Craig R. Roubos Entomology and Nematology Dept. University of Florida Parasitoids of Blueberry Gall Midge (Diptera: Cecidomyiidae) in Florida Blueberries and Potential for Biological Control Craig R. Roubos Entomology and Nematology Dept. University of Florida

Outline Blueberry Gall Midge Research Conclusions Biology Pest Status Natural Enemies Research Parasitoid Survey in Florida Blueberries Parasitism by Aprostocetus sp. Conclusions

Blueberry Gall Midge Biology Diptera: Cecidomyiidae Dasineura oxycoccana (Johnson) Native to eastern North America Feeds on species of Vaccinium Larvae feed in developing flower and leaf buds

Blueberry Gall Midge Pest Status In susceptible varieties, 80 – 90% of flower buds can be lost Insecticides are the only available management tools Malathion Spinosad Spinetoram Acetamiprid Rabbiteye Blueberry (Vaccinium virgatum Aiton) Flower Bud

Blueberry Gall Midge Natural Enemies Syrphidae Toxomerus marginatus (Say) and T. geminatus (Say) Ceraphronidae Aphanogmus sp. and Ceraphron palladiventris Ashmead Eulophidae Aprostocetus sp. Platygastridae Platygaster, Synopeas, Inostemma

Parasitoid Survey Objectives: Determine the parasitoid community composition at a Florida blueberry farm Determine seasonal dynamics of parasitoids during blueberry bud development

Parasitoid Survey Materials and Methods Yellow sticky traps (Pherocon® AM) placed in unsprayed rabbiteye blueberry bushes Traps collected weekly February – April 2009 Wasps removed from traps and identified

Parasitoid Survey: Results Family # specimens % of total Aphelinidae 106 4.4 Bethylidae 89 3.7 Braconidae 54 2.2 Ceraphronidae * 311 12.9 Encyrtidae 262 10.9 Eulophidae * 202 8.4 Eupelmidae * 129 5.4 Ichneumonidae 27 1.1 Mymaridae 96 4.0 Ormyridae 71 2.9 Platygastridae * 641 26.6 Pteromalidae * 154 6.4 Scelionidae 219 9.1 Trichogrammatidae 30 1.2 Collected 21 families of parasitic Hymenoptera Platygastridae was most commonly collected * family includes parasitoids of Cecidomyiidae

Parasitoid Survey: Results Seasonal pattern of trap catch for three families of interest (Gainesville, FL: yellow sticky traps 2009)

Parasitism by Aprostocetus sp. Objectives: Determine if Blueberry Gall Midge is parasitized by Aprostocetus sp. in Florida Determine parasitism rate

Parasitism by Aprostocetus sp. Hymenoptera: Eulophidae: Tetrastichinae Aprostocetus sp. collected in Mississippi (Sampson et al. 2006) Aprostocetus female Aprostocetus stinging through leaf bud Sampson, B.J., T.A. Reinhart, O.E. Liburd, S.J. Stringer, and J.M. Spiers. 2006. Ann. Entomol. Soc. Am. 99: 113-120.

Parasitism by Aprostocetus sp. Materials and Methods Midge larvae collected from infested leaf buds 18 March to 8 April 2009 Live larvae placed on microscope slides and parasitoid eggs counted in vivo Recorded host instar, host location (layer of leaf bud), and number of parasitoid eggs

Parasitism by Aprostocetus sp.: Results Host Instar n Mean % Parasitism (± SEM) Mean Eggs per Host 1 126 7.6 ± 4.2 a 0.04 ± 0.02 a 2 272 44.0 ± 5.0 b 0.64 ± 0.06 b 3 125 62.9 ± 5.3 c 1.19 ± 0.11 c χ2 = 111.03; df =2; P < 0.001 F = 45.3; df = 2, 514; P < 0.001 Total parasitism: 37.3% (n=523) Superparasitism observed in 43% of parasitized larvae Means followed by the same letter are not significantly different (P > 0.05)

Parasitism by Aprostocetus sp.: Results Leaf Layer Mean % Parasitism (± SEM) Outer 52.0 ± 4.6 a Middle 39.8 ± 5.1 b Inner 22.6 ± 6.3 b χ2 = 25.3; df =2; P < 0.001 Means followed by the same letter are not significantly different (P > 0.05)

Conclusions Diverse parasitoid fauna in Florida blueberries Including Platygastridae, Ceraphronidae, and Eulophidae Platygastrids were the most frequently collected 26.6% of total

Conclusions Aprostocetus sp. (Eulophidae) was the dominant parasitoid during leaf bud development Total parasitism 37.3% Parasitism by Aprostocetus sp. was highest in third instar host larvae and in the outer layer of leaf buds

Future Research Expand the parasitoid survey Collect from all blueberry growing regions in Florida Conventional management in addition to organic Study parasitism by Platygastridae Compare Florida and Mississippi Aprostocetus species Study parasitoid biology Functional and numerical response

Potential for Biological Control? Conservation biological control should be practiced to prevent the disruption of naturally occurring parasitoid communities Careful timing of insecticide applications Reduced-risk insecticides

Acknowledgements Small Fruit and Vegetable IPM Laboratory Dr. Elke Weibelzahl Teresia Nyoike Julia Joy Gainey Florida Blueberry Growers Association FES Student Activities Committee minigrant Dr. Oscar E. Liburd Dr. Robert McSorley Dr. Paul Lyrene Dr. Dakshina Seal Dr. Blair Sampson Gainesville Organic Blueberry Farm