A benefit-risk analysis for biological control introductions based on the protection of native biodiversity.

The release of biological control agents has been an important means of controlling invasive species for over 150 years. While these releases have led to the sustainable control of over 250 invasive pest and weed species worldwide, a minority have caused environmental harm. A growing recognition of the risks of biological control led to a focus on risk assessment beginning in the 1990s along with a precipitous decline in releases. While this new focus greatly improved the safety of biological control, it came at the cost of lost opportunities to solve environmental problems associated with invasive species. A framework that incorporates benefits and risks of biological control is thus needed to understand the net environmental effects of biological control releases. We introduce such a framework, using native biodiversity as the common currency for both benefits and risks. The model is based on interactions among four categories of organisms: (1) the biological control agent, (2) the invasive species (pest or weed) targeted by the agent, (3) one or more native species that stand to benefit from the control of the target species, and (4) one or more native species that are at risk of being harmed by the released biological control agent. Conservation values of the potentially benefited and harmed native species are incorporated as well, and they are weighted according to three axes: vulnerability to extinction, the ecosystem services provided, and cultural significance. Further, we incorporate the potential for indirect risks to native species, which we consider will result mainly from the ecological process of agent enrichment that may occur if the agent exploits but does not control the target pest or weed. We illustrate the use of this framework by retrospectively analyzing the release of the vedalia beetle, Novius (= Rodolia) cardinalis, to control the cottony cushion scale, Icerya purchasi, in the Galapagos Islands. While the framework is particularly adaptable to biological control releases in natural areas, it can also be used in managed settings, where biological control protects native species through the reduction of pesticide use.

Detection of Ochyromera ligustri (Coleoptera: Curculionidae: Curculioninae) in Ligustrum spp. (Oleaceae) Using Newly Developed PCR Primers.

Ligustrum spp. (Oleaceae) have become invasive species in the US and negatively affect native plant diversity and richness in forests. Ochyromera ligustri (Coleoptera: Curculionidae) is considered a potential biological control agent in the US because adults feed on the foliage and larvae are seed-feeders of Ligustrum spp. To discover the relationships between O. ligustri and Ligustrum spp., fruit dissections or rearing and field observations are required. In the current research project, novel PCR primers were developed to rapidly detect the DNA of O. ligustri in molecular analyses without rearing and observation. The developed PCR primers worked even with 0.01 ng of DNA and did not amplify the DNA of the other five curculionid species tested. When the novel primers were tested with three Ligustrum spp. species common in the southeastern US, the DNA of O. ligustri was detected from all three species. We expect that the novel primers will be utilized to find out the presence and impact of O. ligustri on Ligustrum spp rapidly and accurately.

Exploiting exotic pathogens as mycoherbicides against invasive alien weeds: Japanese knotweed as a case study.

Plant species have been introduced increasingly into non-native ranges, where many have become exotic weeds with adverse impacts on native ecosystems, as well as on farming and other livelihoods. In biological control, the classical or inoculative approach is the one most commonly used for the management of invasive alien weeds and is based on the use of co-evolved natural enemies from the native range to control the invasive weed. Typically, the inundative or mycoherbicide approach targets problematic weeds using local plant pathogens that, in the case of introduced species, have 'jumped' onto the exotic host. The leaf-spot fungus, Mycosphaerella polygoni-cuspidati, co-evolved with its host, Reynoutria (Fallopia) japonica (Japanese knotweed), in Japan and has a unique history of being investigated both as a classical biological control agent and a mycoherbicide against this highly invasive weed in the United Kingdom and North America. Here, we highlight our research on M. polygoni-cuspidati as part of a biological control programme for Japanese knotweed and review the potential of mycoherbicides using exotic pathogens for the management of invasive alien weeds. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Climate suitability analyses compare the distributions of invasive knotweeds in Europe and North America with the source localities of their introduced biological control agents.

