Olfactory responses of the multicoloured asian lady beetle (Harmonia axyridis) to vineyard volatiles

The introduced biological control agent 'Harmonia axyridis' (Coleoptera: Coccinellidae) has attained pest status in North America as its presence in vineyards during harvest may compromise the quality of the resulting wine. The objective of this thesis was to identify both attractants and repellents for 'H. axyridis', in order to manipulate beetle behaviour and presence in vineyards. The antennal response of 'H. axyridis' to grape ('Vitis vinifera' var. Riesling) volatile compounds was recorded by gas chromatographic-electroantennographic detection (GC-EAD). Compounds that consistently elicited antennal activity were hexanol, linalool, nonanal, and [beta]-caryophyllene. In a four-arm olfactometer, 'H. axyridis' were significantly attracted towards [beta]-caryophyllene but displayed no behavioural response to hexanol, linalool, nor nonanal. In a vineyard, sticky traps baited with antennally active compounds, alone and in combination, failed to attract beetles. In a four-arm olfactometer, ' H. axyridis' displayed a variable response to grapes during ripening, but there is some evidence that beetles prefer undamaged grapes over damaged grapes. The concentration of [beta]-caryophyllene was relatively constant throughout the ripening period and did not differ between damaged and undamaged grapes. In contrast concentrations of hexanol, linalool, and nonanal changed during berry ripening. The response of 'H. axyridis' to undamaged grapes suggests that beetles may be attracted to vineyards by olfactory cues; however, their response to antennally active grape compounds does not support this result. Sulphur dioxide, in the form of potassium metabisulfite (KMS), was determined to be an effective repellent against 'H. axyridis'. In a Y-tube olfactometer, 'H. axyridis' spent significantly less time in the KMS arm (2.5, 5, and 10 g/L) than in the control arm. When sprayed in a vineyard, KMS at 10 g/L consistently reduced the number of ' H. axyridis' on grape vines 24 h after application. Future research should establish the duration of KMS repellency and the effect of environmental conditions on repellency. Future studies should continue to examine the olfactory response of'H. axyridis' to grapes, as the composition of volatile compounds can vary greatly depending on the variety, environmental conditions, and cultural practices

Evaluation of compounds for repellency of the multicoloured Asian lady beetle (Coleoptera: Coccinellidae) in vineyards

AbstractThe multicoloured Asian lady beetle,Harmonia axyridis(Pallas) (Coleoptera: Coccinellidae), has become a pest in North American vineyards during harvest due to its adverse effects on wine quality. This study evaluated alternative products that may be suitable for use in vineyards as repellents to the beetle. Products were screened as repellent for multicoloured Asian lady beetle in short-term laboratory trials. Thirteen products significantly reduced the number of beetles on grapes,Vitis vinifera(Vitaceae). Products that showed a 50% or greater repellency were evaluated for residual repellency 24, 48, and 72 hours after application. In these trials, pine oil was highly repellent at each testing period, whereas the repellency of most other products decreased over time. Eight repellent compounds were evaluated in field trials in commercial vineyards that had high multicoloured Asian lady beetle populations. The number of beetles on vines was counted 2–6 and 24–28 hours after application. In the field, the most effective repellents overall were Biobenton and Buran, which reduced the number of multicoloured Asian lady beetles by 39 and 34%, respectively. The discovery of new repellents of multicoloured Asian lady beetle provides an opportunity to improve management of the pest in vineyards and to reduce risk of wine taint without using broad-spectrum insecticides.</jats:p