On the Origins of Symbiotic Fungi in Carmine Cochineals and Their Function in the Digestion of Plant Polysaccharides.

Simple Summary: The domesticated carmine cochineal produces pigments used in food, cosmetics, and the textile industry. Its use dates to the pre-Hispanic period and thus is an Amerindian legacy. Cochineals grow and feed on the edible leaves of cacti. Since insects feed on plant sap, they may obtain their microbes from the plants and indeed we found here that some of the fungi in the insect guts are the same as those encountered in cacti. Fungi may help in digestion as they are capable of breaking down plant polymers in cultures and inside guts. We found fungi inside cochineals during microscopic examinations using different procedures to detect fungi. One of the isolated fungi produces a purple pigment that resembles the carminic acid. This study identified several potential functions of cochineal fungi and examined their plant origin. The cochineal insect Dactylopius coccus Costa (Hemiptera) has cultural and economic value because it produces carminic acid that is used commercially. In this study, distinct fungi were cultured from dissected tissue and identified as Penicillium, Coniochaeta, Arthrinium, Cladosporium, Microascus, Aspergillus, and Periconia. Fungi were microscopically observed inside cochineals in the gut, fat body, and ovaries. Since cochineals spend their lives attached to cactus leaves and use the sap as feed, they can obtain fungi from cacti plants. Indeed, we obtained Penicillium, Aspergillus, and Cladosporium fungi from cacti that were identical to those inside cochineals, supporting their plant origin. Fungi could be responsible for the degrading activities in the insect guts, since cellulase, pectinase, and amylase enzymatic activities in insect guts decreased in fungicide-treated cochineals. Our findings set the basis for the further study of the interactions between insects, fungi, and their host plants. [ABSTRACT FROM AUTHOR]