The spotted lanternfly (Lycorma delicatula) is an invasive insect of significant global concern. Native to Asia, it was first detected in the U.S. in Pennsylvania in 2014. It has since rapidly spread, threatening agriculture, forests, and ornamental plants. Its rapid spread raises questions about natural enemies and population control in its native habitat.
Generalist Predators in Invaded Regions
Native generalist predators in invaded regions opportunistically feed on spotted lanternflies. Birds like chickens, cardinals, blue jays, and tufted titmice consume them. Various arthropods also prey on them, including praying mantises, spiders, assassin bugs, and wheel bugs.
Despite these observations, the impact of generalist predators on overall spotted lanternfly populations is typically minimal. These predators feed on a wide variety of prey, and the spotted lanternfly does not constitute a significant portion of their diet. Their sheer numbers and rapid reproduction often overwhelm any localized control.
Specialized Natural Enemies from Native Habitats
In its native Asia, specialized natural enemies that co-evolved with the spotted lanternfly naturally regulate its populations. Parasitic wasps are particularly effective. Anastatus orientalis, an egg parasitoid wasp, lays its eggs inside lanternfly egg masses. This parasitoid achieves high rates of parasitism, significantly reducing lanternfly numbers.
Fungal pathogens also control spotted lanternfly populations in their native environment. Notable entomopathogenic fungi include Beauveria bassiana and Batkoa major. These fungi infect insects upon contact, leading to death. Both have caused significant mortality, with Batkoa major showing high efficacy. These specialized natural enemies are crucial for keeping spotted lanternfly populations in check within their native ecosystems.
Factors Limiting Natural Control
The lack of effective natural control in invaded regions stems primarily from the absence of these co-evolved specialized natural enemies. Unlike in Asia, the parasitoids and fungal pathogens that specifically target the spotted lanternfly are not present in sufficient numbers, or at all, in newly invaded areas. This ecological void allows the spotted lanternfly to reproduce and spread without the natural population pressures it faces in its homeland.
The spotted lanternfly also possesses several defensive mechanisms that limit the impact of generalist predators. It can sequester toxic compounds from its preferred host plant, the tree of heaven (Ailanthus altissima), which may make it unpalatable or even harmful to some predators. Additionally, the insect exhibits behavioral defenses such as rapid jumping and displaying its bright hindwings, which can startle potential attackers. Coupled with its high reproductive rate, these factors enable spotted lanternfly populations to rapidly expand in invaded territories.
Targeted Biocontrol Research
Scientists are actively researching and developing targeted biological control methods to manage spotted lanternfly populations in invaded areas. A primary focus involves identifying and safely introducing specialized natural enemies from the spotted lanternfly’s native range. Anastatus orientalis is a leading candidate due to its high rates of parasitism on spotted lanternfly eggs in China and South Korea.
The introduction of any new biological control agent requires rigorous testing to ensure it is host-specific and will not harm non-target native species or ecosystems. This multi-year process involves extensive evaluation in controlled quarantine facilities to assess potential risks. If deemed safe and effective, the strategic release of agents like Anastatus orientalis could provide a long-term, sustainable solution for regulating spotted lanternfly populations.