second half of brown bag 3/12

Cytochrome P450 18A1 and Ectisteroid

• Cytochrome P450 18A1

  • Upregulated in both the brain and fat body of envenomated insects.

  • Responsible for degrading 20-hydroxyecdysone, the most active form of ectisteroids in insects.

  • Degradation prevents reaching the necessary concentration threshold for proper pupal development.

• Ectisteroid

  • Main insect hormone expressed during pupa development.

  • Essential for transformation from pupa to adult; without sufficient levels, development may halt.

  • Significance lies in its role in molting and metamorphosis in insect life cycles.

Tissue Specific Effects of Venom

• Imaginal Discs and Hormone Regulation

  • Hormones responsible for development of adult structures (legs, wings, antennae) in imaginal discs are downregulated in envenomated brains.

  • Imaginal discs: Specialized structures in pupa that develop into adult features, analogous to building blocks of limbs and wings.

  • Suppression of these hormones by venom affects normal adult development, preventing proper formation of structures.

• Cell Death in Imaginal Discs

  • Recent studies indicate that wasp venom targets imaginal discs for apoptosis (programmed cell death).

  • Apoptosis in these discs leads to a loss of hormone production and structural integrity.

  • Imaging studies show the presence of apoptosis markers, impacting developmental pathways.

Effects of Adipokinetic Hormone

• Adipokinetic Hormone

  • Upregulated in envenomated insect brains, involved in lipid mobilization and fat distribution throughout the body.

  • Generally activated during exercise but in the context of envenomation, it redistributes fat reserves, possibly to fuel energy for stress-response.

  • Changes in fat body structure observed, with envenomated insects displaying shredded fat tissues compared to intact control groups.

Cadherin 89D and Cell Adhesion

• Cadherin 89D

  • A cell surface protein crucial for cell adhesion, downregulated in envenomated fat bodies.

  • Loss of cadherins allows fat cells to disperse rather than remain clustered, resulting in increased free lipids in the hemolymph.

  • This breakdown of normal cell adhesion mechanisms could facilitate venomous effects by promoting increased mobility of fat cells and nutrients.

Role of Sarcotoxin II in Immune Response

• Sarcotoxin II

  • Upregulated in envenomated fat bodies, part of the insect immune system, typically acts as an antibacterial agent.

  • Its increase suggests potential protective measures against bacterial infections in larvae that may arise from feeding on decaying matter.

  • This adaptation might mitigate the risk of infection from the wasp's environment, where larvae emerge covered in bacteria and dirt.

Overview and Future Directions

• Research highlights the remarkable effects venom has on hormonal regulation and tissue structure in insects.

• Ongoing studies aim to understand the interplay between immune responses and the survival of wasp larvae amidst environmental challenges.

• Potential implications for broader ecological interactions and the evolutionary adaptive strategies of parasitic wasps.