Voltinism and Host Plant Use by Nezara viridula (L.) (Hemiptera: Pentatomidae) in Southeastern Queensland

Aspects of the ecology of Nezara viridula were studied in soybean‐growing areas of southeastern Queensland, Australia. Trends in population density, the number of generations, and the sequence of host plants used were investigated. Two principal generations were completed in a season, as shown by a bimodal occurrence of egg masses, nymphs and reproductively immature adult females. Nymphs were numerous relative to adults during two periods, once between late spring and early summer (mainly on wild crucifers: Rapistrum rugosum (L.) All. and Raphanus raphanistrum L.) and again in early autumn (on pod‐filling soybean). This pattern was consistent across study sites. Between midsummer and late summer, population densities were extremely low and most bugs were in the adult stage. the adult bugs were found on several host plant species, including Medicago sativa L., Datura ferox L., D. stromonium L., Ricinus communis L., Zea mays L., Sorghum bicolor (L.) Moench, Macroptilium lathyroides (L.) Urb. and Physalis virginiana L. Possible explanations for the low number of generations completed during the 8 months that the bugs were not in diapause and for low bug numbers during the summer months are evaluated. We suggest that host plant availability and suitability were the major factors contributing to the observed patterns in the population dynamics of N. viridula and that egg parasitism was not important.