Avermectin Trunk Injections: A Promising Approach for Managing the Walnut Husk Fly (Rhagoletis completa)

Abstract

This study examined the larvicidal effect of trunk-injected abamectin and emamectin benzoate against the walnut husk fly (Rhagoletis completa Cresson, 1929). Walnut trees in two locations in two years were injected with the pesticides at different concentrations. For the toxicokinetic studies, the active ingredient content was measured in the leaves, flowers, husks, and kernels, using a UHPLC-MS/MS analytical method. The walnut husk fly infestation rates were between 3 and 70% and 10 and 34% for abamectin and emamectin benzoate, respectively, and were much lower compared to those measured for the control. The active ingredient content in the walnut husk showed a positive correlation with the larvicidal effect. The injections had a measurable but unsatisfactory insecticidal effect in the second year, when the economic threshold was exceeded. Trace amounts of the active ingredients were detected in the flowers. The residue analysis showed a declining concentration trend in the leaves over time. The largest quantities were detected in the leaves (≤439 ng/g of abamectin; ≤19,079 ng/g of emamectin benzoate), with concentrations in the husks of orders of magnitude lower (≤5.86 ng/g; ≤50.19 ng/g). The measurements showed no active ingredient residue above the MRLs in either fresh or dried kernels. The results indicate that trunk injections of abamectin, as well as trunk injections of emamectin benzoate, have the potential to suppress walnut husk fly populations.

The Advancement and Prospects of the Tree Trunk Injection Technique in the Prevention and Control of Diseases and Pests

“…In 2004, Calzarano's experiment proved that grapevines receiving trunk injection of Cyproconazole were in better nutritional condition and had higher yield and lower mortality rate than those without such injections, demonstrating the beneficial effect of fungicide injection through the trunk on root rot [41]. Injecting pesticides or antibiotics into a tree trunk has proven to be an efficient method for treating diverse tree diseases and preventing the invasion of harmful pests [6,[42][43][44][45]. In 2013, Akinsanmi's experiments showed that biannual application of phosphite during autumn and spring root wash periods effectively controlled tree decline in Australian macadamia trees [46].…”

An Evaluation of Insecticidal Trunk Injections for the Control of the European Cherry Fruit Fly Rhagoletis cerasi L. (Diptera: Tephritidae)

“…Endotherapy treatment is often used in urban plant protection for deciduous trees. Several experiments have demonstrated the successful use of trunk injection against different pests [21][22][23][24][25]. Walnut trees have been effectively treated with abamectin against the walnut husk fly (Rhagoletis completa) [24].…”

“…Several experiments have demonstrated the successful use of trunk injection against different pests [21][22][23][24][25]. Walnut trees have been effectively treated with abamectin against the walnut husk fly (Rhagoletis completa) [24]. The tiger longicorn beetle (Xylotrechus chinensis) is a pest to Mulberry (Morus sp.)…”