Physiological Consequences of Laboratory Rearing of Lygus hesperus (Hemiptera: Miridae)

Several aspects of the basic biology of the western tarnished plant bug, Lygus hesperus Knight, are poorly known despite the economic importance of this species. Among these are the factors regulating the adult diapause. Reports of recent studies questioned the validity of earlier reports of diapause in L. hesperus, in part because of the demonstrated loss of diapause response in insects obtained from long-standing laboratory colonies. However, use of laboratory reared insects would facilitate additional diapause research, so long as those insects exhibit a diapause response similar to that of the field population. L. hesperus, originating as eggs from field-collected insects, were reared in the laboratory for four generations to examine corresponding changes in selected biological characteristics. Over the course of the four generations, incidence of diapause in both L. hesperus genders decreased whereas the frequency of oviposition by virgin females increased. Measurable changes were not observed in frequency of occurrence of a specific fat body type (glass bead fat) or nymphal development time. These results suggest L. hesperus used in diapause research should be as close to the field population as possible, but no further removed than three generations. Results further demonstrate variability among different biological characteristics in their responses to selection from laboratory rearing. Collectively, these findings demonstrate the importance of understanding the influences of rearing on specific biological characteristics under study, and the need to verify the similarity of laboratory-reared insects to their native counterparts in studies used to draw inferences regarding the field population.