Vegetable Crops News

Wild Cabbage Relatives In the Field Improves Diamondback Moth Control

What effects do wild and cultivated Brassicaceae host plants have on diamondback moth and parasitism by the wasp Diadegma insulare? Results of recent research show that the diamondback moths lay more eggs on the Brassica crops, especially broccoli, and the fewest on wild Brassicaceae, especially hoary alyssum (Berteroa incana) and wormseed mustard (Erysimum cheiranthoides). Egg hatch is not significantly different among host plants.

Diamondback moth larvae generally survive better on the Brassica crops, including cabbage and broccoli, than on wild Brassicas, and not at all on yellow rocket (Barbarea vulgaris). It also takes longer to complete their development on the wild Brassicaceae than on the Brassica crops.

D. insulare parasitized the fewest diamondback moths on hoary alyssum, field pepperweed (Lepidium campestre) and wormweed mustard. More diamondback moth larvae were parasitized on wild mustard (B. kaber) than on the other wild Brassicaceae. Also, parasitized larvae fed on wormseed mustard, field pennycress (Thlaspi arvense), and hoary alyssum took significantly longer to develop to D. insulare pupae than when they were fed on the other Brassicaceae plants.

Diamondback moth infestation and percentage of parasitism in the field were higher on broccoli than on the other Brassica crops. The presence of wild Brassicaceae, especially yellow rocket and wild mustard, in the field could reduce diamondback moth populations, increase the impact of D. insulare, provide a reservoir for insecticide-susceptible diamondback moth, and increase the success of diamondback moth management programs.

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