Seasonal patterns of persistence and infectivity of Metarhizium anisopliae var. acridum in grasshopper cadavers in the Sahel

Field-based experiments were conducted to evaluate the fate and infectivity of the entomopathogenic fungus Metarhizium anisopliae var. acridum (Deuteromycotina: Hyphomycetes) in grasshopper cadavers in the Sahel. Unlike uninfected cadavers, which were rapidly scavenged, those infected with the fungus persisted in the environment for a number of weeks. The environmental factor most associated with cadaver disappearance was rainfall. The high environmental humidity associated with rainfall was also required for sporulation of the fungus on host cadavers, although the likelihood of sporulation differed between microsites. Characteristics of the infection profile from infective cadavers were investigated by the sequential exposure of uninfected hosts to sporulating cadavers in field cages. This experiment revealed that cadavers remained infective for > 30 days, with the net infectivity changing through time. The most likely explanation for these changes is climatic influences on both the fungus and host. High humidity was not required for infection. A measurement of the transmission coefficient between healthy hosts and sporulating cadavers in the field was obtained at a realistic density of infectious cadavers. This revealed a figure of 0.45 m² day^–1. Overall, these experiments show that following host death, M. anisopliae var. acridum can be persistent in the environment, sporulate on host cadavers and reinfect new hosts at a realistically low field density, although at least in arid or semi-arid areas, rainfall may be critical to the horizontal transmission of this pathogen.     

Effects of temperature and water activity on <Emphasis Type="Italic">Lecanicillium</Emphasis> spp. conidia germination and growth,and mycosis of <Emphasis Type="Italic">Pissodes strobi</Emphasis>

Selecting entomopathogenic fungal isolates for use as biocontrol agents requires an assessment of their growth and virulence characteristics as affected by environmental conditions. Here we demonstrate a wide temperature and moisture range for colony growth, effective conidial germination and virulence against Pissodes strobi Peck (white pine weevil) of several isolates of Lecanicillium Gams and Zare, an entomopathogenic fungus distributed worldwide and indigenous to forests on Vancouver Island, British Columbia, Canada. In order to examine the potential Lecanicillium as a biological control agent, the pathogenicity of isolates collected from different geographical locations on P. strobi cadavers was assessed, and colony growth at different temperatures was evaluated. Colony growth was evident between 5 and 30°C, with optimal growth occurring at 25°C. Various combinations of water activity (0.55, 0.76, 0.85 and 0.99 a _w) and temperature (10, 15, 20, and 25°C) were also used to evaluate environmental impacts on conidial germination and cumulative mycosis of adult P. strobi. Certain Lecanicillium isolates displayed xerophilic (0.85 a _w) or psychrophilic (10°C) growth optima. Ultimately, identifying the abiotic limits of this entomopathogenic fungus will be used to determine which isolates have potential for future in situ biocontrol trials.     

Isolation of basidiomycetous anamorphic yeast-like fungus <Emphasis Type="Italic">Meira argovae</Emphasis> found on Japanese bamboo

A basidiomycetous anamorphic yeast-like fungus, isolated from new bamboo shoots collected in Japan, was assigned to Meira argovae by comparison of conidial morphology, physiological characteristics, rDNA sequences, and DNA-DNA relatedness with the ex-type strains of Meira species. This is the first record of the finding of M. argovae from other than mite cadavers and in regions other than Israel. Phylogenetic analysis based on the D1-D2 domain demonstrated that Meira species and teleomorphic Dicellomyces species, which include a bamboo leaf parasite, D. gloeosporus, formed sister clades.     

Effects of Selected Fungicides and the Timing of Fungicide Application on Beauveria bassiana-Induced Mortality of the Colorado Potato Beetle (Coleoptera: Chrysomelidae)

