Submitted to: International Plant Protection Congress
Publication Type: Abstract Only
Publication Acceptance Date: 7/25/2007
Publication Date: 10/17/2007
Citation: Stanley, D.W., Tunaz, H. 2007. An immunological axis of biological control: microbial infections in field-caught insects [abstract]. International Plant Protection Congress. 2:436-437. Interpretive Summary:
Technical Abstract: We report on the hypothesis that insect immune effector systems limit the host range and effectiveness of microbial agents deployed for biological control. Formation of darkened, melantoic nodules is the predominant cellular immune reaction to microbial infection and once formed, the nodules are permanently attached to internal surfaces. The presence of melantoic nodules within the collected specimens can be taken as evidence of past microbial infections from which the specimens had recovered. To test our idea, we carried out a field study designed to assess the extent of natural microbial infections in insects collected from agrarian fields. Pest species were collected from fields surrounding Kahramanmara', Turkey. The specimens were identified and dissected under a microscope to assess numbers of nodules in the insect bodies. The collected insects were healthy as judged by behavioral observation, turgidity of larvae, and feeding activity. Of the >400 examined specimens, approximately 98% had been infected and recovered from the infection(s). Numbers of nodules ranged from ~2/individual to >100 nodules/individual. Most insects experience and recover from smaller or larger natural microbial infections in the field. The key implication of our finding future advances in the efficacy and use of biopesticides will depend on understanding and somehow attenuating insect innate immune effector systems. Some insect pathogens have already evolved effective mechanisms to achieve this advance.