Pain and Lethality Induced by Insect Stings: An Exploratory and Correlational Study

Abstract

Pain is a natural bioassay for detecting and quantifying biological activities of venoms. The painfulness of stings delivered by ants, wasps, and bees can be easily measured in the field or lab using the stinging insect pain scale that rates the pain intensity from 1 to 4, with 1 being minor pain, and 4 being extreme, debilitating, excruciating pain. The painfulness of stings of 96 species of stinging insects and the lethalities of the venoms of 90 species was determined and utilized for pinpointing future directions for investigating venoms having pharmaceutically active principles that could benefit humanity. The findings suggest several under- or unexplored insect venoms worthy of future investigations, including: those that have exceedingly painful venoms, yet with extremely low lethality-tarantula hawk wasps (Pepsis) and velvet ants (Mutillidae); those that have extremely lethal venoms, yet induce very little pain-the ants, Daceton and Tetraponera; and those that have venomous stings and are both painful and lethal-the ants Pogonomyrmex, Paraponera, Myrmecia, Neoponera, and the social wasps Synoeca, Agelaia, and Brachygastra. Taken together, and separately, sting pain and venom lethality point to promising directions for mining of pharmaceutically active components derived from insect venoms.

Keywords: Hymenoptera; ants; bees; envenomation; pain; peptides; pharmacology; toxins; venom; wasps.

Figure 1

Scatter diagram of sting pain level and lethality of all 71 species of Hymenoptera for which both values are available. The trendline is provided only for reference, as no significant trend was observed (r² = 0.013; P = 0.356).

Figure 2

Scatter diagrams of sting pain level and lethality showing potential trends among the taxa within the individual groupings of stinging Hymenoptera. (A) The 33 species of ants, (B) the 22 species of social wasps, (C) the 6 species of social bees, and (D) the 10 species of solitary bees and wasps. The ants exhibit the broadest range of values, while the values of the other groupings are more tightly clustered. The trendlines are provided only for reference, as no significant relationship between sting pain level and lethality was observed for any of the groups ((A) r² = 0.028. P = 0.354; (B) r² = 0.095, P = 0.162; (C) r² = 0.105, P = 0.532; (D) r² = 0.398, P = 0.0504).

Figure 3

(A) Sting apparatus of Pogonomyrmex badius showing sting shaft, tubular Dufour’s gland, and spherical venom reservoir with a long venom duct leading to the base of the sting shaft (scale bar = 1 mm). (B) Isolated venom reservoirs of Pogonomyrmex maricopa in a droplet of distilled water ready for the venom to be drained and the empty membranous reservoirs discarded (scale bar = 0.1 mm). Photos taken with an Olympus PM-10-A camera attached to an Olympus JM Zoom Stereo Microscope.