Aphid Numbers Crashing in Mississippi Wheat Fields

Over the last 5-7 days aphid numbers have started crashing in wheat fields around the state.  Our wheat test in Starkville went from several hundred per row foot on April 1st to less than 10 on April 4.  Many consultants and dealers have told me they are seeing the same thing.  A lot of this can be attributed to parasitized aphids from Lysiphlebus testaceipes (small parasitic wasp) but other cases may be contributed to various diseases that will take out aphid populations.  At this time, I would not recommend further aphid treatments, unless an extreme circumstance exists.  There were obvious differences in spring aphid populations this year where insecticide seed treatments were used compared to where they were not.  Wheat treated with insecticide seed treatments on average did not reach the outbreak levels compared to untreated fields.  This is because in Mississippi most aphid populations that are colonizing wheat come in the fall and when conditions warm up in the spring populations increase rapidly.  Insecticide seed treatments are doing a decent job controlling those aphids in the fall that would eventually increase to large numbers in the spring.  We will report our yield results from seed treatment test and foliar aphid sprays when they become available.

Parasitized Aphids by Lysiphlebus Photo by R. Leonard