Scrutinizing biological control survey data from the native range – the phylogeny and Lygodium fern host associations of Musotiminae moths

Authors: MCCULLOCH, GRAHAM - University Of Otago; MAKINSON, JEFFREY - Australian Biological Control Laboratory, ARS; ZONNEVELD, RYAN - Australian Biological Control Laboratory, ARS; PURCELL, MATTHEW - Australian Biological Control Laboratory, ARS; BROOKES, DEAN - University Of Queensland; GURDASANI, KOMAL - University Of Queensland; Lake, Ellen; RAGHU, SATHYAMURTHY - Australian Biological Control Laboratory, ARS; WALTER, GIMME - University Of Queensland

Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/12/2019
Publication Date: 7/1/2019
Citation: McCulloch, G., Makinson, J., Zonneveld, R., Purcell, M., Brookes, D., Gurdasani, K., Lake, E.C., Raghu, S., Walter, G. 2019. Scrutinizing biological control survey data from the native range – the phylogeny and Lygodium fern host associations of Musotiminae moths. Biological Control. 134:123-129. https://doi.org/10.1016/j.biocontrol.2019.04.004.
DOI: https://doi.org/10.1016/j.biocontrol.2019.04.004

Interpretive Summary: Lygodium microphyllum, Old World climbing fern, is one of the most damaging environmental weeds in Florida. Despite substantial efforts to control this fern, it continues to spread rapidly through the Greater Everglades ecosystem and other regions of Florida. Biological control is considered a critical component of the management strategy to control this weed. Foreign exploration for natural enemies that could serve as biological control agents is ongoing. Several moths in the family Crambidae, subfamily Musotiminae have potential to be biological control agents because they are relatively abundant on Lygodium and appear to be host-specific. We amplified three genes (COI, 18S rRNA and 28S rRNA) from these moths to assess the phylogenetic relationships among these moths and their host-specificity, relative to the locations where they were collected. This also enabled evaluation of the evolutionary history of their different larval feeding modes. Stem boring and leaf feeding species were separated into well-supported monophyletic clades. No obvious signals of unrecognised host-specific cryptic species were detected, though further investigation is required. Our results emphasize the value of complementing initial field surveys with molecular screening. This approach provides valuable information on the biogeographic distribution, genetic structuring, and likely host-specificity of potential biological control agents. It also provides a basis from which to direct additional sampling, identify targets for further foreign exploration, and set up hypotheses about the ecology, species status and evolutionary history of the organisms for further tests.

Technical Abstract: Lygodium microphyllum is considered one of the most damaging environmental weeds in Florida. Despite substantial efforts to control this fern, it continues to spread rapidly through the Greater Everglades ecosystem and other regions of Florida. Biological control is considered a critical component of the management strategy to control this weed, and foreign exploration for natural enemies is ongoing. A number of crambid moths from the subfamily Musotiminae are considered the most promising of the potential biological control agents found to date, because they are relatively abundant on Lygodium and apparently host-specific. We amplified three genes (COI, 18S rRNA and 28S rRNA) to assess the phylogenetic relationships among these moths and their host-specificity (all in relation to geography). We could thus also examine the evolutionary history of their different larval feeding modes. Stem boring and leaf feeding species were separated into well-supported monophyletic clades, implying these distinct feeding strategies are not labile. Limited genetic structuring was typical within each moth species, and no obvious signals of unrecognised host-specific cryptic species were detected, though further investigation is required, particularly for Eugauria albidentata. Our results emphasize the value of complementing initial field surveys with molecular screening. Such an approach provides valuable information on the biogeographic distribution, genetic structuring, and likely host-specificity of potential biological control agents. Less widely appreciated is its provision of a basis from which to direct additional sampling, identify targets for further foreign exploration, and set up hypotheses about the ecology, species status and evolutionary history of the organisms for further tests.