Climate suitability analyses based on ecological niche modeling provide a powerful tool for biological control practitioners to assess the likelihood of establishment of different candidate agents prior to their introduction in the field. These same analyses could also be performed to understand why some agents establish more easily than others. The release of three strains of Aphalara itadori (Shinji) (Hemiptera: Pysllidae), each from a different source locality in Japan, for the biological control of invasive knotweed species, Reynoutria spp. Houtt. (Caryophyllales: Polygonaceae), provides an important opportunity to compare the utility of climate suitability analyses for identifying potential climate-based limitations for successful biological control introductions. Here, we predict climate suitability envelopes for three target species of knotweed in Europe and two target species of knotweed in North America and compare these suitability estimates for each of these species to the source localities of each A. itadori strain. We find that source locality of one strain, the Kyushu strain, has little-to-no suitability compared to other locations in Japan based on knotweed records from Europe, supporting an earlier study based on North American Japanese knotweed records. The source locality of a second strain, the Murakami strain, was predicted to have medium-to-high suitability based on records of knotweeds from North America. In contrast, European records of Reynoutria × bohemica Chrtek & Chrtková and Reynoutria sachalinensis (F. Schmidt) Nakai predicted no suitability for this locality compared to other locations in Japan, while European records for Reynoutria japonica Houtt. predicted low suitability. The source locality of the final strain, the Hokkaido strain, was predicted as having medium-to-high suitability based on knotweed records of all examined species from both North America and Europe.

Reassessing the presence of alien predatory mites and their prospects in the face of future climate change.

BACKGROUND: Climate change poses uncertainties in the effectiveness of classical biological control (CBC), and there is a lack of information on the establishment of natural enemy populations under present and future climatic conditions. The objective is to explore current traces of two alien predators (Neoseiulus californicus and Neoseiulus fallacis; introduced for the CBC program in the 1980s) and their future expansion under climate change in Taiwan. RESULTS: The results indicated that N. californicus was present in alpine orchards (e.g., Lishan and Meifeng) but N. fallacis was not found. Under current climate condition, most areas in Taiwan were deemed highly suitable for N. californicus, but not for N. fallacis, which may explain the outcomes of the CBC program. With intensifying climate change, the ranges of both species are projected to contract to varying extents in Taiwan but expand in some countries. CONCLUSION: The findings from this study can provide insights for evaluating and developing future CBC programs worldwide, and can help predict the implications of climate change on biological control efforts. © 2023 Society of Chemical Industry.

Successful establishment, spread, and impact of the introduced parasitoid Spathius galinae (Hymenoptera: Braconidae) on emerald ash borer (Coleoptera: Buprestidae) populations in postinvasion forests in Michigan.

Spathius galinae is a larval parasitoid native to the Russian Far East that was approved for release in the United States in 2015 for biological control of the emerald ash borer (EAB), Agrilus planipennis, an invasive beetle from Asia responsible for widespread mortality of ash trees (Fraxinus spp.) in North America. From 2015 to 2017, 1,340-1,445 females of S. galinae along with males were released into each release plot, paired with a nonrelease control plot (1-12.5 km apart), at 6 postinvasion forested sites containing abundant pole-sized ash trees in Michigan. By 2018, S. galinae had spread to all but one control plot. Based on the first year that S. galinae was found in trees in each control plot and the distances of those trees to the parasitoid release point within each site, we estimated that S. galinae spread at 3.7 (±1.9) km per year after its initial releases in 2015. The proportion of sampled trees with S. galinae broods, brood densities within sampled trees, and parasitism of EAB larvae increased sharply in both control and release plots after the last field releases in 2017, with the highest parasitism rates (42.8-60.3%) in 2020. Life table analysis showed that S. galinae alone reduced EAB's net population growth rate by 35-55% across sites from 2018 to 2020. These results demonstrate that S. galinae has established an increasing population in Michigan and now plays a significant role in reducing EAB populations in the area.

Surveying potentially antagonistic fungi to myrtle rust (Austropuccinia psidii) in Brazil: fungicolous Cladosporium spp.