Four fungicides used for controlling foliar diseases of potato (Solanum tuberosum) were evaluated under field and laboratory conditions for their effects on the infectivity and sporulation of Beauveria bassiana when used as a control for the Colorado potato beetle, Leptinotarsa decemlineata (CPB). We investigated the direct effects of fungicides on B. bassiana-induced CPB mortality and the effect of time between fungicide and B. bassiana application. Effects of fungicide on conidial survival in the soil and on foliage were examined in the field. Significantly more larval mortality was observed when larvae were sprayed with B. bassiana than with the water control. Fungicide had no significant effect on larval mortality in the field. In the laboratory, survival of larvae was significantly lower among larvae fed fungicide-treated foliage. B. bassiana-induced mortality in the laboratory was observed only when larvae were fed foliage treated with copper hydroxide or water. Larvae fed mancozeb- or chlorothalonil-treated foliage experienced high mortality regardless of B. bassiana treatment. While there was no significant effect of fungicide on B. bassiana sporulation on cadavers in the field, a pattern emerged that indicated higher proportions of cadavers producing conidia in plots sprayed with water or copper hydroxide than in plots sprayed with chlorothalonil or mancozeb. Survival of B. bassiana conidia in the soil and on foliage was significantly greater in plots treated with copper hydroxide or water than in plots treated with mancozeb or chlorothalonil. Fungicides such as copper hydroxide may be less deleterious to the fungus than mancozeb and chlorothalonil.     

A new species of <Emphasis Type="Italic">Discostroma</Emphasis> and its anamorph <Emphasis Type="Italic">Seimatosporium</Emphasis> with two morphological types of conidia,isolated from the stems of <Emphasis Type="Italic">Paeonia suffruticosa</Emphasis>

Conidia of two morphologically different types, one with a basal appendage only and the other with appendage at both ends, were isolated from the stems of Paeonia suffruticosa. Single conidial isolates of both types of conidia yield identical colonies, which then produced both types of conidia on agar media depending on temperature, thus showing that both types of conidia belong to the same fungus. Seimatosporium botan is described based on its morphological characteristics. The teleomorph of the fungus was first found on sterilized P. suffruticosa stems placed on water agar, when grown at 5°C for 2 months in 12-h photoperiod. Discostroma botan is described for this fungus. The teleomorph is also found on the same host in the field.     

Constant association of ophiostomatoid fungi with the bark beetle <Emphasis Type="Italic">Ips subelongatus</Emphasis> invading Japanese larch logs

Ceratocystiopsis, Ceratocystis, Grosmannia, and Ophiostoma species were isolated from Ips subelongatus and beetle-infested Japanese larch logs collected at several areas in central and northern Honshu Island, Japan, to determine constant associates of I. subelongatus. Ceratocystiopsis minuta, two species of Ceratocystis, three species of Grosmannia, and four species of Ophiostoma were isolated. Of the fungi isolated in the present study, G. laricis, O. brunneociliatum, and O. piceae were constant associates of the beetles. Ceratocystis fujiensis, Ceratocystiopsis minuta, and Ophiostoma sp. F were occasionally isolated with high frequencies of occurrence but were not consistent associates. Ceratocystis fujiensis was most often isolated as the leading fungal invasion in the sapwood of Japanese larch logs invaded by I. subelongatus, confirming that the fungus acts as a primary invader of sapwood in beetle-attacked logs. Contribution No. 221, Laboratory of Plant Parasitic Mycology, Graduate School of Life and Environmental Sciences, University of Tsukuba     

<Emphasis Type="Italic">Ambrosiella</Emphasis><Emphasis Type="Italic">beaveri,</Emphasis> sp. nov., Associated with an exotic ambrosia beetle, <Emphasis Type="Italic">Xylosandrus mutilatus</Emphasis> (Coleoptera: Curculionidae,Scolytinae), in Mississippi,USA

Xylosandrus mutilatus is an Asian ambrosia beetle that has recently established in Mississippi, Texas, Alabama, and possibly Florida, USA. We investigated the fungi associated with the mycangia (specialized fungus-transporting structures) of X. mutilatus in Mississippi. Mycangia consistently yielded an Ambrosiella sp. which was subsequently found to be closely related to, but distinct from, other Ambrosiella species affiliated with Ceratocystis. This Ambrosiella is described herein as Ambrosiella beaveri sp. nov. Also isolated were Geosmithia lavendula, G. obscura, and a yeast, Candida homelintoma. It is likely Ambrosiella beaveri was introduced along with the beetle into North America.     

