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Title: Oviposition preference by Neomusotima conspurcatalis, a biological control agent for the invasive fern, Lygodium microphyllum

item Smith, Melissa
item Lake, Ellen
item Wheeler, Gregory

Submitted to: Entomologia Experimentalis et Applicata
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/26/2016
Publication Date: 7/7/2016
Citation: Smith, M.C., Lake, E.C., Wheeler, G.S. 2016. Oviposition preference by Neomusotima conspurcatalis, a biological control agent for the invasive fern, Lygodium microphyllum. Entomologia Experimentalis et Applicata. 160(1):11-17.

Interpretive Summary: Lygodium microphyllum continues to expand its range throughout south and central Florida. In 2008, after several years of testing and development, ARS scientists release Neomusotima conspurcatalis, a leaf-feeding moth. In 2013, during field surveys ARS scientists noticed that N. conspurcatalis seemed to be feeding primarily on fertile, spore-bearing fronds. Based on this observation, we conducted feeding and oviposition preference tests. While larvae displayed no preference for fertile fronds, we found that females deposited significantly more eggs on fertile fronds. We then conducted several analysis to determine a mechanism for the oviposition, but heretofore have not yet found a candidate compound to test. However, based on preference for the spore producing fronds, we may see more potential herbivore impact on the invasive plant when consumer populations are high and fertile fronds are present.

Technical Abstract: Lygodium microphyllum is a climbing fern that invades wildlands in central and south Florida, causing large habitat disturbance. Efforts to develop effective biological control strategia focused on crambid moths and a mite from the native range in Northeastern Australia. Neomusotima conspurcatalis is a foliage feeding moth that specializes on Lygodium species. Released in 2008, N. conspurcatalis has successfully established throughout much of the L. microphyllum invaded range in Florida. We investigated whether N. conspurcatalis display any preference (larval feeding or oviposition) between two different fern morphologies – fertile, spore producing fronds and sterile fronds. Furthermore, we examined whether oviposition on either fern type conferred any downstream advantages (e.g. weight, emergence success) to the offspring. Finally, we analyzed leaf Nitrogen and Carbon content and leaf volatiles to gauge differences between the frond types. We found that larvae, under choice and no-choice scenarios, consume approximately the same amount of leaf area and display no choice between fertile and sterile fronds. We observed a significant oviposition preference for fertile fronds over sterile fronds. Oviposition had no effect on larval development times, pupal weights or successful eclosure. Nitrogen and carbon content did not differ between fertile and sterile samples. However, we found significantly more 1-Octen-3-ol in sterile fronds, which may act as a repellent to ovipositing females. More research is needed to ascertain the precise mechanism, chemical or otherwise, behind ovipositon preference, but larval consumption of fertile fronds may confer better control of L. microphyllum in large populations during high sporulation periods.