Location: Invasive Plant Research LaboratoryTitle: Interactions between two biological control agents on Lygodium microphyllum
|JONES, IAN - University Of Toronto|
Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/20/2018
Publication Date: 12/2/2018
Citation: Jones, I., Lake, E.C. 2018. Interactions between two biological control agents on Lygodium microphyllum. Insects. 9(4):180. https://doi.org/10.3390/insects9040180.
Interpretive Summary: Lygodium microphyllum, Old World climbing fern, is an invasive weed in peninsular Florida. Two biological control agents are currently being reared and released to help control this fern: a leaf galling mite, Floracarus perrepae (Acariformes: Eriophyidae), and a moth, Neomusotima conspurcatalis (Lepidoptera: Crambidae). Because little is known about how these two species interact, we conducted a series of experiments to determine if the presence of galls created by the mite would change N. conspurcatalis oviposition behavior, development time, or survival, and if N. conspurcatalis caterpillars would directly consume mite galls. The moth laid more eggs on leaves that had been galled by the mite than ungalled leaves. Although N. conspurcatalis caterpillar development time did not differ between galled and ungalled leaves, survival was lower on galled material. Caterpillars consumed 13.5% of mite galls and consumption of galls increased over time as caterpillars had increasingly consumed the ungalled portions of leaves. Our results suggest that where the mite and moth co-occur in the field, competitive interactions could happen more frequently than previously anticipated. However, we do not expect these interactions to affect the establishment of either agent or the overall biological control program.
Technical Abstract: Lygodium microphyllum (Lygodiaceae) is an invasive climbing fern in peninsular Florida. Two classical biological control agents are currently being released against L. microphyllum: a leaf galling mite, Floracarus perrepae (Acariformes: Eriophyidae), and a moth, Neomusotima conspurcatalis (Lepidoptera: Crambidae). Little is known about how the two species interact in the field; thus, we conducted oviposition choice tests to determine the effects of F. perrepae presence on oviposition behavior in N. conspurcatalis. Further, we conducted feeding trials with N. conspurcatalis larvae to establish the effects of gall presence on larval survival and rate of development, and determine whether N. conspurcatalis larvae would directly consume F. perrepae galls. Neomusotima conspurcatalis laid significantly more eggs on mite galled (52.66 ± 6.211) versus ungalled (34.40 ± 5.587) L. microphyllum foliage. Feeding trials revealed higher mortality in N. conspurcatalis larvae raised on galled (60%) versus ungalled (36%) L. microphyllum material. In gall feeding trials, N. conspurcatalis larvae consumed or damaged 13.52% of galls, and the rate of direct gall feeding increased over time as leaf resources were depleted. Our results suggest that, where N. conspurcatalis and F. perrepae co-occur, competitive interactions could be more frequent than previously anticipated; however, we do not expect these antagonistic interactions to affect the establishment of either agent.