Development of a Yeast Flora in the Adult Green June Beetle (Cotinis nitida, Scarabaeidae)

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Adult green June beetle guts contained no yeasts prior to the beetles' emergence from pupation. As beetles emerged from soil and fed, a gut yeast flora developed, increasing in size and changing in character with feeding duration from a largely fermentative flora to one in which obligately respiratory yeasts were prominent. Newly emerged adults after 24 hour feeding contained ca 103 colony-forming units of yeasts per milligram of gut; longer feeding on peach slices yielded ca 2 × 107 colony-forming units per milligram of gut. Aureobasidium pullulans, Candida guilliermondii, C. krusei, C. sake, C. tropicalis, Cryptococcus albidus var. albidus, Debaryomyces hansenii (3 biovars), Hanseniaspora uvarum, Hansenula californica, Rhodotorula glutinis, R. rubra, and Trichosporon cutaneum (2 biovars) were identified from gut and fecal samples. Peaches which had been fed upon acquired the major part of their yeast flora from the feeding beetles. Trichosporon cutaneum was positively selected in both beetle gut and peach slice environments; this species is predicted to be involved in production of semiochemical(s) responsible for beetle feeding aggregation enhancement.