Spatial density and movement of the Lygus spp. parasitoid Peristenus relictus (Hymenoptera: Braconidae) in organic strawberries with alfalfa trap crops.
Alfalfa trap crops are currently used to manage Lygus spp. in organic strawberry fields on the California Central Coast. The retention of Lygus spp. in alfalfa creates aggregated distributions that provide improved opportunities for biological control by the introduced parasitoid Peristenus relictus (Ruthe). The abundance and distribution of P. relictus between two trap crops separated by 50 strawberry rows were analyzed in 2008 and 2010. Parasitism of Lygus spp. nymphs by P. relictus (measured by larval abundance and % parasitism) was greatest in alfalfa trap crops compared with strawberry rows. A significantly positive correlation between host nymphs and P. relictus larvae in and between trap crops was found. Movement of P. relictus adults from a marked alfalfa trap crop into adjacent strawberry rows or trap crops was also studied in 2008 and 2009 using a chicken egg-albumin enzyme-linked immunosorbent assay mark-capture technique. In 2008 and 2009, 85 and 49% of protein-marked wasps were captured from central trap crops, respectively, indicating that alfalfa trap crops act as a concentrated "host-density anchor" in organic strawberry fields.
Center for Agroecology and Sustainable Food Systems, University of California, 1156 High St., Santa Cruz, CA 95064, USA.
Sean L
SL
Swezey
Diego J
DJ
Nieto
Charles H
CH
Pickett
James R
JR
Hagler
Janet A
JA
Bryer
Scott A
SA
Machtley
D000704:Analysis of Variance; D063147:Animal Distribution / Q000502:physiology*; D000818:Animals; D002140:California; D031985:Fragaria / Q000469:parasitology*; D020062:Heteroptera / Q000469:parasitology*; D006790:Host-Parasite Interactions / Q000502:physiology*; D000455:Medicago sativa / Q000469:parasitology*; D009758:Nymph / Q000469:parasitology; D058871:Organic Agriculture / Q000379:methods*; D011156:Population Density; D014863:Wasps / Q000502:physiology*