Ingestion of a marked bacterial pathogen of cotton conclusively demonstrates feeding by first instar southern green stink bug (Hemiptera: Pentatomidae).

Long-held dogma dictates that first instars of Nezara viridula (L.) do not feed, yet recent observations of stylet activity within a food source suggest otherwise. As a cosmopolitan pest of cotton and other high-value cash crops, confirmation of feeding by first instars may ultimately influence the knowledge on biology and management strategies for this pest. To determine whether first instars feed, newly hatched nymphs were provided sterile green beans (control) or beans infected with a rifampicin-resistant marked bacterial pathogen (Pantoea agglomerans (Ewing and Fife)) of cotton. Insects were exposed to beans for 2 d, and feeding was confirmed based on detection of marked bacteria ingested by the insect. Normal bacterial flora was detected in all insects; however, control insects did not possess the marked bacteria. Of the first instars surviving on infected beans, ≍65% possessed the marked bacteria internally. Furthermore, the frequency of insects with marked bacteria was higher in insects collected directly from the bean surface than those that were off the bean at time of collection. Densities of innate and marked bacteria were comparable (both ranging from 10(1) to 10(3)), suggesting that the marked bacteria did not exclude preexisting bacterial flora. Marked bacteria were also detected in a subset of second instars, indicating marked bacteria were retained through the molting process after ingesting bacteria as first instars. Our findings conclusively demonstrate feeding by first instars and redefine the long-held perspective of nonfeeding by first instars. These findings may necessitate changes to crop protection strategies against feeding and vectoring of plant pathogens by N. viridula.