Mechanisms involved in the absorption of bioinsecticides and strategies to enhance their passage through the insect midgut

During the past decade a number of products have emerged from the effort to develop alternative biopesticidal technologies. The most recent approach to integrated pest management is based on the detection of new genes encoding for polypeptides with potential insecticidal activity, with a particular attention to biopesticides derived from viruses, microorganisms, fungi, plants and insects. Bacteria and viruses themselves can be used for biological control purpose. In most cases, biopesticides are molecules that have haemocoelic targets and must pass undegraded the gut barrier in order to exert their activity. Therefore for an effective oral delivery of these molecules it will be crucial to develop basic information on the molecular mechanisms mediating the absorption of proteins and peptides by the insect gut and to develop strategies to facilitate their passage through the midgut barrier. These issues have been the subject of my research project during these three years. In particular, I characterized the strategies adopted by Junonia coenia densovirus (JcDNV) to cross the midgut barrier of the lepidopteran pest Spodoptera frugiperda. I also studied a possible mechanism to increase the protein uptake in insect midgut characterizing the mechanisms involved in the internalization of selected Cell Penetrating Peptides (Tat, Penetratin, L-oligoarginine and D-oligoarginine) through the plasma membrane of lepidopteran larveae midgut cells. Even though these two aspects represent the main part of my PhD project, I have also collaborated to the study devoted to the identification of strategies to increase the permeability of the paracellular route.