Effect of the Localized Insecticides Spray Technique to Control Halyomorpha halys in Actinidia chinensis Orchards

Abstract

Kiwifruit (Actinidia chinensis) cultivation is expanding worldwide, with China, New Zealand, and Italy being the major producing countries. Halyomorpha halys, the brown marmorated stink bug, is raising serious concerns to kiwifruit cultivation both in China and Italy. This study aimed at improving the chemical control efficacy against this pest by comparing two insecticide spray techniques (a conventional ray atomizer and a trumpet-modified atomizer adapted for localized spray application) in kiwifruit. In fact, kiwifruit is often grown with a 'pergola' training system, which may reduce the effectiveness of insecticide penetration into the canopy. Experiments were performed in naturally infested orchards of both Actinidia chinensis var. chinensis 'Jintao' and A. chinensis var. deliciosa 'Hayward'. Furthermore, mesh cages containing H. halys adults were deployed within orchards to assess the insects' mortality at 1, 3, 7, and 10 days after an insecticide application with two spray techniques during two consecutive seasons. In the cultivar 'Jintao', the two systems performed similarly, while in the cultivar 'Hayward', an overall significantly higher insect mortality was recorded with the trumpet atomizer (94-100%) compared to the conventional atomizer (59-78%). Crop damage was also evaluated on both cultivars, simulating the grower insecticide applications with the two spray techniques. At harvest, no difference emerged between the spray techniques, which provided a significantly better protection compared to the untreated control (12-17% compared to 33-47% of injured fruits). Further investigations in this direction are needed also considering the restriction of insecticidal active substances ongoing in the European Union and the need to maximize the efficacy of the available tools.

Keywords: atomizer; brown marmorated stink bug; chemical control; fruit damage; insecticide application; integrated pest management; kiwifruit.

Figure 1

(A) Conventional ray atomizer commonly used by kiwifruit growers in Italy. (B,C) Detail of the nozzles installed radially around the fan. (D) Trumpets-modified atomizer used to localize the insecticides distribution in the fruit area. (E) Detail of the ‘trumpets’ installed in the localized spray technique and used in this study to apply insecticides against Halyomorpha halys in the kiwifruit orchard delivering the products in the fruit area.

Figure 2

Schematic representation of kiwifruit vine training system ‘pergola’ for Actinidia chinensis var. chinensis ‘Jintao’ (A,B) and A. chinensis var. deliciosa ‘Hayward’ (C,D) with the conventional ray atomizer and the trumpets-modified atomizer, respectively.

Figure 3

Kiwifruit with internal corking due to Halyomorpha halys trophic activity; each white spot corresponds to a H. halys feeding puncture. (A). Damage on Actinidia chinensis var. chinensis kiwifruit cultivar ‘Jintao’. (B). Damage on A. chinensis var. deliciosa cultivar ‘Hayward’.

Figure 4

Trend of Halyomorpha halys catches during season 2021 in the Dead-Inn^® pyramid monitoring trap (AgBio Inc. Westminster, CO, USA) baited with Pherocon^® BMSB lure (Trécé Inc. Adair, OK, USA). The kiwifruit phenology between blooming (crop BBCH 65) and harvest (crop BBCH 85) is reported for cultivars ‘Jintao’ (in yellow) and ‘Hayward’ (in green) together with the insecticide applications carried out in 2021.

Figure 5

Effects of treatments and kiwifruit cultivars on the mean number of H. halys feeding punctures per fruit. Different letters indicate a significant difference among the treatments as detected by the Tukey HSD test (p < 0.05), and the asterisk indicates a significant main effect of the kiwifruit cultivars.