1. 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

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

3. 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

4. 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

5. 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

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

7. 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

8. 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

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

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

11. 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 Ann. Entomol. Soc. Am. 99:

12. 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

13. 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 = ; 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)

14. 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)

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

16. 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

17. 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

18. 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

19. 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