Impact of the introduced yellow crazy ant Anoplolepis gracilipes on Bird Island, Seychelles

The introduced yellow crazy ant or long-legged ant Anoplolepis gracilipes was first reported in Seychelles in 1969 and now occurs on at least nine islands in the Central Seychelles. We describe the yellow crazy ant's effects on vegetation and invertebrate communities on one of these, Bird Island; in 2000, Anoplolepis (first reported in 1991) occurred there at densities at least 80 times higher than on other islands in the Central Seychelles. They were associated with high densities of coccid scale insects on foliage, especially of the native tree Pisonia grandis, in some instances causing tree death. Yellow crazy ants on Bird Island also significantly affected invertebrate communities on foliage and on the ground, both in terms of taxonomic composition and the density of specific taxa, apparently causing the local exclusion of some invertebrates.     

Parasitic microfungi of the Tatra Mountains. 3. <Emphasis Type="Italic">Spermosporina gymnadeniae</Emphasis> (Hyphomycetes): species new to Slovakia and new records from Poland

Spermosporina gymnadeniae (Hyphomycetes) on Gymnadenia sp. (Orchidaceae) collected in the Polish part of the Tatra Mts was described in 2003. The fungus was recently found at new localities in Poland and Slovakia. It was recorded on Gymnadenia conopsea s.l. and Dactylorhiza fuchsii, which are new hosts of this parasite. The fungus is described and additional illustrations are provided.     

Successful biological control of mist flower (Ageratina riparia) in New Zealand: Agent establishment, impact and benefits to the native flora

The white smut fungus (Entyloma ageratinae) and the gall fly (Procecidochares alani) were released in New Zealand in 1998 and 2001 respectively to suppress mist flower (Ageratina riparia). The fungus established and spread rapidly, crossing 80 km of sea to Great Barrier Island within 2 years. The mean number of P. alani galls increased exponentially to 1.96/stem at release sites, but dispersal was slow. The impact of the biocontrol agents was monitored once annually from 1998/99 to 2003/04, at up to 51 sites in the North Island. The mean percentage of live leaves infected with fungus rapidly reached nearly 60%. Maximum plant height declined significantly. In heavy infestations, mean percentage cover of mist flower declined from 81 to 1.5%. Galls were only recorded towards the end of the impact study, and at low mean numbers. As mist flower declined, the species richness and mean percentage cover of native plants increased. In contrast, the species richness and mean percentage cover of exotic plants (excluding mist flower) did not change significantly. Many plant species colonizing the plots were important native mid- or late-successional shrubs or trees. With few exceptions, the exotic plant species common in the plots were not weeds that appeared to threaten native forest habitats. There was only a weak “replacement weed effect” from the potentially serious invader African club moss (Selaginella kraussiana). These data, together with reports of reduced threats to rare endemic plants from mist flower, suggest this rapid, well-monitored weed biocontrol program was very successful.     

Fire ant myrmecophiles: feeding relationships ofMartinezia dutertrei andEuparia castanea (Coleoptera: Scarabaeidae) with their host ants,Solenopsis spp. (Hymenoptera: Formicidae)

Summary Feeding relationships of adultEuparia castanea Serville andMartinezia dutertrei Chalumeau with their ant hosts were studied in the laboratory using the radioactive tracer³²P.Euparia castanea was tested withSolenopsis geminata (F.),Martinezia dutertrei Chalumeau was tested withS. invicta Buren,S. richteri Forel, andS. geminata. Unlabeled beetles were exposed to various radioisotope labeled conditions for 24 hr and then checked for acquired radioactivity. In whole colony tests, both species of beetles acquired radioactivity.M. dutertrei obtained food from live ants, butE. castanea did not. Both species of beetles ate ant larvae.E. castanea also obtained food from ant larvae by strigilation. Neither species of beetle fed on ant feces or other secretions on the substrate. Both species of beetles obtained food by strigilation from fresh and decomposed worker ant cadavers.M. dutertrei also ate both kinds of ant cadavers. Both species of beetles also ate dead house flies, indicative of scavenging or feeding on ant booty.Martinezia dutertrei showed no preference for any particular ant species. Ants did not obtain food by trophallaxis or glandular secretion from either species of beetle. Martinezia dutertrei Chalumeau, 1983 (=Myrmecaphodius excavaticollis Auct.,nec Blanchard 1843).This article reports the results of research only. Mention of a proprietary product does not constitute an endorsement or a recommendation for its use by the U.S. Department of Agriculture.     

