Conidiobolus lunulus, a new entomophthoralean species isolated from leafcutter ants.

Entomophthoralean fungi with pathogenic abilities to infect social insects are rare. Here, we describe a fungus isolated from leafcutter ants. Morphologically, the fungus has spherical primary conidia and two types of microconidia: one with the same shape as the primary conidia and another with an elliptical to half-moon shape. The fungus also produces villose conidia known previously only from Conidiobolus coronatus. A multilocus phylogenetic analysis was performed with nuc rDNA sequences from three regions (28S, 18S, and internal transcribed spacer [ITS]). Our isolates are distinguished as a new species, described here as Conidiobolus lunulus, and is more closely related to C. brefeldianus than to C. coronatus, despite the greater morphological resemblance to the latter. Morphological differences, unique phylogenetic placement, and isolation from an altogether new host support this finding. This is the first record of an entomophthoralean species isolated from leafcutter ants.

Leptolegnia chapmanii (Straminipila: Peronosporomycetes) as a future biorational tool for the control of Aedes aegypti (L.).

The aim of the present review is to summarize the current knowledge about Leptolegnia chapmanii as a pathogen of mosquito larvae. To this end, we present data on its identification, distribution, host range and effects on non-target organisms, effects of environmental factors, in vitro growth, release and persistence in anthropic environments, and effect combined with other insecticides. The data presented allow confirming its potential as a biocontrol agent.

UV-B radiation reduces in vitro germination of Metarhizium anisopliae s.l. but does not affect virulence in fungus-treated Aedes aegypti adults and development on dead mosquitoes.

AIMS: Control of diurnal Aedes aegypti with mycoinsecticides should consider the exposure of fungus-treated adults to sunlight, and especially to UV-B radiation that might affect activity of conidia applied on the mosquito's surface. METHODS AND RESULTS: Germination of Metarhizium anisopliae s.l. IP 46 conidia on SDAY medium was not affected at the lowest level of radiation with UV-B, 0·69 kJ m-2 , but was retarded and reduced at higher 2·075 and 4·15 kJ m-2 , and completely inhibited at ≥8·3 kJ m-2 . In contrast, germination of conidia applied onto fibreglass nettings and exposed from 0 to 16·6 kJ m-2 did not differ significantly among levels of irradiance exposure and the controls. There was also no significant impact of UV-B up to 16·6 kJ m-2 on the adulticidal activity of IP 46 and on the subsequent conidiogenesis on cadavers. The Quaite-weighted UV-B irradiance in the laboratory (1152 mW m-2 ) was higher than the natural sunlight irradiance observed in the city of Goiânia in Central Brazil on midday (706 mW m-2 in August to 911 mW m-2 in October 2015). CONCLUSIONS: UV-B does not impair the activity of IP 46 conidia applied previously to radiation on A. aegypti adults. SIGNIFICANCE AND IMPACT OF THE STUDY: Findings contribute to a better understanding of the effectiveness of M. anisopliae against day-active A. aegypti and its potential for biological mosquito control.

New insights into the infection of the American cockroach Periplaneta americana nymphs with Metarhizium anisopliae s.l. (Ascomycota: Hypocreales).

AIMS: To study the marked resistance of Periplaneta americana to entomopathogenic Metarhizium anisopliae. METHODS AND RESULTS: The low susceptibility of 4th instar nymphs applied topically with conidia seemed to be related to an active removal of conidia by the cockroach and to a disabled or retarded germination and subsequent development of conidia on the cuticle (up to 80% germination in the next 7 days after application). Inhibitions or delays of germination were related to the composition of the epicuticular fatty acids (30·1% w/w oleic, 28·3% w/w linoleic, 24·5% w/w palmitic and 11·7% w/w stearic acid) reported here. Propagules invading the nymphs through the cuticle took at least 3 days to reach the haemocoel, and no propagules were found after day 8 post-treatment. Strain IP 46 infected >50% of nymphs treated with doses ≥2 × 104  hyphal bodies (HB) nymph-1 and reduced the survival of nymphs ≤50%. Most nymphs (>70%) survived after injection of 6 × 103 and 2 × 103  HB nymph-1 . CONCLUSIONS: Findings emphasize a distinct resistance of nymphs of the American cockroach to infections by M. anisopliae. SIGNIFICANCE AND IMPACT OF THE STUDY: Our findings provide support for the development of biological control of this synanthropic cockroach pest.

