Bacteria associated with carminic acid metabolism in the intestinal tract of three predators of Dactylopius opuntiae

Abstract

AbstractDactylopius spp. produce carminic acid as part of defence against predation. The average carminic acid concentration varies depending on the species, e.g., for prickly pear cochineal, Dactylopius opuntiae (Cockerell), and cochineal, Dactylopius coccus Costa (Hemiptera: Dactylopiidae), it is 3–5 and 19–25%, respectively. Generalist predators such as Laetilia coccidivora Comstock (Lepidoptera: Pyralidae) and specialist predators such as Leucopis bellula Williston (Diptera: Chamaemyiidae) and Hyperaspis trifurcata Schaeffer (Coleoptera: Coccinellidae) require detoxification mechanisms, which could be provided by gut bacteria. We determined the diversity of gut‐associated cultivable bacteria in these three predators and their ability to metabolize carminic acid. The bacteria were identified morphologically and by partial sequencing of the 16S rRNA gene. In vitro assays were done to determine their ability to metabolize carminic acid. The greatest culturable bacterial diversity was found in L. coccidivora larvae and H. trifurcata adults, followed by H. trifurcata larvae. The lowest diversity was found in L. bellula larvae. DNA sequencing revealed the presence of Bacillus cereus Frankland & Frankland, Enterococcus gallinarum (Bridge & Sneath) Collins et al., and Enterococcus casseliflavus Collins et al. in L. coccidivora larvae, Enterobacter spec. in larvae of H. trifurcata, Lactococcus lactis (Lister) Schleifer in adults of H. trifurcata, and Staphylococcus spec. in larvae and adults of H. trifurcata. Bacillus pumilus Meyer & Gottheil was only found in L. bellula larvae. In vitro assays showed that all isolates evaluated could metabolize carminic acid, suggesting they play an important role in the predators' ability to metabolize carminic acid. Presence of E. gallinarum, which had the most efficient metabolism of carminic acid, might allow L. coccidivora to feed on the two Dactylopius species regardless of carminic acid concentration.