Insecticides used to manage spotted lanternflies in nurseries, 2023

Maple | Acer spp

Spotted lanternfly | Lycorma delicatula

cyantraniliprole, flupyradifurone, dinotefuran, Metarhizium brunneum

Field tests were conducted to evaluate the efficacy of various insecticides against the spotted lanternfly (SLF). Adults were collected from infested Ailanthus trees in Cockeysville, Maryland and transported to Manor View Farm (Monkton, MD) on 30 August 2023. The insecticides tested were Safari (dinotefuran) as an industry standard (positive check), LALGuard M52 (Metarhizium brunneum-formerly M. anisopliae), Mainspring (cyantraniliprole), and Altus (flupyradifurone). A water-only treatment was included as a negative check. Treatments (5) were assigned to experimental units (field-grown trees, 4 m high) under a RCB with 6 replicates.

Each treated red maple tree had a 1 × 1 m mesh bag placed over the terminal end of the branch. The LaLGuard M52 treatment had 10 live adult SLF added prior to being zip cable-tied closed and treatment applied. The other treatments were made, and then the SLF were added to the bags prior to being zip cable-tied. The cable ties were used to prevent adult escape. The trees were grown in clay loam soils with a pH between 6.0 and 6.5. Treatments were applied with a CO₂ sprayer at 35 psi.

Treatments were evaluated 3 days after treatment (5 DAT; 4 September 2023). The bags had the cable tie removed and the number of living and dead SLF were counted. Some of the bags had less than 10 insects inside when post-treatment counts were made. Insects found in the mesh bags at the conclusion of the experiment could be either alive or dead; consequently, a binomial error distribution was used to determine how significant the differences were between treatments. The percent mortality was analyzed using binomial regression with insecticide treatment as the explanatory factor and pairwise means comparisons were done using Tukey’s honestly significant difference (HSD) tests.

Application using a CO₂ sprayer provided sufficient coverage of foliage through the mesh bags to provide significant control of adult SLF. This was determined in a pretrial calibration where we placed nets on branches, attached a water-sensitive spray card inside of the net, and recorded how much solution (in the calibration case, water) was applied to attain full coverage. This volume was used as the total spray volume of insecticide solution sprayed per branch. Our results found Mainspring, Altus, and Safari (check) had mortality rates significantly higher than the untreated control (Table 1). LaLGuard M52 did not provide significantly greater mortality than untreated controls and specimens sent to the laboratory to examine for fungal growth showed no signs of fungal growth. This project found insecticides other than neonicotinoids could be effective at managing adult SLF populations.¹

Table 1.

Treatment	Chemical	Rate/Liter	Percent mortality
Untreated	Water	n/a	31.7b
Safari 20 SG (check)	Dinotefuran	0.6 g	98.3a
LaLGuard M52	Metarhizium brunneum	2.8 ml	47.4b
Mainspring GNL	Cyantraniliprole	1.25 ml	95.0a
Altus	Flupyradifurone	3.0 ml	96.7a
P > F			<0.001

Means within columns followed by a common letter are not significantly different (P < 0.001, Tukey HSD).

Footnotes

1

This research was supported in part by industry gifts of pesticides and/or research funding.