Susceptibility of adults of the cerambycid beetle Hedypathes betulinus to the entomopathogenic fungi Beauveria bassiana, Metarhizium anisopliae, and Purpureocillium lilacinum.

The cerambycid beetle Hedypathes betulinus (Klug) (Coleoptera: Cerambycidae) causes severe damage to yerba mate plants (Ilex paraguariensis (St. Hilaire) (Aquifoliales: Aquifoliaceae)), which results in large losses of production. In this study, the pathogenicity of entomopathogenic fungi of the species Beauveria bassiana (Balsamo-Crivelli) Vuillemin (Hypocreales: Cordycipitaceae), Metarhizium anisopliae sensu lato (Metschnikoff) Sorokin (Hypocreales: Clavicipitaceae), and Purpureocillium lilacinum (Thom) Luangsa-ard, Hywel-Jones, Houbraken and Samson (Hypocreales: Ophiocordycipitaceae) on yerba mate were evaluated. Fifteen isolates of B. bassiana, two of M. anisopliae, and seven of P. lilacinum on H. betulinus adults were analyzed under laboratory conditions. The raw mortality rate caused by B. bassiana isolates varied from 51.1 to 86.3%, and their LT50 values varied between 8.7 and 13.6 d. The isolates of M. anisopliae caused 69.6‒81.8% mortality, and their LT50 values varied between 7.4 and 7.9 d. In contrast, isolates of P. lilacinum were not pathogenic. M. anisopliae and B. bassiana isolates were pathogenic against H. betulinus adults, suggesting that they may be useful in biological control programs for insect pests of yerba mate.

Prevalence of entomophthoralean fungi (Entomophthoromycota) of aphids (Hemiptera: Aphididae) on solanaceous crops in Argentina.

Solanum melongena L. and Capsicum annuum L. were sampled in Argentina to determine the prevalence of fungal diseased aphids. The pathogens identified were Pandora neoaphidis (Remaudière & Hennebert) Humber and Zoophthora radicans (Brefeld) Batko (Entomophthorales: Entomophthoraceae) on aphids from eggplants; and P. neoaphidis and Entomophthora planchoniana Cornu (Entomophthorales: Entomophthoraceae) on aphids from peppers. The highest fungal prevalence was 45.5% (n=2296) and 98.1% (n=3212) from aphids on eggplants and peppers, respectively. In both crops, significant differences were found on number of infected aphids among developmental stages. P.neoaphidis and E. planchoniana caused epizootics in M. persicae.

Histopathology caused by the entomopathogenic fungi, Beauveria bassiana and Metarhizium anisopliae, in the adult planthopper, Peregrinus maidis, a maize virus vector.

The planthopper Peregrinus maidis (Ashmead) (Hemiptera: Delphacidae) is an important vector of maize viruses in tropical and subtropical areas. Planthoppers are biologically controlled with several species of entomopathogenic fungi that have been isolated from these insect pests of rice in Asia. Beauveria bassiana (Balsamo-Crivelli) Vuillemin and Metarhizium anisopliae (Metschnikoff) Sorokin (Hypocreales: Clavicipitaceae) appear to be the most useful against planthoppers because of their ease of mass production, storage, virulence, and application. In the present study, adults of P. maidis infected with B. bassiana and M. anisopliae were observed under light and scanning electron microscopy to characterize morphologically the process of infection and the development of these fungi, prior to and after the death of the host. The hydrophobic conidia of both fungal species were able to attach to all body regions, with a preference for surfaces containing hairs. Few germinated conidia were observed on the insect's body surface at 24, 48, and 72 hr post-inoculation. On the cuticular surface of P. maidis treated with B. bassiana and M. anisopliae, bacillus-like bacteria were observed. These microorganisms could be interacting with fungal conidia, playing a role of antibiosis that will not allow the fungal pathogens to germinate and penetrate. In the colonization events observed in this study, the formation and multiplication of hyphal bodies by both fungal species inside the host's body was noted. The host's whole body was invaded by hyphae between five and six days post-inoculation, and body fat was the most affected tissue.

