Seasonal Development of Plant Bugs (Heteroptera, Miridae): Subfamily Bryocorinae

Abstract

Data on seasonal development of plant bugs from subfamily Bryocorinae (Miridae) are reviewed and analyzed. All of the species of bryocorines whose seasonal development has been studied so far belong to the tribe Dicyphini, owing to the latter’s economic importance as agents of biological control in greenhouses. Macrolophus melanotoma, M. pygmaeus, and Nesidiocoris tenuis have homodynamic seasonal development and the lower developmental threshold of about 8–9°C. If food is available, they can remain active all year round and produce annually a varying number of generations, depending on the local climatic conditions. To survive adverse low-temperature winter conditions these species use various natural protected microhabitats and can overwinter at different developmental stages. The other two bryocorines studied (Dicyphus errans and D. hesperus) exhibit heterodynamic seasonal development and overwinter in the state of adult diapause. Induction of this diapause is controlled by a long day-type photoperiodic response. Also, the nymphal growth rate of D. errans is affected by day length and this quantitative photoperiodic response ensures that nymphs of this species reach the diapausing stage (adult) in appropriate time, which is crucial for successful overwintering. The threshold photoperiod for induction of winter adult diapause varies with latitude in D. hesperus, only nymphs being sensitive to day length in this species. Pilot experimental studies should precede any planned introduction of a biocontrol agent, as these may reduce the risk of invasions. During the early stages of settling in a new area, it is seasonal adaptations controlling development of bug populations in their natural environments that are particularly important. In greenhouses, higher efficiency of biocontrol measures can be achieved with southern multivoltine populations of homodynamic species, especially if these grow rapidly as immatures, have high reproduction rates at the adult stage, and easily switch to novel prey. Under field conditions, polyphagous heterodynamic univoltine species and populations with deep obligate diapause are more likely to naturalize successfully.