Subterranean Acoustic Activity Patterns of Vitacea polistiformis (Lepidoptera: Sesiidae) in Relation to Abiotic and Biotic Factors.

Edidiong I Inyang,Violeta Tsolova,Raymond L Hix,Omotola Dosunmu,Richard W Mankin,Barukh B Rohde

doi:10.3390/insects10090267

Abstract

Grape root borer (GRB), Vitacea polistiformis, is a root-feeding pest of grapevines in the US southeast that causes underground damage well before vines show visible symptoms. A 269-d study was conducted at 31 sites in a Florida vineyard to record short bursts of insect movement and feeding vibrations in grapevine root systems and provide information that can improve timing and targeting of GRB management efforts. Characteristic spectral and temporal patterns in the subterranean vibrations facilitated discrimination of GRB from background noise and non-targeted arthropods. Infestation likelihood of GRB at each site was estimated from previous studies relating infestation to burst rate. In all, 39% of recordings indicated low infestation likelihood. Sites with medium or high infestation likelihood were confined to a small region of the vineyard where a vine with larval feeding damage was confirmed. The restricted area suggests that the biological control or chemical treatments could be reduced elsewhere. Acoustic activity was significantly greater in fall and winter than in spring, and greater in evening than afternoon; fall evenings seemed best for GRB acoustic surveys. The GRB seasonal and circadian acoustic variation reflected phenological variation in grape root growth and nutrients and was not significantly correlated with temperature.

Highlights

Vitacea polistiformis Harris (Lepidoptera: Sesiidae) larvae feed on grapevine roots in much of the southeastern US [1,2,3,4], reducing vineyard yields and increasing the susceptibility of vines to pathogens and drought [5]
No V. polistiformis were recovered from any of the five vine quadrant samples examined after the end of the study, but larval burrowing damage was observed in the root system of the vine completely excavated at the end of the fall season
Keeping in mind the uncertainties above, the results obtained from this study suggest, that future V. polistiformis management efforts may benefit from acoustic studies that focus on identification of aggregations of subterranean arthropod activity

Summary

Introduction

Vitacea polistiformis Harris (Lepidoptera: Sesiidae) larvae feed on grapevine roots in much of the southeastern US [1,2,3,4], reducing vineyard yields and increasing the susceptibility of vines to pathogens and drought [5]. Cultural practices that have been used for control of V. polistiformis include weed management to reduce survival of neonates attempting to burrow underground after dropping from eggs laid on or near grape foliage, mounding of soil beneath the vines after larvae have pupated, and covering of soil under vines with ground cloth to impede movement of newly emerged adults from subterranean cocoons to the ground surface [7]. None of these strategies are considered to be highly effective against V. polistiformis in Florida [2,4,10], partly due to difficulty in timing the peaks of neonate emergence as well as the period when larvae tunnel upwards from the root system to pupate near the surface. Maturing larvae may tunnel up into the mounded ridge before pupating if mounding has been done too early in the season [12]

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Conclusion