A comparative study of postembryonic hematopoiesis in Spodoptera frugiperda and Pseudoplusia includens

Despite the fact that hemocytes play a critical role in cellular immunity, the production of hemocytes in postembryonic insects is a poorly understood process that may provide key insights into cellular immune function. That there are few definitive papers on the subject in the literature can be attributed to the fact that hemocytes of most insects are difficult to maintain in primary culture and few hemocyte specific molecular markers have been available until recently.; Research performed on the larval stages of Pseudoplusia includens , the soybean looper (Lepidoptera: Noctuidae), has shown that certain techniques can be used to reliably manipulate hemocytes of this insect in vitro (Strand and Noda, 1991; Pech at el. 1994). Many of the collection and culturing techniques are robust enough to be used for manipulation of hemocytes from other species of Lepidoptera. The ability to collect and maintain pure preparations of hemocytes has facilitated the production and characterization of P. includens anti-hemocyte monoclonal antibodies. With the aid of these monoclonal antibodies (mAbs), specific classes of hemocytes can be identified in P. includens (Strand and Johnson, 1996; Loret and Strand 1998, Gardiner and Strand 1999) and in a related noctuid species, Spodoptera frugiperda (fall armyworm). and Johnson, 1996; Loret and Strand 1998, Gardiner and Strand 1999) and in a related noctuid species, Spodoptera frugiperda (fall armyworm).; In this study, a comparison of postembryonic production of hemocytes was performed in larval P. includens and S. frugiperda . Characterization of anti-hemocyte mAbs was performed in conjunction with analyses of morphological characters and specific patterns of morphotype sedimentation on Percoll gradients. This multifaceted characterization permitted reliable immunological identification of specific hemocyte morphotypes in both noctuid larvae. Morphotype production was examined in vivo and in primary culture and morphotype analysis of proliferating hemocytes provided information on hemocyte lineage relationships in the two species. An examination of the hematopoictic response to immune challenge in both species provided some insight into the ability of hemocytes to recognize 'onself' and respond accordingly.