Larval Mortality Factors of <Emphasis Type="Italic">Spodoptera Littoralis</Emphasis> in the Azores

Mortality among larval developmental stages of Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae), was determined by weekly sampling on weeds in a pasture on São Miguel Island (Azores, Portugal), from August to December, over a 3-year period (1999–2001). In all the years surveyed, larvae of S. littoralis usually appeared in pastures after the third week of August, with higher abundances in September and the beginning of October. Three different factors causing larval mortality were identified: one fungal pathogen, Furia virescens (Thaxter) Humber (Zygomycetes: Entomophthoraceae), two nucleopolyhedroviruses and one larval parasitoid, Meteorus communis (Cresson) (Hymenoptera: Braconidae). The percentages of dead larvae infected by virus or fungus were significantly higher than the other causes of mortality, regardless of the year. Furthermore, the percentage of larvae that died due to virus contamination was generally higher than the percentage of larvae infected by fungus. Significant correlations between the environmental factors and the percentage of larvae infected by virus or by fungus, were only observed during 2001. In 2001, the prevalence of fungal infection was negatively correlated with that of viral infection although prevalences of these two agents were positively correlated in both 1999 and 2000. These results show that virus and fungus are potential biological control agents for S. littoralis in Azores.     

Bambusicolous fungi in Japan (8): a new species of <Emphasis Type="Italic">Pseudolachnella from</Emphasis> Yakushima Island,southern Japan

A coelomycetous fungus occurring on culms of Pleioblastus sp. in Yakushima Island, southern Japan, is described and illustrated as a new species, Pseudolachnella yakushimensis. The species is characterized by cupulate, superficial black setose conidiomata, and cylindrical 3-septate conidia with two to five appendages at each end. Pseudolachnella yakushimensis is similar to P. indica and P. scolecospora by its 3-septate conidia, but is different from them by its smaller conidia with more than two appendages.     

<Emphasis Type="Italic">Synnemapestaloides rhododendri</Emphasis>, a new genus and new species of synnematous hyphomycete,causing synnemapestaloides twig blight disease of <Emphasis Type="Italic">Rhododendron brachycarpum</Emphasis> in Japan

A hyphomycete with black synnema and appendaged phragmoconidia was collected on Rhododendron brachycarpum showing twig blight symptom in Aomori Prefecture, Japan. The twig blight is macroscopically similar to the disease symptoms caused by Pycnostysanus azaleae. The fungus, however, has determinate synnemata, (1–)3-level verticillately branched conidiophores, and Pestalotia-like conidia. It cannot be accommodated by any existing genus of anamorphic fungi. A new genus Synnemapestaloides is established to accommodate the fungus, which is named S. rhododendri. The pathogenicity of the fungus on Rhododendron leaves and shoots is confirmed by inoculation. Synnemapestaloides twig blight is proposed for the disease of R. brachycarpum caused by the fungus.     

Horizontal transmission of a microsporidium from the convergent lady beetle, Hippodamia convergens Guérin-Méneville (Coleoptera: Coccinellidae), to three coccinellid species of Nova Scotia

Convergent lady beetles, Hippodamia convergens Guérin-Méneville, are a popular choice for aphid control in North America. An unidentified microsporidium was found in H. convergens adults that were purchased from a commercial insectary in 2004. This study examined egg cannibalism and egg predation as a means of horizontal transmission of the unidentified microsporidium among H. convergens larvae and three coccinellid species found in Nova Scotia: Coccinella septempunctata (seven-spotted lady beetle), C. trifasciata perplexa (three-banded lady beetle), and Harmonia axyridis (multicolored Asian lady beetle). The microsporidium was transmitted with 100% efficiency when first instars fed on microsporidia-infected eggs. Mean spore count data from smear preparations of infected beetles suggest that the infection was as heavy in C. trifasciata perplexa (a native coccinellid) (11.2 ± 0.96 spores/100 μm²) as it was in H. convergens (the natural host) (12.8 ± 1.16) but lighter in the introduced species C. septempunctata (7.5 ± 0.65) and H. axyridis (0.8 ± 0.11). For all of the beetle species examined, larval development was significantly longer for microsporidia-infected individuals than for their uninfected cohorts. The microsporidium had no effect on larval mortality. Based on the results of this study, field-collected H. convergens should be examined for microsporidia and uninfected individuals should be used to rear individuals for release in biological control programs. However, this is unlikely to happen because H. convergens are relatively easy and inexpensive to collect from their overwintering sites for redistribution.     