The myrtle rust (MR), caused by Austropuccinia psidii, is a worldwide threat to the cultivated and wild Myrtaceae. Originally from the neotropics, it has spread to North America, Africa, and Asia and has reached geographically isolated areas in the Pacific and Australasia. It is attacking native species in those new ranges and is still spreading and causing great concern for the damage caused to endemic Myrtaceae, and to the environment. Classical biological control is regarded as the most sustainable management option for mitigating such biological invasions. However, there are no examples of introductions of host-specific co-evolved natural enemies of plant pathogens, from their native range, as a management strategy for plant pathogens. In order to explore this neglected approach, a survey of potential fungal natural enemies of A. psidii was initiated recently in the state of Minas Gerais (Brazil). Several purported mycoparasites have been collected from A. Psidii pustules formed on myrtaceous hosts. This included some isolates of dematiaceous fungi recognized as having a Cladosporium-like morphology. Here we present the results of the investigation aimed at elucidating their identity through a polyphasic taxonomic approach. Besides morphological and cultural features, molecular analyses using sequences of translation elongation factor 1-α (EF1) and actin (ACT) were performed. The combination of data generated is presented herein and placed all Cladosporium-like isolates in six species of Cladosporium, namely, Cladosporium angulosum, C. anthropophilum, C. bambusicola, C. benschii, C. guizhouense, and C. macadamiae. None of these have ever been recorded in association with A. psidii. Now, with the identification of these isolates at hand, an evaluation of biocontrol potential of these fungi will be initiated. In contrast with the ready finding of fungicolous (possibly mycoparasitic) fungi on MR in this study, no evidence of those was recorded from Australasia until now.

Accessing biological control genetic resources: the United States perspective.

The USA has been actively involved in classical biological control projects against invasive insect pests and weeds since 1888. Classical (importation) biological control relies upon natural enemies associated through coevolution with their target species at their geographic origin to also provide long-term, self-sustaining management where the pest/weed has become invasive. Biological control agents are a form of genetic resources and fall under the purview of the 1993 Convention on Biological Diversity (CBD) and its Nagoya Protocol (NP), which entered into force in 2014 to address equitable sharing of benefits arising from utilization of genetic resources. Safe and effective classical biological control agents have historically been shared among countries experiencing problems with invasive species. However, a feature of the Nagoya Protocol is that countries are expected to develop processes governing access to their genetic resources to ensure that the benefits are shared equitably-a concept referred to as "access and benefit sharing" (ABS). Although the USA is not party to the CBD nor the NP, US biological control programs are affected by these international agreements. Surveying, collecting, exporting and importing of natural enemies may be covered by new ABS regulatory processes. Challenges of ABS have arisen as various countries enact new regulations (or not) governing access to genetic resources, and the processes for gaining access and sharing the benefits from these resources have become increasingly complex. In the absence of an overarching national US policy, individual government agencies and institutions follow their own internal procedures. Biological control practitioners in the USA have been encouraged in recent years to observe best practices developed by the biological community for insect and weed biological control.

Disentangling thermal effects using life cycle simulation modelling on the biology and demographic parameters of Dolichogenidea gelechiidivoris, a parasitoid of Tuta absoluta.

Dolichogenidea gelechiidivoris (Marsh) (Syn. Apanteles gelechiidivoris) (Hymenoptera: Braconidae), a konoibiont larval endoparasitoid of the South American tomato pinworm Tuta absoluta (Meyrick), was imported into Kenya in 2017 for the first classical biological control of T. absoluta in Africa. We determined the thermal thresholds of D. gelechiidivoris, with T. absoluta as host, using life cycle simulation modelling. Life-table data of D. gelechiidivoris were generated at six constant temperatures (10, 15, 20, 25, 30, and 35 °C, 65 ± 5% RH, and 12L: 12D photoperiod). Multiple non-linear functions were fitted to model some aspects of the biology of the parasitoid, including its longevity, mortality, reproduction, and senescence using Insect Life Cycle Modelling (ILCYM) software. The phenology models established were used to estimate life table parameters. Except at 35 °C, D. gelechiidivoris completed its development (i.e., egg-larval-pupa-adult) at all tested temperatures. The minimum temperature threshold from egg to cocoon was 7.0 °C and 5.9 °C from cocoon to adult wasp, while the maximum temperature thresholds were 34 °C and 36 °C, respectively. The optimal temperature for immature survival was 20-25 °C, while fecundity was optimum at 22.5 °C, with 69.5 eggs per female. Simulations of the population growth parameters indicated that the intrinsic rate of increase (rm) was maximum at 20 °C with 15 daughters per female per generation. Based on our findings the release of D. gelechiidivoris for inoculative augmentation in countries with temperatures ranging between 15 and 30 °C could be considered to control the pest.

