Fate of Acetamiprid and Imidacloprid aerially applied to the Pine Forest

Abstract

Fate of acetamiprid and imidacloprid aerially sprayed to control pine wood nematode (Bursaphelenchus xylophilus) were studied in a forest of Haman area. Acetamiprid 20% SL or imidacloprid 20% DC were diluted 100 times and applied two times as rate of 50 L/ha using an aircraft of Bell 206 L helicopter. Average acetamiprid deposits on forest floor ranged from 2 to 4% of standard aerial application rate. Following to the second application, acetamiprid deposits in the pine needle ranged 1.8~8.5 mg/kg and then gradually decreased to 1.2~2.1 mg/kg after 48 days. Deposits on the plant washed off by rainfall and reached to soil surface was ca. 17% of the application rate. All of acetamiprid on the ground resided in the forest floor covering the soil surface, where acetamiprid residues were decreased to a quarter at 48 days after the second application, but they were not detected in soil beneath it. And the only low level of acetamiprid residues, 0.0003 mg/L, was detected in the reservoir nearby the experimental forest on the day of aerial application. The acetamiprid detection was presumably due to spray drift. And average imidacloprid deposits on forest floor ranged from 1 to 3% of standard aerial application rate. Following to the second application, imidacloprid deposits in the pine needle analysed very low concentration of 0.1 mg/kg, but the amount of imidacloprid in wash-off in standard and two-fold treatment were ca. 8% and 4% of the application rate, respectively. Most of imidacloprid on the ground also resided in the forest floor, where imidacloprid residues were decreased to a twentieth at 111 days after the second application, and they were detected below 0.5% of the application rate in sol beneath it. And the low level of imidacloprid, 0.0003~0.0017 mg/L, were detected in the streams in the experimental forest. It was not to the level of contamination concerns.

Droplet deposition and pest control efficacy on pine trees from aerial application

“…Several studies have been carried out on the control of MAH by aerial application 20–22 . In China, aerial application of insecticides to MAH was adopted as early as 1984, but then the research stagnated for the next 30 years and only gradually re‐emerged in 2011 23 .…”

“…18,19 Several studies have been carried out on the control of MAH by aerial application. [20][21][22] In China, aerial application of insecticides to MAH was adopted as early as 1984, but then the research stagnated for the next 30 years and only gradually re-emerged in 2011. 23 A study by Yao et al 24 revealed that the aerial spraying of biocontrol bacteria as an alternative to the surface pathogenic bacteria of pine wood nematodes required a 48-h rain-free period.…”