Journal of Insect Science: Vol. 10 | Article 31 Finlayson et al. Differential consumption of four aphid species by four lady beetle species Christy Finlaysona, Andrei Alyokhin, Serena Gross and Erin Porter The University of Maine School of Biology and Ecology, 5722 Deering Hall, Room 202, Orono, ME 04469-5722 Abstract The acceptability of four different aphid species Macrosiphum albifrons (Essig), Macrosiphum euphorbiae (Thomas), Macrosiphum pseudorosae Patch, and Myzus persicae (Sulzer) (Hemiptera: Aphididae), as prey for four lady beetle species, one native species Coccinella trifasciata L, and three non-native Coccinella septempunctata L, Harmonia axyridis Pallas, Propylea quatuordecimpunctata L (Coleoptera: Coccinellidae) were tested in the laboratory. The relative field abundance of adults of the same lady beetle species on host vegetation, Lupinus polyphyllus Lindley (Fabales: Fabaceae), Solanum tuberosum L (Solanales: Solanaceae), and Rosa multiflora Thunberg (Rosales: Rosaceae), both with and without aphids present was also observed. In the laboratory, H. axyridis generally consumed the most aphids, while P. quatuordecimpunctata consumed the fewest. The exception was P. quatuordecimpunctata, which consumed a greater number of M. albifrons nymphs, and C. trifasciata, which consumed a greater number of M. albifrons nymphs and adults, compared with the other two beetle species. Lady beetles consumed fewer M. albifrons compared with the other three aphid species, likely because of deterrent compounds sequestered by this species from its host plant. In the field, P. quatuordecimpunctata was the most abundant species found on L. polyphyllus and S. tuberosum. Keywords: predation, biological control, competition, non-native species Correspondence: a [email protected] Associate Editor: J.P. Michaud was editor of this paper. Received: 9 November 2008, Accepted: 9 January 2009 Copyright : This is an open access paper. We use the Creative Commons Attribution 3.0 license that permits unrestricted use, provided that the paper is properly attributed. ISSN: 1536-2442 | Vol. 10, Number 31 Cite this paper as: Finlayson C, Alyokhin A, Gross S, Porter E. 2010. Differential consumption of four aphid species by four lady beetle species. Journal of Insect Science 10:31 available online: insectsicence.org/10.31 Journal of Insect Science | www.insectscience.org 1 Journal of Insect Science: Vol. 10 | Article 31 Finlayson et al. Introduction or when prey is plentiful. Native lady beetle abundance, however, may be reduced through Lady beetles (Coleoptera: Coccinellidae) are competition with non-native species with known to be voracious predators of plant pests overlapping prey preferences. Additionally, such as aphids (Hemiptera: Aphididae) non-native lady beetles may alter aphid (Hodek 1973; Gordon 1985). It is often community structure. Determining differences assumed that aphidophagous lady beetles are in prey consumption by different lady beetle highly polyphagous, consuming most (if not species may provide insight into changes that all) aphid species that they encounter (Pedigo occur in systems where non-native species and Rice 2006). However, there is evidence become established. In the laboratory, one that not every aphid species is equally suitable native and three non-native lady beetle species for every lady beetle species (Obrycki and Orr were provided four different species of aphid 1990; Phoofolo and Obrycki 1997; Kalushkov prey and their consumption was recorded. To 1998; Michaud 2000; Kalushkov and Hodek determine if any differences documented in 2004; Mignault et al. 2006). For example, the laboratory were reflected in the field, lady Michaud (2000) conducted choice tests with beetle species were observed for their seven lady beetle species and two aphid association with these aphids under field species, Toxoptera citricida and Aphis conditions. spiraecola. Although all lady beetles tested consumed both aphid species, four species Materials and Methods Coccinella septempunctata, Coleomegilla maculata fuscilabris, Coelophora inaequalis, Study species and Olla v-nigrum, were not able to complete The four lady beetle species chosen for this their developmental cycle with either aphid study are aphidophagous (Gordon 1985) and species. Depending on the aphid species abundant in Maine in the same habitats consumed and the addition of supplements (Finlayson et al. 2008). The native lady beetle (pollen) to the diet, the other three species, species used was Coccinella trifasciata Hippodamia convergens, Cycloneda perplexa Mulsant, which is found from sanguinea, and Harmonia axyridis, varied Labrador south to New Jersey and west to considerably in the number of eggs laid, egg California and Alaska (Gordon 1985). The