Wasps possess venom, a biological substance deployed through their stinger. Understanding its nature and effects provides insight into their biology.
The Nature of Wasp Venom
Wasp venom is a complex mix of chemical compounds. It contains proteins (e.g., phospholipase A2, hyaluronidase), peptides (e.g., mastoparan, decoralin), enzymes, and biogenic amines (e.g., histamine, serotonin, acetylcholine). These contribute to its effects.
Venom is produced in glands within the wasp’s abdomen and stored in a venom sac. When stinging, a wasp uses its stinger, a modified egg-laying organ (ovipositor), to pierce the skin. It then pumps venom through the hollow stinger. Venom composition and potency differ among species, varying between social and solitary wasps.
Effects of Wasp Venom
Wasp venom triggers an immediate human response. Initial symptoms include sharp pain, burning, discoloration, swelling, and itching at the sting site. Neurotoxins stimulate pain receptors, while enzymes like phospholipases and hyaluronidases cause cell damage and inflammation, increasing blood flow and fluid leakage. The immune system recognizes the venom, initiating an inflammatory response that can also cause warmth.
Some individuals may experience systemic symptoms beyond localized reactions, even without a severe allergy. These can include nausea, headache, dizziness, fatigue, or a mild fever, particularly after multiple stings or a larger local reaction. The most severe reaction is anaphylaxis, a life-threatening allergic response. Anaphylaxis symptoms appear rapidly, often within minutes. These include severe swelling of the face, lips, or throat; hives or itching away from the sting; and breathing difficulties like wheezing or gasping.
Anaphylaxis can also cause a sudden drop in blood pressure, leading to dizziness, lightheadedness, and even loss of consciousness. Gastrointestinal symptoms like stomach cramps or diarrhea, and circulatory changes such as a weak or racing pulse, may also occur. Immediate medical attention and epinephrine administration are necessary for anaphylaxis.
Beyond the Sting: Venom’s Role in Wasp Life
Wasp venom serves purposes beyond its impact on humans, playing a role in the wasp’s ecological niche. A primary function is defense against predators or threats. Social wasps, living in colonies, use venom to protect nests and offspring from intruders. The painful sensation inflicted by the venom acts as a deterrent, discouraging larger animals from attacking.
For solitary wasp species, venom is primarily a hunting tool. These wasps use neurotoxic venom to paralyze prey (e.g., insects, spiders) without killing them. The immobilized prey remains alive, serving as food for developing larvae. This allows larvae to feed on a live host, providing a sustained food source. The ability to evolve venom composition provides wasps with an evolutionary advantage, allowing adaptation to new hosts and manipulation of metabolism, immunity, and behavior.