Morphology and phylogeny of <Emphasis Type="Italic">Botryosphaeria dothidea</Emphasis> causing fruit rot of olives

The taxonomic position of the causal agent of fruit rot of olives was determined from fresh collections of the fungus from central Greece. In culture it formed two types of conidia, namely fusiform, hyaline, aseptate conidia typical of the genus Fusicoccum, and dark-walled, ovoid, ellipsoid or fusiform, 1–2 septate conidia that are not typically observed in Fusicoccum. A phylogenetic analysis based on ITS and EF1- sequences placed the fungus within the same clade as Fusicoccum aesculi, which is the anamorph of Botryosphaeria dothidea, and the type of the genus Fusicoccum.     

Beauveria caledonica is a naturally occurring pathogen of forest beetles

In New Zealand, two introduced scolytid beetles, Hylastes ater and Hylurgus ligniperda (Curculionidae: Scolytinae) are pests in pine plantations. Investigation of the naturally occurring pathogens of these exotic pests revealed that both are attacked by Beauveria caledonica, a species originally isolated and described from soil in Scotland. The isolates in New Zealand were identical in morphology and conserved DNA region (rDNA, elongation factor α) sequence to isolates held in the USDA-ARS insect pathogens culture collection. In bioassay, the B. caledonica isolates were highly pathogenic to adults of H. ligniperda and larvae of Tenebrio molitor. Sporulation was observed on cadavers, confirming the species can utilise the cadavers. As both species were likely to have been introduced to New Zealand from Europe, a search was made for B. caledonica in the northern UK and Ireland. The fungus was found as a naturally-occurring pathogen of the weevil pest, Hylobius abietis (Curculionidae: Scolytinae), developing in spruce and other beetles in forests in both regions.     

The effects of wilt symptom development and peroxidase induction on interactions between vascular wilt bacteria and cucumber beetles

Infection of cucumber (Cucumis sativus L.) with the bacterial pathogen Erwinia tracheiphila E. F. Smith causes vascular wilt disease in leaves, which may alter the suitability of the host plant for insects and other pathogens. In this study, densities of spotted (Diabrotica undecimpunctata howardi Barber) and striped (Acalymma vittata (Fab.) cucumber beetles (Coleoptera: Chrysomelidae) were higher on wilted leaves of mature and seedling field plants inoculated with E. tracheiphila. Bacterial infection or feeding by D. undecimpunctata howardii beetles increased total peroxidase enzyme activity in inoculated or infested leaves of greenhouse seedlings, but only beetle feeding induced higher activities in untreated systemic leaves on the same plants. Neither bacterial infection nor beetle infestation led to the development of systemic acquired resistance (SAR) to the fungal pathogen Colletotrichum orbiculare (Berk & Mont.) Arx. Susceptibility to this fungus was greater on E. tracheiphila-infected plants than on controls. The positive association between leaf wilt symptom development and beetle occurrence thus occurs in the presence of an oxidative but not anti-pathogenic response induced by both the insect and the pathogen.     

The red turpentine beetle, <Emphasis Type="Italic">Dendroctonus valens</Emphasis> LeConte (Scolytidae): an exotic invasive pest of pine in China

An exotic invasive pest of pines, the red turpentine beetle, Dendroctonus valens LeConte (Scolytidae) (RTB), was first detected in Shanxi Province, northern China, in 1998 and started causing widespread tree mortality there in 1999. This outbreak continues and has spread to three adjacent provinces, causing unprecedented tree mortality. Although it is considered a minor pest of pines in North America, RTB has proven to be an aggressive and destructive pest of Pinus tabuliformis, China’s most widely planted pine species. The bionomics and occurrence, distribution, response to host volatiles, and host preference of this pine beetle in China are compared with what is known of the beetle in its native range in North America. Factors likely contributing to D. valens success in China and control of the beetle outbreak are discussed. (−)-β-pinene was shown to be the most attractive host volatile for D. valens from the Sierra Nevada of California, whereas 3-(+)-carene is the most attractive host volatile for beetles in China. Monocultures of Pinus tabuliformis, several consecutive years of drought conditions and warm winters have apparently factored D. valens invasion and establishment in China.