Effects of temperature, pH and salinity on the infection of Leptolegnia chapmanii Seymour (Peronosporomycetes) in mosquito larvae.

The effects of temperature, pH, and NaCl concentrations on the infectivity of zoospores of Leptolegnia chapmanii (Argentine isolate) were determined for Aedes aegypti and Culex pipiens under laboratory conditions. Zoospores of L. chapmanii were infectious at temperatures between 10 and 35 degrees C but not at 5 or 40 degrees C. At the permissive temperatures, mortality rates in young instars were much higher than in older instars and larvae of Ae. aegypti were more susceptible to L. chapmanii than larvae of Cx. pipiens. At 25 degrees C, Ae. aegypti larvae challenged with L. chapmanii zoospores resulted in 100% infection at pH levels ranging from 4 to 10. Larvae of Cx. pipiens exposed to similar pH and zoospore concentrations resulted in increasing mortality rates from 62% to 99% at pH 4 to 7, respectively, and then decreased to 71% at pH 10. Aedes aegypti larvae exposed to L. chapmanii zoospores in NaCl concentrations ranging from 0 to 7 parts per thousand (ppt) at 25 degrees C resulted in 100% mortality while mortality rates for Cx. pipiens decreases from 96% in distilled water to 31.5% in water with 6 ppt NaCl. Control Cx. pipiens larvae died when exposed at a NaCl concentration of 7 ppt. Vegetative growth of L. chapmanii was negatively affected by NaCl concentrations. These results have demonstrated that the Argentinean isolate of L. chapmanii tolerated a wide range of temperatures, pH, and salinity, suggesting that it has the potential to adapt to a wide variety of mosquito habitats.

Hongos patógenos de insectos en Argentina (Zygomycetes: Entomophthorales) / Pathogenic fungi of insects from Argentina (Zygomycetes: Entomophthorales)

Three species of Entomophthorales entomopathogenic fungi (Zygomycotina: Zygomycetes) have been identified from insects in agricultural crops (Buenos Aires Province, Argentina): Zoophthora radicans Batko (Brefeld); Entomophthora planchoniana Cornu and Pandora gammae (Weiser) Humber. Fungal structure measurements are reported.

Se informa de tres especies de hongos Entomophthorales en insectos encontrados en cultivos agrícolas en la Provincia de Buenos Aires, Argentina: Zoophthora radicans Batko (Brefeld); Entomophthora planchoniana Cornu y Pandora gammae (Weiser) Humber. Se incluyen las medidas de las estructuras fúngicas.

[Pathogenic fungi of insects from Argentina (Zygomycetes: Entomophthorales)]. / Hongos patógenos de insectos en Argentina (Zygomycetes: Entomophthorales).

Pathogenic fungi of insects from Argentina (Zygomycetes: Entomophthorales). Three species of Entomophthorales entomopathogenic fungi (Zygomycotina: Zygomycetes) have been identified from insects in agricultural crops (Buenos Aires Province, Argentina): Zoophthora radicans Batko (Brefeld); Entomophthora planchoniana Cornu and Pandora gammae (Weiser) Humber. Fungal structure measurements are reported.

Evaluation of histological techniques for the detection of fungal infections caused by Leptolegnia chapmanii (Oomycetes: Saprolegniales) in Aedes aegypti (Diptera: Culicidae) larvae.

We evaluated which of the fixatives and stains most frequently used for observation of insect tissues were the most appropriate for histopathological visualization of entomopathogenic fungal infections with Leptolegnia chapmanii in larvae of Aedes aegypti. The best contrast between the host tissues and the fungal structures was obtained when using a combination of Camoy fixative with Grocott staining contrasted with light green. Masson trichromic stain combined with 10% formaldehyde-phosphate buffer also provided satisfactory results--a good contrast and clearly distinguishable host tissues and fungal structures.

Host range and specificity of an Argentinean isolate of the aquatic fungus Leptolegnia chapmanii (Oomycetes: Saprolegniales), a pathogen of mosquito larvae (Diptera: Culicidae).

