Microbiota and potential opportunistic pathogens associated with male and female fruit flies of Malaysian Bactrocera carambolae (Insecta: Tephritidae)

Abstract

Bactrocera carambolae Drew & Hancock is an agricultural pest that causes considerable damage to various fruit crops in Southeast Asia and South America. We report here the bacterial communities associated with field-caught male and female adult flies from University Malaya campus. The microbiota was determined by targeted 16S rRNA gene (V3–V4 region) sequencing using the Illumina MiSeq. At 97% similarity, four bacterial phyla (with relative abundance of ≥1% in at least one specimen) – Bacteroidetes, Firmicutes, Proteobacteria, and Tenericutes – were recovered from the adult flies. Proteobacteria was the predominant phylum in all the samples, with the female flies (86.81 ± 6.57%) having higher mean relative abundance than the male flies (71.57 ± 18.37%). The Firmicutes was more abundant in the male flies (14.47 ± 17.30%) than female flies (0.69 ± 1.25%). There were in total seven classes, nine orders, 13 families, 23 genera, and 31 putative species. Thirteen genera had higher mean relative abundance in male flies, and nine in female flies. Klebsiella was the predominant genus in female flies, while Desulfovibrio was more abundant in some male flies. The mean relative abundances of the putative species Orbus sasakiae and Enterococcus moraviensis were significantly higher in male than female flies, while female flies had significantly higher mean relative abundance for Escherichia fergusonii and Klebsiella variicola. Alpha diversity indices indicated that the bacterial diversity varied within and between male and female flies, and the mean bacterial diversity was significantly higher in male flies. The differences in bacterial diversity and relative abundance may be reasonably attributed to stochastic processes, in part to environmental factors such as food resources and habitats. It is significant that several putative bacterial species recovered in the present study have not been reported in Bactrocera fruit flies. Sixteen of the 31 detected putative bacterial species are potential opportunistic pathogens of medical/public health importance.