day (from 06:00 to 21:00). The duration of an uninterrupted tandem during copulation was confirmed by additional observations at night. To facilitate egg-laying, artificial shelters were created from pieces of oak bark stacked together, attached to the stem of the plant, and placed inside cages. The number of eggs laid by the female was counted and photographed. The process of oviposition by a female on the oak tree bark in natural conditions was recorded and documented for the first time. This study of the biology of U. annulicornis, from oviposition through the sequence of postembryonic development, documenting all stages of metamorphosis, was carried out on a single plant. A summer reproductive diapause was observed in the seasonal cycle of the species. The timing of mating in U. annulicornis was shifted to autumn, the laying of overwintering eggs occurred in October, as night temperatures decreased. Males were observed performing postcopulatory mate-guarding. The effect of night cold spells on the lifespan of bugs was recorded: natural mortality of adults occurred when the night temperatures dropped below zero.