An isolate from Argentina of the fungal mosquito pathogen Leptolegnia chapmanii (ARSEF 5499), was tested against 12 species of mosquito larvae and on species of non-target aquatic invertebrates and vertebrates. The mosquito species tested were Aedes aegypti, Anopheles sp., Culex apicinus, Cx. castroi, Cx. dolosus, Cx. pipiens, Cx. renatoi, Isostomyia paranensis, Ochlerotatus albifasciatus, Oc. crinifer, Psorophora cyanescens, and P. ferox. Mosquito larvae of 10 species were susceptible, with mortality rates from 10-100%. Two mosquito species Cx. renatoi and I. paranensis were not infected by Leptolegnia. None of the non-target fauna treated was infected by L. chapmanii with exception of members of the Family Chironomidae which were susceptible at low infection rates.

Survival and differential development of Entomophaga maimaiga and Entomophaga aulicae (Zygomycetes: Entomophthorales) in Lymantria dispar hemolymph.

The closely related entomophthoralean fungi Entomophaga aulicae and E. maimaiga are both host-specific pathogens of lepidopteran larvae. However, these fungi do not have the same host range. The first objective of this study was to compare the fate of E. aulicae in the nonpermissive host Lymantria dispar with the fate of the successful pathogen E. maimaiga over the same time period. In the hemolymph of L. dispar injected with E. maimaiga protoplasts, the number of hemocytes demonstrated a decreasing trend after the first day postinjection and hemocytes completely disappeared by day 5, with the majority of larvae dying in 5.6 +/- 0.1 days. In L. dispar larvae, E. maimaiga infections developed successfully, evidenced by increasing numbers of protoplasts and hyphal bodies prior to host mortality. In contrast, at day 5 hemocytes were readily visible in hemolymph of E. aulicae-injected larvae, but E. aulicae cells did not increase in numbers, although persisting in the hemolymph for at least 16 days postinjection. For both fungal species, when hemolymph samples from injected insects were introduced to culture media viable fungal cultures were always produced. Both E. aulicae and E. maimaiga occurred in hemolymph initially after injection as protoplasts. For E. maimaiga, after day 3, <50% of fungal cells were hyphal bodies until insect death when most cells regenerated cell walls. For E. aulicae, from day 2 equal numbers of fungal cells in the hemolymph occurred as protoplasts and hyphal bodies. To investigate the cause of fungistasis in E. aulicae-injected larvae, E. aulicae cell cultures exposed to partially purified protein fractions from hemolymph of larvae infected with either fungus displayed increased lysis and decreased viability at lower concentrations of protein fractions compared with E. maimaiga cell cultures. These studies demonstrate that E. aulicae does not increase in L. dispar hemolymph, although it persists and results suggest that proteinaceous factors induced within the hemolymph may limit the capacity of E. aulicae to develop successful infections.

[Southernmost record of the fungus Leptolegnia chapmanii (Oomycetes: Saprolegniales) as a mosquito larvae pathogen (Diptera: Culicidae).]. / Registro más austral del hongo Leptolegnia chapmanii (Oomycetes: Saprolegniales) como patógeno de larvas de mosquitos (Diptera: Culicidae).

In the present paper we communicate the southernmost record and the first for the neotropical region of the fungus Leptolegnia chapmanii (Oomycetes: Saprolegniales) as a mosquito larvae pathogen, in Buenos Aires, Argentina. The fungal description is extended as the host range and geographic distribution.

[Presence of the fungus Coelomomyces iliensis var. indus (Chytridiomycetes: Blastocladiales) as pathogen of mosquito larvae (Diptera: Culicidae) in Argentina]. / Presencia del hongo Coelomomyces iliensis var. indus (Chytridiomycetes: Blastocladiales) como patógeno de larvas de mosquitos (Diptera: Culicidae) en la República Argentina.

In the present paper we report the presence of the fungus Coelomomyces iliensis var. indus as a larval pathogen of Culex dolosus Lynch Arribalzaga 1891 (Diptera: Culicidae), in Punta Lara, Buenos Aires, Argentina. The fungal description is extended as the host range and the geographic distribution.