Predation and Climate Limit Establishment Success of the Kyushu Strain of the Biological Control Agent Aphalara itadori (Hemiptera: Aphalaridae) in the Northeastern United States.

Species of knotweeds, Reynoutria spp. Houtt. (Caryophyllales: Polygonaceae), including Japanese knotweed (R. japonica Houtt.), are among the most invasive and ecologically destructive plant species introduced to North America and Europe. The Kyushu strain of the psyllid Aphalara itadori Shinji (Hemiptera: Aphalaridae) has been approved as a biological control agent for release against Japanese knotweed in the United Kingdom, Canada, and the United States. However, recent reports from Canada suggest that both biotic and abiotic factors may limit its establishment. Therefore, we examined the potential role of predation by comparing open- versus closed-sleeve treatments, and climate mis-matches by collecting temperature data from release sites and performing climate suitability analyses using MaxEnt. Our results indicated that populations of the Kyushu strain could only be maintained in the field in closed-sleeve treatments, suggesting that predation is likely limiting the establishment success of this strain. In addition, we noted that daily maximum temperatures at our field sites might exceed documented developmental thresholds for this strain, and that MaxEnt species distribution modeling indicates no climate similarities between locations in eastern North America and Kyushu. Combined with previous results, our study suggests that the establishment of the Kyushu strain of A. itadori as a biological control agent for Japanese knotweed may be limited in eastern North America. We suggest that one strategy to increase the probability of establishment of the Kyushu strain could be to increase the number of release sites in an effort to find a more optimal niche with predator-free space.

Combining photoperiod and thermal responses to predict phenological mismatch for introduced insects.

A wide variety of organisms use the regular seasonal changes in photoperiod as a cue to align their life cycles with favorable conditions. Yet the phenological consequences of photoperiodism for organisms exposed to new climates are often overlooked. We present a conceptual approach and phenology model that maps voltinism (generations per year) and the degree of phenological mismatch that can arise when organisms with a short-day diapause response are introduced to new regions or are otherwise exposed to new climates. Our degree-day-based model combines continent-wide spatialized daily climate data, calculated date-specific and latitude-specific day lengths, and experimentally determined developmental responses to both photoperiod and temperature. Using the case of the knotweed psyllid Aphalara itadori, a new biological control agent being introduced from Japan to North America and Europe to control an invasive weed, we show how incorporating a short-day diapause response will result in geographic patterns of attempted voltinism that are strikingly different from the potential number of generations based on degree-days alone. The difference between the attempted and potential generations represents a quantitative measure of phenological mismatch between diapause timing and the end of the growing season. We conclude that insects moved from lower to higher latitudes (or to cooler climates) will tend to diapause too late, potentially resulting in high mortality from inclement weather, and those moved from higher to lower latitude (to warmer climates) may be prone to diapausing too early, therefore not fully exploiting the growing season and/or suffering from insufficient reserves for the longer duration in diapause. Mapped output reveals a central region with good phenology match that shifts north or south depending on the geographic source of the insect and its corresponding critical photoperiod for diapause. These results have direct relevance for efforts to establish populations of classical biocontrol agents. More generally, our approach and model could be applied to a wide variety of photoperiod- and temperature-sensitive organisms that are exposed to changes in climate, including resident and invasive agricultural pests and species of conservation concern.

Plant pathogens as introduced weed biological control agents: Could antagonistic fungi be important factors determining agent success or failure?

