title: The effect of floral resources on parasitoid and host longevity: prospects for conservation biological control in strawberries.
abstract: The strawberry tortricid, Acleris comariana Lienig and Zeller (Lepidoptera: Tortricidae) is an important pest in Danish strawberry production. Its most common parasitoid is Copidosoma aretas (Walker) (Hymenoptera: Chalcidoidea: Encyrtidae). To identify selective flowering plants that could be used to increase functional biodiversity, the longevity of C. aretas and its host A. comariana was assessed on 5 flowering species: buckwheat, Fagopyrum esculentum Moench (Caryophyllales: Polygonaceae); borage, Borago officinalis L. (Boraginaceae); strawberry, Fragaria x ananassa Duchesne (Rosales: Rosaceae); phacelia, Phacelia tanacetifolia Bentham (Boraginaceae); and dill, Anethum graveolens L. (Apiales: Apiaceae). Dill was only tested with C. aretas. Sucrose and pollen served as positive controls, and pure water as a negative control. In a subsequent field experiment, A. comariana larval density was assessed at 1, 6, and 11 m distances from buckwheat flower strips in 3 fields. The proportion of field-collected larvae that were parasitized by C. aretas or fungi was assessed. Among the tested floral diets, buckwheat was superior for C. aretas, increasing its longevity by 1.4 times compared to water. Although buckwheat also increased longevity of A. comariana, its longevity and survival on buckwheat, borage, and strawberry was not significantly different, so buckwheat was chosen for field experiments. A. comariana densities in the 3 fields with sown buckwheat flower strips were 0.5, 4.0, and 8.3 larvae per m per row of strawberry respectively. Of the collected larvae, a total of 1%, 39%, and 65% were parasitized by C. aretas, respectively. The density of A. comariana and the proportion parasitized by C. aretas were highly significantly correlated. Distance from floral strips had no significant effect on either A. comariana larval density or on the proportion of individuals parasitized by C. aretas. Few other parasitoids emerged from collected larvae, and no larvae were infected by entomopathogenic fungi. Still, total A. comariana mortality was significantly affected by distance to flower strips, with the highest mortality near the flower strips. As no effect of buckwheat flower strips on C. aretas parasitism was found, the positive effect they had on A. comariana control stems from unknown mortality factors. As literature indicates that buckwheat for flower strips can augment a more complex suite of natural enemies, one such mortality factor could be a non-consumptive predator and/or parasitoid effect, but this requires further study. If confirmed, buckwheat may be utilized together with a selective food plant, once identified.
authors.affiliation: 1 University of Copenhagen, Department of Agriculture and Ecology, Zoology Group, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark.
authors.forename: Lene
authors.initials: L
authors.lastname: Sigsgaard
authors.forename: Cathrine
authors.initials: C
authors.lastname: Betzer
authors.forename: Cyril
authors.initials: C
authors.lastname: Naulin
authors.forename: Jørgen
authors.initials: J
authors.lastname: Eilenberg
authors.forename: Annie
authors.initials: A
authors.lastname: Enkegaard
authors.forename: Kristian
authors.initials: K
authors.lastname: Kristensen
mesh_terms: D028524:Anethum graveolens / Q000254:growth & development; D000818:Animals; D029683:Borago / Q000254:growth & development; D003718:Denmark; D019612:Fagopyrum / Q000254:growth & development; D005260:Female; D035264:Flowers / Q000254:growth & development; D020387:Food Chain; D031985:Fragaria / Q000254:growth & development; D005658:Fungi / Q000502:physiology; D029522:Hydrophyllaceae / Q000254:growth & development; D007814:Larva / Q000254:growth & development / Q000382:microbiology / Q000469:parasitology / Q000502:physiology; D008136:Longevity; D019684:Magnoliopsida / Q000254:growth & development*; D008297:Male; D009036:Moths / Q000254:growth & development / Q000382:microbiology / Q000469:parasitology* / Q000502:physiology*; D010063:Ovum / Q000254:growth & development / Q000469:parasitology / Q000502:physiology; D010572:Pest Control, Biological / Q000379:methods*; D011679:Pupa / Q000254:growth & development / Q000469:parasitology / Q000502:physiology; D014863:Wasps / Q000254:growth & development / Q000502:physiology*
references.citation: J Insect Sci. 2013;13:104
references.pmid: 24738921
references.citation: Ecology. 2011 Nov;92(11):2043-8
references.pmid: 22164828
references.citation: Ann Bot. 2008 Nov;102(5):675-84
references.pmid: 18765442
references.citation: Annu Rev Entomol. 2007;52:301-23
references.pmid: 16972766
references.citation: PLoS One. 2011 Apr 28;6(4):e19219
references.pmid: 21552530
references.citation: Biochem J. 1953 Jan;53(2):294-6
references.pmid: 13032068