Toxicity of an Emamectin Benzoate Microemulsion against Bursaphelenchus xylophilus and Its Effect on the Prevention of Pine Wilt Disease

Abstract

(1) Pine wilt disease (PWD) is a devastating disease of pine forests caused by the pine wood nematode (PWN), Bursaphelenchus xylophilus. Control of the disease is a worldwide problem due to the impossibility of using chemical nematicides on a large scale and for long periods. (2) Based on preliminary tests of microemulsion quality and stability, the optimum formulation was selected from 14 formulated microemulsions. The median lethal concentration (LC50) of the selected formulation at 48 h after treatment of B. xylophilus was 31.45 μg/mL of emamectin benzoate. The active ingredient reached the apical branches of Pinus thunbergii within 90 days of injection. (3) P. thunbergii was inoculated with B. xylophilus at 100 days post-injection, and the trees treated with the formulation remained uninfected for 450 days. Trunk injection exerted substantial control over PWD. (4) These results indicate that this formulation has the advantages of good transportability and long persistence in pine trees after injection and that it effectively prevents PWD. Therefore, this emamectin benzoate formulation can effectively reduce PWD occurrence in pine forests.

Sustainable DMSNs nano-biopesticide platform built by a “one-pot” method focusing on injury-free drug demonstration of pine wood nematodes

“…Nematodes that continuously swing or have bodies in an “S”, curly, wavy, or spiral shape are classified as live nematodes; nematodes that do not move have a “J” or “C” shaped body, or if the body is stiff, it is considered a dead nematode. 36 After centrifuging and shaking the eluting solution of pine wood nematodes, insect needles were used to detect nematodes under a microscope to avoid false death.…”

Effects of trunk injection with emamectin benzoate on arthropod diversity

“…The vegetation type is subtropical evergreen broad‐leaved forest. P. massoniana is the main component of the pine forest in Lin'an District, and Lin'an District is an epidemic area of PWD 30 . The research objects selected for this study include the following: forests of P. massoniana (26.67 hectares) after 1 year of trunk injection, forests of P. massoniana (26.67 hectares) after 2 years of trunk injection, forests of P. massoniana (26.67 hectares) after 3 years of trunk injection, and forests of P. massoniana without trunk injection, used as a control group.…”

“…Soil moisture content was measured by the drying method 77 . The residue of emamectin benzoate was measured by the HPLC method 30 . Organic soil matter was determined by the sulfuric acid potassium dichromate method 78 .…”

“…In one study, a microemulsion of 2% emamectin benzoate was used to control PWD, and the effect was significant; the duration could reach more than 3 years 29 . Also, emamectin benzoate‐soluble granules for trunk injection had a significant efficacy on PWD 30 . The application of trunk injection with emamectin benzoate has been widely promoted in the southeast provinces of China.…”

“…The pesticides can be delivered fully concentrated or diluted, and the product is then carried through the xylem and pulled up to the leaves by transpiration 31 . Emamectin benzoate is transmitted to the pine needles and flowers of P. massoniana via transpiration after trunk injection 30 . Emamectin benzoate residue in pine needles may affect the insects feeding on the needles, the residue in pine flowers may affect pollinators, and the residue in pine needle litter may affect the detritivores.…”