Discovery of two hypocrealean fungi infecting spotted lanternflies, Lycorma delicatula: Metarhizium pemphigi and a novel species, Ophiocordyceps delicatula

Two new species and one new combination of Ophiocordyceps (Hypocreales, Ophiocordycipitaceae) in Guizhou

Ophiocordyceps is the largest genus in Ophiocordycipitaceae and has a broad distribution with high diversity in subtropical and tropical regions. In this study, two new species, pathogenic on lepidopteran larvae are introduced, based on morphological observation and molecular phylogeny. Ophiocordycepsfenggangensissp. nov. is characterised by having fibrous, stalked stroma with a sterile tip, immersed perithecia, cylindrical asci and filiform ascospores disarticulating into secondary spores. Ophiocordycepsliangiisp. nov. has the characteristics of fibrous, brown, stipitate, filiform stroma, superficial perithecia, cylindrical asci and cylindrical-filiform, non-disarticulating ascospores. A new combination Ophiocordycepsmusicaudata (syn. Cordycepsmusicaudata) is established employing molecular analysis and morphological characteristics. Ophiocordycepsmusicaudata is characterised by wiry, stipitate, solitary, paired to multiple stromata, yellowish, branched fertile part, brown stipe, immersed perithecia, cylindrical asci and cylindrical-filiform, non-disarticulating ascospores.

Accumulation of Fungal Pathogens Infecting the Invasive Spotted Lanternfly, Lycorma delicatula

In the eastern United States, populations of the invasive spotted lanternfly, Lycorma delicatula, are abundant and spreading. Four species of naturally occurring entomopathogenic fungi have previously been reported as infecting these planthoppers, with two of these causing epizootics. Nymphal- and adult-stage lanternflies in Pennsylvania and New York were surveyed for entomopathogenic fungal infections from October 2021 to November 2023, and assays were conducted to confirm the pathogenicity of species that were potentially pathogenic. Beauveria bassiana was the most abundant pathogen, but we report an additional 15 previously unreported species of entomopathogenic fungi infecting spotted lanternflies, all in the order Hypocreales (Ascomycota). The next most common pathogens were Fusarium fujikuroi and Sarocladium strictum. While infection prevalence by species was often low, probably impacted to some extent by the summer drought in 2022, together these pathogens caused a total of 6.7% mortality. A significant trend was evident over time within a season, with low levels of infection among nymphs and higher infection levels in mid- and late-stage adults, the stages when mating and oviposition occur.

Evaluating integrated pest management tactics for spotted lanternfly management in vineyards

BACKGROUND

Spotted lanternfly, an invasive planthopper which was first found in 2014 in the eastern USA, has become a significant pest to vineyards. Sap-feeding by this pest has been associated with plant stress and yield declines, and current management depends entirely on the prophylactic use of insecticides. Our study explored two new integrated pest management (IPM) tactics against spotted lanternfly to reduce the negative effects of frequent chemical applications: the use of exclusion netting and the use of perimeter applications of insecticides.

RESULTS

Exclusion netting was installed across five vineyards in 2020 and compared to adjacent vines without exclusion netting. The netting reduced spotted lanternfly on vines by 99.8% and had no effect on air temperature, humidity, fungal disease pressure, or fruit quality. Perimeter applications of insecticides were compared against full-cover applications for both in-season and late-season control of spotted lanternfly in 2020. Residual efficacy with adult spotted lanternfly was evaluated within the vineyard plots, revealing that insecticide efficacy declined after 8 m into the vineyard in the perimeter application. However, there was no difference in the level of control achieved using a perimeter spray compared to a full-cover spray. Additionally, the perimeter spray reduced the area treated with insecticide by 31% in a 1 ha block and took 66% less time to spray.

CONCLUSION

Both methods, exclusion netting and perimeter spraying, offer new strategies to alleviate the invasion of spotted lanternfly into vineyards, reducing chemical input and rebuilding IPM in vineyards after invasion by spotted lanternfly. © 2023 Society of Chemical Industry.

Cryptic diversity and virulence of Beauveria bassiana recovered from Lycorma delicatula (spotted lanternfly) in eastern Pennsylvania

The entomopathogenic fungus Beauveria bassiana is cosmopolitan and known to infect a variety of sap-sucking pests like aphids, mealybugs, and scales in the order of Hemiptera. In Fall 2017, spotted lanternfly (SLF) adults killed by the fungal entomopathogen B. bassiana were found in Berks County, Pennsylvania. In 2018-2020 we collected SLF and nearby non-target insects killed by Beauveria spp. from 18 field sites in southeastern Pennsylvania. We identified 159 Beauveria isolates from SLF and six isolates from non-targets. Five isolates of B. bassiana and one isolate of B. brongniartii were identified from the non-targets. Based on sequence data from the nuclear B locus (Bloc) intergenic region, all the isolates from SLF were identified as B. bassiana, but there were 20 different strains within this species, grouped into two clades. Three B. bassiana strains (A, B, and L) were found in most field sites and were the most prevalent. Representative isolates for these three strains were used in laboratory bioassays and were compared to a commercial B. bassiana strain (GHA). Strain B was inferior to A, L, and GHA against nymphs; strains A and L had greater efficacy than B and GHA against adults. We also quantified conidial production on SLF cadavers. This paper discusses the diversity of these B. bassiana strains in SLF populations and implications for biological control of this abundant invasive.

Pathogen evasion of social immunity

Treating sick group members is a hallmark of collective disease defence in vertebrates and invertebrates alike. Despite substantial effects on pathogen fitness and epidemiology, it is still largely unknown how pathogens react to the selection pressure imposed by care intervention. Using social insects and pathogenic fungi, we here performed a serial passage experiment in the presence or absence of colony members, which provide social immunity by grooming off infectious spores from exposed individuals. We found specific effects on pathogen diversity, virulence and transmission. Under selection of social immunity, pathogens invested into higher spore production, but spores were less virulent. Notably, they also elicited a lower grooming response in colony members, compared with spores from the individual host selection lines. Chemical spore analysis suggested that the spores from social selection lines escaped the caregivers' detection by containing lower levels of ergosterol, a key fungal membrane component. Experimental application of chemically pure ergosterol indeed induced sanitary grooming, supporting its role as a microbe-associated cue triggering host social immunity against fungal pathogens. By reducing this detection cue, pathogens were able to evade the otherwise very effective collective disease defences of their social hosts.

Biology and Management of the Spotted Lanternfly, Lycorma delicatula (Hemiptera: Fulgoridae), in the United States

Spotted lanternfly, Lycorma delicatula (White), invaded the eastern United States in 2014 and has since caused economic and ecological disruption. In particular, spotted lanternfly has shown itself to be a significant pest of vineyards and ornamental plants and is likely to continue to spread to new areas. Factors that have contributed to its success as an invader include its wide host range and high mobility, which allow it to infest a wide range of habitats, including agricultural, urban, suburban, and managed and natural forested areas. Management is dependent on chemical use, although no single currently available control measure alone will be sufficient.