Enhanced Mitigation and Rapid Response to Reduce Spread and Impact of Spotted Lanternfly in the United States

Photo Credit

USDA Forest Service photo by Melody Keena.

An adult spotted lanternfly on a tree trunk.

The spotted lanternfly, Lycorma delicatula (White) (Hemiptera: Fulgoridae), is an invasive species of planthopper that was first detected in the United States in the summer of 2014. Spotted lanternfly is native to China, Vietnam, and India; the United States is one of three countries recently invaded by this species, together with Japan and South Korea. Since its initial detection in Pennsylvania, spotted lanternfly has spread across the northeastern region of the United States and is now established in multiple states.

Spotted lanternfly has four growth stages, which scientists refer to as “instars”. The first-instar nymphs start to emerge from eggs in late April in North America. Nymphs of the first three instars are black and white, and fourth-instar nymphs are black, white, and red in color. Adults appear around mid-July and lay eggs from early September until temperatures are low enough to kill them. The eggs are deposited in grayish to tan-colored egg masses on a variety of surfaces including bark, stone, wood fences, and brick. Egg masses remain dormant until the following spring.

Spotted lanternfly has a broad host range consisting of 103 plant species. Despite this, spotted lanternfly has a preferred host, which is the tree of heaven, Ailanthus altissima (another invasive species in the United States). Recently, it was found that spotted lanternfly does not require tree of heaven to complete its lifecycle, but that the removal of tree of heaven from its diet is associated with reduced fitness.

Photos

Key Findings

• We have found that there is substantial variation in thermal response across the invaded range that may allow spotted lanternfly to adapt to a broad range of climates.
• The potential geographic range of spotted lanternfly nymphs may be broader than previously predicted.

The temperature of the surrounding environment has a major influence on insects and can impact physiology, development, and growth. As insects tend to be adapted for the climate in their native range, exposure to temperatures outside of this range in invaded habitats can have unknown results. We need data to create broadly applicable phenology models that assess the response of spotted lanternfly populations to a broad range of temperatures and hosts. These models are needed to support three key tasks, including:

1. Identify when to monitor for spotted lanternfly,
2. Predict the timing of life-stages suitable for control measures, and
3. To identify the regions of the United States that provide suitable conditions for spotted lanternfly populations and are therefore at risk to invasion by this species.

We are conducting additional work on temperature treatments that could reduce the spread of the insect by preventing eggs laid on vehicles or shipping containers from hatching. Other research is exploring the use of prescribed fire to control spotted lanternfly egg mass survival.

We have compiled the basic data needed to produce an agent-based phenology model for spotted lanternfly using a structure developed for other invasive insects. This includes upper and lower temperatures for each stage of growth and records how the spotted lanternfly responds to temperatures between 5˚ and 40˚ C. It also includes the responses of eggs in the spring to temperature so we can predict hatch.

We have also assessed the effects of host plants on how fast the spotted lanternfly develops.

We collected validation data sets of actual development of spotted lanternfly in the field and in laboratory under normal daily alternating temperatures.

We have assessed the effects of cold snaps and heat waves on spotted lanternfly life stages and found that they can still develop when temperatures above and below the estimated limits are part of a daily alternating thermal cycle.

We are currently completing work on the within and between population differences in hatch timing and development of early instars to incorporate the full diversity into the model and assess their ability to adapt to new climates. We have found that there is substantial variation in thermal response across the invaded range that may allow them to adapt to a broad range of climates. We have evidence that spotted lanternfly are adapting to regional temperature variations and may have a greater potential geographic range in North America than previously believed.

We are assessing the timing of egg laying and the effects of when the eggs are laid on when they will hatch the next spring.

We are just starting work to identify the environmental cues that determine when spotted lanternfly eggs enter and exit the winter dormant stage. This ongoing work will help fill gaps in knowledge and improve prediction of egg hatch for novel climates and for egg masses that are transported to new habitats via shipping containers or vehicles.

We are also working on treatments that can be applied to material infested with egg masses that will kill the eggs and make it safe to transport to uninfested areas.