Insects Associated with Cover Crops in Massachusetts

Insect faunae were evaluated for ten cover crops grown in two replicated trials. Five crops were assessed in the principal experiment: (1)Faba bean, Vicia faba L. cv ‘Ipro’ (Fabaceae); (2) Hairy vetch, Vicia villosa Roth (Poaceae), planted in mixture with rye, Secale cereale L. cv ‘Aroostook’ (Poaceae); (3) Annual white sweetclover, Melilotus alba Desrousseaux var. annua Coe cv ‘Hubam’ (Fabaceae); (4) Grain sorghum, Sorghum bicolor (L.) Moench cv RS-610 (TE-66) (Poaceae); and (5) Buckwheat, Fagopyrum esculentum Moench (Polygonaceae). An ancillary experiment concerned an additional 5 crops: (1)‘Austrian Winter’ field pea, Pisum sativum L. var arvense(L.) Poiret (Fabaceae) interseeded with rye; (2) Canadian field pea, P. sativum var. arvense, interseeded with rye; (3)Cowpea, Vigna unguiculata(L.) Walpers ssp. unguiculata cv ‘Mississippi Silver’ (Fabaceae); (4)Maximilian sunflower, Helianthus maximiliani Schräder cv ‘Aztec’ (Asteraceae); and (5)Canola, Brassica napus L. (Brassicaceae).Shake samples and whole-plot visual inspections indicated, respectively, that faba bean sustained relatively high densities of bean aphid, Aphis fabae Scopoli (Homoptera: Aphididae), and associated lady beetles (Coleoptera: Coccinellidae) during late June. By contrast, sorghum featured high densities of corn leaf aphid, Rhopatosiphum maidis (Fitch), and lady beetles during the first three weeks of July. Hairy vetch/rye harbored particularly high densities of aphids (pea aphid, Acyrthosiphon pisum [Harris], on hairy vetch; corn leaf aphid and English grain aphid, Sitobion avenae [Fabricius], on rye) on July 8th and 23rd, and exhibited consistently-high densities of aphids and aphidophaga, including adult Syrphidae (Diptera). Sweetclover aphid, Therioaphis riehmi (Börner), was at times abundant on annual white sweetclover, but did not attract many aphidophaga. Shake samples showed that hairy vetch and buckwheat harbored relatively-high densities of insidious flower bug, Orius insidiosus (Say) (Hemiptera: Anthocoridae), and tarnished plant bug, Lygus lineolaris (Palisot de Beauvois) (Hemiptera: Miridae). Shake sampling also indicated relatively-high densities of saccharophilous ants on faba bean and on buckwheat. Whole-plot inspection showed that relatively-high densities of nectarivorous predatory wasps (Hymenoptera: Vespidae and Sphecidae) were attracted to the flowers of buckwheat (18 taxa of wasps observed) and annual white sweetclover (11 taxa).At various times during July and early August, ‘Austrian Winter’ pea/rye and Canadian field pea/rye harbored relatively-high densities of aphids (pea aphid, corn leaf aphid, and English grain aphid, pooled). Whole-plot visual inspection showed that ‘Austrian Winter’ pea/rye exhibited the highest densities of aphidophaga on July 8th and 11th.Several of the crops tested in the principal study may prove useful both as cover crops and field insectaries on truck farms in New England. However, cultural practices may require adjustment to permit reproduction and survival of beneficial insects.