Entomopathogenic nematodes are effective at killing plum curculio larvae in the soil

Authors: PINERO, JAIME - University Of Massachusetts; Leskey, Tracy; Shapiro Ilan, David

Submitted to: Fruit Notes
Publication Type: Trade Journal
Publication Acceptance Date: 12/14/2018
Publication Date: 1/3/2019
Citation: Pinero, J.C., Leskey, T.C., Shapiro Ilan, D.I. 2019. Entomopathogenic nematodes are effective at killing plum curculio larvae in the soil. Fruit Notes. 84(Winter): 9-11.

Interpretive Summary: Plum curculio is a major pest of stone fruits (peaches, plums, cherries) and pome fruits (apples, pears). The adult insect attacks the fruit on the tree; larvae then develop in the soil becoming pupae, and then the insect emerges as an adult to start the cycle over again. Due to environmental and regulatory concerns, alternatives to broad spectrum chemical insecticides are needed to control this pest. A multi-stage (below and aboveground) strategy is being developed to kill the pest. Attractive lures cause the insects to congregate in the canopy of “trap trees” which are then sprayed with pesticides (but the amount of chemical pesticides used in this approach is reduced by 90%). Some plum curculio will survive the trap tree applications, so we then also apply entomopathogenic nematodes to the ground-dwelling stages to kill off the remaining pests. Entomopathogenic nematodes, also called beneficial nematodes, are small round worms that are used as environmentally friendly bio-insecticides. These beneficial nematodes (especially a species called Steinernema riobrave) are highly effective at killing below-ground stages of plum curculio. The multi-stage integrated approach represents a sustainable and environmentally friendly approach to controlling plum curculio; the approach may be adopted for control of other important insect pests as well.

Technical Abstract: We discovered that the entomopathogenic nematode, Steinernema riobrave, is effective at killing plum curculio, Conotrachelus nenuphar, larvae in the soil. The overall goal of this research is to use entomopathogenic nematodes as a biocontrol component of an IPM program targeting multiple stages of plum curculio. The approach utilizes attractive lures to pull adult plum curculio to selected perimeter-row trees. The canopies of these “trap trees” are then sprayed with adult-killing insecticides while the other trees in the block do not receive above-ground insecticides to control the pest. By only spraying odor-baited trees the total number of trees that receive insecticide treatment can be reduced by more than 90%. Consequently, adult plum curculio aggregate in the canopy of trap tree and there is also aggregation of fruit injury. As shown in our study and also from previous research, entomopathogenic nematodes can then be applied to the soil of those trap trees to kill plum curculio larvae, which will also be concentrated in those areas compared to any other trees in the orchard.