Histrionicotoxin alkaloids finally detected in an ant

Area of Science:

• Chemical Ecology
• Zoology
• Entomology

Background:

• Ants can sequester alkaloids from their diet, influencing their chemical defenses.
• Poison frogs are known for their potent alkaloid toxins, primarily decahydroquinolines (DHQs) and histrionicotoxins (HTXs).
• Previous studies identified DHQs in ants but not HTXs, suggesting differing sequestration or biosynthetic pathways.

Purpose of the Study:

• To investigate the alkaloid composition of the ant Carebarella bicolor.
• To determine if histrionicotoxins (HTXs) are present in C. bicolor, alongside decahydroquinolines (DHQs).
• To compare the alkaloid profiles of C. bicolor with those of dendrobatid frogs.

Main Methods:

• Alkaloid extraction from ant specimens (Carebarella bicolor) and frog skin (Oophaga granulifera).
• High-resolution mass spectrometry to identify and characterize alkaloid structures and isomers.
• Comparative analysis of alkaloid profiles between ant and frog species.

Main Results:

• Carebarella bicolor ants contained major DHQs (269AB type) and minor DHQ isomers, similar to previous findings in other ants.
• For the first time in an ant species, six histrionicotoxins (HTXs) were detected, co-occurring with DHQs.
• New DHQ alkaloids of MW 271 and a trace DHQ of MW 273 were identified in the ants, with distinct isomers found in the comparison frog.

Conclusions:

• The co-occurrence of HTXs and DHQs in Carebarella bicolor represents a significant finding, mirroring the alkaloid profile of dendrobatid frogs.
• This discovery suggests a potential shared evolutionary or dietary source for these complex alkaloids in both ants and frogs.
• Further research is needed to elucidate the biosynthetic or sequestration mechanisms responsible for this unusual alkaloid combination in ants.