Biology and management of Phytomyza gymnostoma: a new invasive pest of Allium crops in the eastern US Entomological Society of America – Eastern Branch March 19, 2018 Brian Nault1, Shelby, Fleischer3, Ethan Grundberg2, Teresa Rusinek2, Dana Roberts2 and Timothy Elkner4 1Cornell University 2Cornell Cooperative Extension 3Penn State University 4Penn State Cooperative Extension Photo: Andre Megroz Leafminer pests (Diptera: Agromyzidae) of Allium crops in U.S. American serpentine leafminer (Liriomyza trifolii) Vegetable leafminer (Liriomyza sativae) Leafminer pests (Diptera: Agromyzidae) of Allium crops in U.S. American serpentine leafminer (Liriomyza trifolii) Vegetable leafminer (Liriomyza sativae) *Allium leafminer (Phytomyza gymnostoma) *New invasive Allium pest in North America detected in 2015 Outline I. Origin and distribution II. Identification and phylogeny III. Host range and damage to Allium spp. IV. Biology and phenology V. Detection and management World distribution of P. gymnostoma CABI Crop Protection Compendium (2018) Origin – Poland (1858) 21 countries in Europe; 2 in Asia; 1 in North America North American distribution of Phytomyza gymnostoma First detected in Lancaster County, PA (2015) Confirmed in MD, PA, NJ and NY as of 3/14/18 Phytomyza gymnostoma (Loew) Allium leafminer Adult Photo: André Mégroz Photo: B. Nault Phytomyza gymnostoma (Loew) black body – 3.0 mm (2 to 3x larger than T. trifolli) large yellow frons white haltere Yellow tips on distal end of femurs Photo: E. Agallou and D. Collins Phytomyza gymnostoma (Loew) Female Male Photo: D. Roberts Photo: D. Roberts Solid black sternite Yellow “V” sternite Phytomyza gymnostoma (Loew) Adults feed on exudates from large oviposition marks; some eggs laid © The Author(s) 2018 Phytomyza gymnostoma (Loew) Larva (8 mm) Pupa 3-4 mm Photo: S. Spichiger Photo: T. Rusinek Photo: E. Grundberg Photo: R. Donoval Photo: R. Donoval Phylogeny of leaf- mining flies: (Diptera: Agromyzidae) Phytomyzinae splits with Agromyzinae Scheffer et al. (2007). Mol. Phylo. & Evol. 42(3): 756-775. Molecular phylogeny of Phytomyza * *P. gymnostoma is the only Phytomyza spp. that utilizes Alliaceae Winkler et al. (2009). Systematic Entomology. 34, 260–292 P. gymnostoma feeding damage detected on following Allium spp. Common name Allium species Damage documented Wild Onion Allium canadense Yes Nodding Onion Allium cernuum Yes Onion Allium cepa Yes Scallion Allium fistulosum Yes Giant Onion Allium gygantheum Yes Field garlic Allium oleraceum - Mediterranean Onion Allium paniculatum - Leek Allium porrum Yes Garlic Allium sativum Yes Chive Allium schoenoparasum Yes Round-headed leek Allium sphaerocephalon - Ramps Allium tricoccum - Garlic chives Allium tuberosum Yes Wild garlic Allium vineale Yes Barringer et al. 2018. J. of Integ. Pest Mang. 9(1): 8. Survey of P. gymnostoma detected in Allium crops in NY in 2017 Avg. no. Avg. no. Avg. no. % plants Farms % plants Crop marks/ larvae/ pupae/ w/ active (n) w/ marks plant plant plant mines onion 3 16 13 0 0 0.3 scallion 11 28 16 0.06 0 0.4 leek 13 20 21 1.04 1.0 4.9 chive 6 24 15 0 0 0.2 Damage by Phytomyza gymnostoma This type of damage does not occur with other leafminers Some onion and leek fields lost Larval mining and Twisting onion leaves bacterial rot in leek Photo: R. Donoval Photo: T. Rusinek Damage by Phytomyza gymnostoma Oviposition marks cause cosmetic injury to scallions and chives Photo: E. Grundberg © The Author(s) 2018 Biology of Phytomyza gymnostoma Adults live for up to two weeks; avg. 9 d in lab Ovipositon marks peak 3 d after eclosion Percentage of pupae to oviposition marks ~4% Larvae (4 instars) feed within leaves and move toward plant base to pupate or in surrounding soil One generation is completed in 73 days @ 20° C Two generations per year © The Author(s) 2018 Phenology of P. gymnostoma in U.S. Spring Generation Fall Generation Jan. Feb. March Apr. May June July Aug. Sept. Oct. Nov. Dec. Overwintering Summer OverwinteringOverwintering Pupae Pupae PupaePupae AdultsAdults AdultsAdults Eggs & larvae Eggs & larvaeEggs & larvae Adapted from Shelby Fleischer, Penn State Periods when Allium foliage is present Spring Generation Fall Generation Jan. Feb. March Apr. May June July Aug. Sept. Oct. Nov. Dec. Scallions and wild Allium spp. leek transplanted onion seeded onion Periods when Allium foliage is available for ovipositing Spring Generation Fall Generation Jan. Feb. March Apr. May June July Aug. Sept. Oct. Nov. Dec. Scallions and wild Allium spp. leek transplanted onion seeded onion Detection of P. gymnostoma Sticky cards are commonly used to monitor leafminer adult activity, but this has been largely ineffective for this P. gymnostoma Photo: B. Nault Photo: B. Nault Detection of P. gymnostoma Scout for oviposition marks on foliage Flies and marks on foliage often concentrated along field edges Photo: B. Nault Photo: B. Nault Photo: B. Nault Photo: B. Nault Management possibilities for P. gymnostoma on Allium crops Plant Resistance Chemical Control Cultural Control Biological Control Management possibilities for P. gymnostoma on Allium crops Plant Resistance Chemical Control None known Attract & kill? Insecticides Cultural Control Biological Control Row covers, delayed Parasitoids planting, crop rotation, trap cropping? Summary P. gymnostoma is expanding its range and/or better documentation of its presence Crops most vulnerable include scallions, leek and transplanted onion Monitoring approaches reliant on visual inspection Future Research Develop a degree-day model that can help predict emergence and longevity of populations Identify host plant preferences Describe infestation patterns in fields Monitor for parasitism Evaluate efficacy of conventional and OMRI-listed products applied via foliar and drip systems Identify how insecticides are managing this pest Acknowledgements Cornell University Molly Cappiello Riley Harding Souleymane Ouattara Grower Mark Rogowski S&SO Produce Funding NYS Ag and Markets Photo: Andre Megroz.