Mycoparasitic interactions are common in nature, form part of the microbiota of plants, and are considered significant contributors to fungus-fungus antagonism. Mycoparasites kill plant pathogens, protect the plant from abiotic and biotic stressors, and reduce disease incidence and severity at the plant population level. Their exploitation as biocontrol agents in agriculture is well documented. However, mycoparasites may potentially affect classical fungal biocontrol agents of invasive weed species. Classical biological control, or biocontrol, of invasive weeds involves the intentional introduction of exotic, usually co-evolved plant pathogens and insects, for permanent establishment and long-term control of the target plant. Agent establishment, effectiveness, and safety are the critical elements for a successful weed biocontrol programme. Establishment and effectiveness of agents on the invasive plant often vary throughout the invaded range with about two-thirds of weed biocontrol agents failing to suppress their target weed. There are many documented reasons why weed biocontrol agents do not establish or are ineffective when they do, and the presence and accumulation of natural enemies in the invaded range is one of them. Endophyte-enriched, invasive weeds and those forming mutualistic associations with indigenous, native endophytes could explain the lack of consistency of some classical biological control introductions. However, another variable could be factored into the mix: mycoparasitism, where one fungus parasitises another, the natural enemies of the plant's natural enemies. In this review article, we introduce the concept of invasive weed biocontrol and the history of using plant pathogens as biocontrol agents. We discuss the success and failure of fungal agent programmes and delve into the patterns of success or failure, with a focus on the potential antagonistic role of endophytes and mycoparasites.

Rapid Spread of an Introduced Parasitoid for Biological Control of Emerald Ash Borer (Coleoptera: Buprestidae) in Maryland.

Emerald ash borer (Agrilus planipennis Fairmaire (Coleoptera: Buprestidae)), an invasive phloem-feeding beetle native to Asia, has devastated North American ash forests since its detection in Michigan, United States in 2002. As the emerald ash borer has continued to spread, the potential for successful long-term management hinges upon the release, establishment, and spread of introduced larval and egg parasitoids for biological control. Here, we focus on the establishment and evidence for spatial spread of introduced larval parasitoid, Spathius agrili Yang and Spathius galinae Belokobylskij & Strazanac (Hymenoptera: Braconidae) in the state of Maryland. To assess each species, we analyzed historical release and recovery data and resampled previous release sites and nonrelease sites for establishment. We found little evidence of establishment or spread for S. agrili, despite a comparatively large number of release locations, events, and individuals. By contrast, despite much lower propagule pressure and shorter history of releases, we detected multiple established populations of S. galinae at release sites and at sites up to 90 km from the nearest release point approximately 3 yr after its most current release. Our findings show that S. galinae has established and spread rapidly following field releases whereas its congener, S. agrili has not. Although it may still be too early to evaluate the level of population control and ash protection afforded by S. galinae, these findings indicate the need for continued investment in S. galinae for emerald ash borer classical biological control efforts.

Revealing the Introduction History and Phylogenetic Relationships of Passiflora foetida sensu lato in Australia.

Genomic analysis can be a valuable tool to assistmanagement of non-native invasive species, through determining source and number of introductions as well as clarifying phylogenetic relationships. Here, we used whole chloroplast sequencing to investigate the introduction history of Passiflora foetida sensu lato in Australia and clarify its relationship with other Passiflora species present. Phylogenetic analysis of chloroplast genome data identified three separate genetic lineages of P. foetida s. l. present in Australia, indicating multiple introductions. These lineages had affinities to samples from three separate areas within the native range in Central and South America that represented phylogenetically distinct lineages. These results provide a basis for a targeted search of the native range of P. foetida s. l. for candidate biological control agents that have co-evolved with this species and are thus better adapted to the lineages that are present in Australia. Results also indicated that the Passiflora species native to Australia are in a separate clade to that of P. foetida s. l. and other introduced Passiflora species cultivated in Australia. This knowledge is important to assess the likelihood of finding biological control agents for P. foetida s. l. that will be sufficiently host-specific for introduction in Australia. As P. foetida s. l. is a widespread non-native invasive species across many regions of the world, outcomes from this work highlight the importance of first evaluating the specific entities present in a country before the initiation of a biological control program.

