New insights into fungal diversity associated with Megaplatypus mutatus: gut mycobiota

Abstract

The ambrosial forest pest Megaplatypus mutatus causes high economic losses in Argentina and has been classified as an emerging pest in Europe. The high diversity of susceptible tree-species (native and non-native) and its wide geographical distribution turn this ambrosial beetle into a serious threat to forest plantations. This work aimed to characterise the fungal communities associated with M. mutatus` gut, compare the current results with previous culture-dependent and independent datasets and test the specificity of the fungal communities among adults, larvae and host-plants. A total of 2200 fungal strains were isolated by culture method from Males, Females and Larvae from Populus deltoides, grouping them into eleven fungal taxa. Additionally, the larval gut was studied by culture-independent method (454-pyrosequencing) analysing P. deltoides and Casuarina cunninghamiana. The Principal Component Analyses showed a separation between fungal species within adults and larvae, strongly suggesting that males and Graphium basitruncatum association would be even more specific than previously reported. The use of complementary culture-methods, integrated into different scales of study, reflected an important biological complexity in the studied interaction, showing that the specificity in the Fungi-M. mutatus association is given by key-fungal members such as Fusarium solani species complex, Candida insectalens, G. basitruncatum and Raffaelea spp. The multitrophic interactions between M. mutatus and gut-associated fungi were assessed for the first time. These results complement the data from culture methods previously reported, thus improving the accuracy and understanding of the fungal assemblages associated with M. mutatus.