viability, larval development time, and adult non-native lady beetle species used were weight. Coccinella septempunctata L., Harmonia axyridis Pallas, and Propylea Lady beetles are commonly released to quatuordecimpunctata L. These three species combat a diverse range of pests (Gordon are Palearctic in origin and were intentionally 1985; Koch 2003), despite the fact that little is and inadvertently introduced in North known about specific prey preferences of America. C. septempunctata has been different species. The success of such pest established in North America since 1973 control measures depends, in part, upon the (Angalet and Jacques 1975), H. axyridis since willingness of the lady beetles to consume the 1988 (Chapin and Brou 1991; Tedders and pest in question. Releases of non-native Schaefer 1994), and P. quatuordecimpunctata species may supplement pest control by native since 1968 (Wheeler 1990). species when their prey species do not overlap Journal of Insect Science | www.insectscience.org 2 Journal of Insect Science: Vol. 10 | Article 31 Finlayson et al. Four aphid species that are abundant and for at least 20 generations on excised potato readily available in the region were chosen to foliage in the laboratory. Rose and lupine serve as the prey for the selected lady beetle aphids were collected in the field from host species. The potato aphid, Macrosiphum vegetation including multi-flora rose, Rosa euphorbiae (Thomas), feeds on over 200 plant multiflora Thunberg (Rosales: Rosaceae), and species (Blackman and Eastop 1984). The lupine, Lupinus polyphyllus Lindley (Fabales: green peach aphid, Myzus persicae (Sulzer), Fabaceae), respectively, and then maintained feeds on over 40 different plant families in the laboratory on excised host vegetation (Blackman and Eastop 1984). The hosts of the for up to 3 days before use in trials. rose aphid, Macrosiphum pseudorosae (Patch), include the genus Rosa and a variety For each experiment, 10 aphids of the same of herbaceous plants (Foottit and Maw 1997). species were placed, using a paintbrush, on an The lupine aphid, Macrosiphum albifrons excised leaflet held within a 100 x 15 mm Essig, is a specialist, feeding exclusively on polystyrene Petri dish. Leaves used in trials plants in the genus Lupinus (Blackman and were from the host plants from which aphids Eastop 1984). While M. persicae is believed were collected in the field, as previously to be Palearctic in origin (Blackman and stated. Each trial was initiated when a single Eastop 1984), the other three aphid species are lady beetle previously housed in a separate Nearctic (Stroyan 1981; Blackman and Eastop Petri dish was added to the Petri dish 1984). containing the aphids by quickly exchanging lids between the two Petri dishes when the Laboratory trials lady beetle was on the lid. After 24 hours, the Lady beetles were collected from the field 48- beetle was removed and the number of aphids 72 hours before test initiation, maintained on a remaining in the dish was recorded. When a 50/50 diet of honey/egg yolk, then provided partial aphid remained, it was estimated to the with water, but no food, for 48 hours before 0.25 aphid. The experiment was conducted test initiation. Lady beetles were collected separately with adult apterae and with first to from a variety of locations and plants in second instars. Sixty trials were conducted Orono, Maine (44.8835° N, 68.6721° W), that with each lady beetle species/aphid species included mixed shrub (Solidago sp., Rubus pairing: 30 replicates with adult aphids and sp., Prunus sp., Rosa sp., Cornus sericea, 30 replicates with the nymphs. Alnus sp.), apple (Malus sp.), grain (Hordeum sp., Avena sp.), mixed organic crops (Solanum Lady beetles, aphid colonies, and test dishes lycopersicon, Allium sp., Brassica sp., Pisum were housed in Percival I-33VL Intellus sp., Phaseolus sp.) and fallow fields (Phleum environmental chambers at a 16:8 L:D pratense, Trifolium sp., Cirsium sp., Vicia sp., photoperiod and 20! C. Trials with M. Fragaria sp.). euphorbiae and M. albifrons were conducted in 2005, from June 16 to August 12 and from Potato aphids and green peach aphids were June 2 to August 12, respectively. Trials with obtained from colonies maintained in the M. persicae and M. pseudorosae were laboratory. The colonies were originally conducted in 2006, from May 24 to August 16 founded by aphids collected from potato, and from August 10 to August 24, Solanum tuberosum (Solanales: Solanaceae), respectively. Trials were conducted in Presque Isle, Maine, and then maintained continuously throughout the range of dates Journal of Insect Science | www.insectscience.org 3 Journal of Insect Science: Vol. 10 | Article 31 Finlayson et al. and in random order with respect to beetle