Taxonomic Description of Stenodiplosis tectori n. sp. (Diptera: Cecidomyiidae), a Seed Parasite of Cheatgrass, Anisantha tectorum, Based on Morphological and Mitochondrial DNA Data.

Cheatgrass is an annual grass species from Eurasia that has become invasive in much of western North America. It has been implicated in recent increases in the frequency, size, and intensity of wildfires, contributing to severe economic, environmental, and social destruction. In order to reduce this damage, the USDA-ARS established a classical biological control program against cheatgrass. In 2018 and 2019, adult gall midges were collected emerging from cheatgrass seed heads collected at several sites in Bulgaria and Greece; this is the first gall midge ever recorded from cheatgrass. Morphological comparisons with related midge species recorded from other plant hosts revealed that this midge from cheatgrass is a new species, described here as Stenodiplosis tectori n. sp. This status was supported by sequence comparisons of a barcode region of the gene encoding the mitochondrial cytochrome c subunit I (CO1) protein in Stenodiplosis tectori n. sp. and three congeners. The present study is the first to report MT-CO1 data in the genus Stenodiplosis. The ingroup Stenodiplosis tectori n. sp. collected in the Balkans grouped in one phylogenetic supported clade, with an average K2P-distance from its closest related congener, S. sorghicola, of 7.73% (SD = 1.10). The findings indicated relatively high year-to-year within-population diversity. Implications for this gall midge's utility as a biological control agent of cheatgrass are discussed.

Optimal Conditions for Diapause Survival of Aprostocetus fukutai, an Egg Parasitoid for Biological Control of Anoplophora chinensis.

Aprostocetus fukutai is a specialist egg parasitoid of the citrus longhorned beetle Anoplophora chinensis, a high-risk invasive pest of hardwood trees. The parasitoid overwinters as diapausing mature larvae within the host egg and emerges in early summer in synchrony with the egg-laying peak of A. chinensis. This study investigated the parasitoid's diapause survival in parasitized host eggs that either remained in potted trees under semi-natural conditions in southern France or were removed from the wood and held at four different humidities (44, 75, 85-93 and 100% RH) at 11 °C or four different temperature regimes (2, 5, 10 and 12.5 °C) at 100% RH in the laboratory. The temperature regimes reflect overwintering temperatures across the parasitoid's geographical distribution in its native range. Results show that the parasitoid resumed its development to the adult stage at normal rearing conditions (22 °C, 100% RH, 14L:10D) after 6- or 7-months cold chilling at both the semi-natural and laboratory conditions. It had a low survival rate (36.7%) on potted plants due to desiccation or tree wound defense response. No parasitoids survived at 44% RH, but survival rate increased with humidity, reaching the highest (93.7%) at 100% RH. Survival rate also increased from 21.0% at 2 °C to 82.8% at 12.5 °C. Post-diapause developmental time decreased with increased humidity or temperature. There was no difference in the lifetime fecundity of emerged females from 2 and 12.5 °C. These results suggest that 100% RH and 12.5 °C are the most suitable diapause conditions for laboratory rearing of this parasitoid.

The Host Range and Risk Assessment of the Stem-Boring Weevil, Listronotus setosipennis (Coleoptera: Curculionidae) Proposed for the Biological Control of Parthenium hysterophorus (Asteraceae) in Pakistan.

Parthenium, or Parthenium hysterophorus, has extended its range in Pakistan throughout Punjab and into Khyber Pakhtunkhwa, the Federally Administrated Tribal Areas, Azad Jammu and Kashmir, and Sindh Provinces. Without control measures against parthenium, the negative impacts of this weed will go unchecked having deleterious effects on native biodiversity, human and animal health, as well as crop productivity. The weevil Listronotus setosipennis was obtained and imported from the Plant Health and Protection of the Agricultural Research Council (ARC-PHP), in Cedara, South Africa, in April 2019. A total of 22 plant species or cultivars in the Asteraceae family were assessed during no-choice oviposition tests in Pakistan. During these tests, the only plant species accepted for oviposition were the 10 cultivars of Helianthus annuus that are grown in Pakistan. All cultivars were thus tested for development of L. setosipennis from egg to adult. Only three cultivars were able to support some larval development, but at such low levels that it is unlikely to be the basis of a viable population. To support this, a risk assessment was conducted to ascertain the probability of L. setosipennis being able to sustain viable populations in the field, the results of which concur with native (Argentina) and introduced (Australia) field host-range information where L. setosipennis has never been recorded as a pest of sunflowers. The results of laboratory-based host-range trials, together with host records from its native and introduced range, indicate that L. setosipennis is sufficiently specific to parthenium and is thus suitable for release in Pakistan.

