Euselasia chrysippe as a potential biocontrol for Miconia calvescens in Hawaiʻi Kenneth P. Puliafico,1* Jeselyn Calderón-Ayala,1,2 Nancy L. Chaney,1 Edward Bufil,1 M. Tracy Johnson1 1 Institute of Pacific Islands Forestry, PSW Research Station, USDA Forest Service, Volcano, Hawaii * [email protected] 2 KUPU-Hawaii: Hawaii Youth Conservation Corps / Americorps Programs Biology and Rearing Miconia Biocontrol Euselasia chrysippe (Lepidoptera: Riodinidae) is a small butterfly whose caterpillars Biological control is considered a feed on several Miconia species in its native Costa Rica. Larvae hatch from large egg critical tool for long term management masses (up to 115 eggs) (A), feed (B,C) and molt (D) in unison, moving between feeding of Miconia calvescens, a neotropical sites in single-file processions (E). This gregarious behavior is thought to improve feeding tree that is a major threat to Hawaiian on tough leaves, optimize foraging, and deter enemies. After 6 instars, larvae move off the forest ecosystems. Explorations in plant to pupate in smaller groups. Development from egg to adult is completed in about 2 Costa Rica and Brazil yielded several months, and adult females emerge one day prior to males from the same cohort (F). promising natural enemies which are Butterflies live up to 2 months along forest edges and gaps where Miconia calvescens A B being evaluated now for host occurs. C specificity. Our strategy is to develop Euselasia eggs from Costa Rica were hatched and larvae reared on Miconia plants in the a suite of biocontrol agents attacking G Hawai’i Volcanoes National Park Quarantine facility. Pupae were held in sleeve cages until stems, leaves and fruits of miconia. adult emergence. Sexed adults were released in a large walk-in cage (approx. 3x3x4m, G) Euselasia is our most promising leaf-feeding enemy of miconia, because with overhead mist irrigation and potted Miconia plants and shade cloth along one side to of its gregarious habit and potential to avoid the parasitoids that simulate the edge of a rainforest gap. Butterflies were offered nutrients in the form of commonly suppress other lepidopteran weed biocontrol agents in watermelon, banana, Néktar+ hummingbird food, wet clay soil from Mauna Kea, bird Hawaii. Results of our specificity testing indicate that E. chrysippe is droppings and canned tuna, which were refreshed every 2-3 days. suitable for introduction to our state. Mass rearing this species in Adults generally survived only 1-2 weeks – hand feeding with Néktar+ and mashed banana containment remains a significant challenge, in spite of our recent appeared to prolong survival. Although males were seen performing morning spiral mating breakthroughs. flights, copulation was not observed. Three sets of caged adults laid egg masses on the Future work with Euselasia chrysippe may involve exploring additional undersides of leaves of caged Miconia: in total 200+ eggs in May/14 (in a 2x2x2m cage), adult foods to improve butterfly survival, and limited testing of adults for 181 eggs in Dec/14, and 60+ eggs in Feb/15. Only 2 egg masses from Dec/14 appeared to D E F ovipositional specificity. be fertile, with 66 larvae hatching – the first successfully lab-reared Euselasia chrysippe. Host-specificity Methods: No-choice survival test Results (Figure 2) • 8 species of Melastomataceae from Hawaii. • Survival to pupation only on M. calvescens and Tetrazygia bicolor in Methods: No-choice feeding test • 10 first instars in 90mm Petri dishes or 13 first instars on whole plant experiments. • 73 plant species from Hawaii and Costa Rica potted plants (J), leaves replaced as necessary • No-choice survival to pupation restricted primarily to tribe Miconieae. • Whole or cut leaves in 90mm Petri dishes (H) • 3+ replicates per species, M. calvescens as controls (K). • One larva (out of 40) survived to pupate on Heterocentron • 4+ replicates per species, M. calvescens as control. • Observed every 2-4 days until pupation or larval mortality. subtriplinervium and needed 10 additional days to develop. • 10 early or 5 late instar larvae per dish exposed for 3 days • Number larvae surviving and time to pupation recorded. Miconieae Melastomeae 100% • Feeding assessed from 0 (no damage) to 5 (severe) (I) B B B B Petri dish 80% Results (Figure 1) Whole plant 60% • Varying levels of feeding on many Melastomataceae. A (No melastomes are native in Hawaii). H 40% 20% • M. calvescens and Tetrazygia bicolor most damaged of Damage ratings * ø C ø * * * * * ø melastomes occurring in Hawaii. 0% * • No sustained feeding outside Melastomataceae. Limited 0 1 2 3 4 5 “tasting” (damage rating 1) of some Myrtales. J K Figure 1, below. Euselasia chrysippe average feeding damage from no-choice tests conducted for 3 days in 90mm Acknowledgements: Thanks to Paul Hanson, Kenji Nishida and Pablo Allen (photos Figure 2. Survival to pupation for Euselasia chrysippe larvae Petri dishes. Replicate numbers along top axis. Plant species A, C-F) (Univ. of Costa Rica); J. A. González-Ramírez (OTS La Selva Biological on leaves in Petri dishes versus potted plants. Shared letters arranged phylogenetically. Miconia species in dark green are Station, Costa Rica). KUPU-Hawaii: Aunty Gina Carroll, Kim Matsukawa and HYCC not significantly different. Species arranged by tribe. Program Coordinator Malia Heimuli. Funding from USDA Forest Service, Hawaii Costa Rican hosts. * Native Hawaiian plants. I Invasive Species Council, and Hawaii Watershed Partnerships Program. (*) No pupation found. (ø) Not tested on potted plants. Order: Myrtales Tribe: Miconieae Family: Melastomataceae 5 5 5 10 5 9 6 2 4 9 5 2 229 2 5 4 14 8 5 6 4 6 9 6 6 4 4 11 10 9 12 4 13 8 3 4 5 6 4 4 4 3 4 8 4 6 10 4 6 6 4 4 3 7 5 4 5 6 4 6 4 4 4 4 4 9 5 4 4 7 4 5 4 5 5 4 4 3 3 2 2 Damage Damage Average Average 1 1 0 0.