Successful biological control of winter moth, Operophtera brumata, in the northeastern United States.

Winter moth, Operophtera brumata, native to Europe, invaded the northeastern United States in the late 1990s, where it caused widespread defoliation of forests and shade trees ranging from 2,266 to 36,360 ha/yr between 2003 and 2015 in Massachusetts. In 2005, we initiated a biological control effort based on the specialist tachinid parasitoid Cyzenis albicans, which had previously been introduced along with the generalist ichneumonid parasitoid Agrypon flaveolatum to control winter moth in Nova Scotia in the 1950s and British Columbia in the 1970s. Due to concerns of possible non-target impacts by A. flaveolatum, we focused entirely on the specialist C. albicans. Each year for 14 yr, we collected several thousand individuals of C. albicans from British Columbia and released them in widely spaced sites in the northeastern United States. As of 2020, we had established C. albicans at 41 of 44 sites from coastal Maine to southeastern Connecticut. By 2016, winter moth densities (pupae/m2 ) had declined from 100-500 to 0-10 pupae/m2 at six release sites at least 10 km apart and this was coincident with the onset of 10-40% parasitism. At one site in Wellesley, Massachusetts, the decline occurred in 2012 and winter moth densities have remained low for seven subsequent years. Defoliation in Massachusetts has been reduced to undetectable levels by aerial survey since 2016. DNA sequencing of the barcoding region of the mitochondrial gene CO1 confirmed that all C. albicans reared from winter moth matched the C. albicans collected from Vancouver Island and were distinct from parasitic flies (presumably a native species) reared from a native congener of winter moth, Bruce spanworm (O. bruceata). Successful establishment of C. albicans on winter moth represents a rare, if not the only, example of the biological control of a major forest defoliator that attacks a wide range of tree species anywhere in the world by the establishment of a single specialist natural enemy.

A fungus-eat-fungus world: Digitopodium, with particular reference to mycoparasites of the coffee leaf rust, Hemileia vastatrix.

Digitopodium hemileiae was described originally in 1930 as Cladosporium hemileiae; growing as a mycoparasite of the coffee leaf rust (CLR), Hemileia vastatrix, in a sample of diseased leaves of Coffea canephora collected in the Democratic Republic of Congo. No cultures from this material exist. More recently, the type material was re-examined and, based on morphological features, considered to be incorrectly placed in Cladosporium. The new genus Digitopodium was erected to accommodate this species. Interest in fungal antagonists of H. vastarix, as potential biocontrol agents of CLR, led to comprehensive surveys for mycoparasites, both in the African centre of origin of the rust, as well as in its South American exotic range. Among the rust specimens from Ethiopia, one was found to be colonized by a fungus congeneric with, and similar to, D. hemileiae. Pure cultures obtained from the Ethiopian material enabled a molecular study and for its phylogenetic position to be elucidated, based on DNA sequence data from the ITS and LSU regions. Molecular data showed that two members of the recently erected genus Hyalocladosporiella (Herpotrichiellaceae: Chaetothyriales) are congeneric with Digitopodium from Ethiopia and morphologically similar to both D. hemileiae and the two Ethiopian isolates. These isolates were found to be morphologically and genetically identical to H. tectonae, described previously from Brazil. Thus, species of Hyalocladosporiella are re-allocated to Digitopodium here; including D. tectonae, and a novel species, D. canescens, recently found in Brazil growing as a mycoparasite of Puccinia thaliae. The potential use of D. hemileiae and D. tectonae for classical biological control of CLR is discussed.