Metarhizium indicum, a new species of entomopathogenic fungus infecting leafhopper, Busoniomimus manjunathi from India

Host range and virulence of Metarhizium pingshaense against Chilo species and expression of fungal virulence genes in Conogethes punctiferalis

The infectivity and virulence of Metarhizium pingshaense was tested against three major pests: Chilo infuscatellus (sugarcane early shoot borer), C. sacchariphagus indicus (sugarcane internode borer) and C. partellus (sorghum stem borer). Bioassay studies indicated high pathogenicity of this fungus against all the three species with the highest mortality recorded in C. sacchariphagus indicus (96%), followed by C. infuscatellus (93%) and C. partellus (83%). The median lethal concentrations of M. pingshaense against late-instar larvae were 4.6 × 105, 1.7 × 105, and 9.5 × 105 conidia/ml for C. infuscatellus, C. sacchariphagus indicus, and C. partellus, respectively. Median survival times ranged from 5.3 to 6.9 days for C. infuscatellus, from 5.4 to 7.9 days for C. sacchariphagus indicus, and from 6.9 to 8.3 days for C. partellus, at the tested doses of 1 × 10⁸ and 1 × 10⁷ conidia/ml. Qualitative and quantitative analyses of cuticle-degrading enzymes by the fungus, which are critical virulence factors, confirmed the production of chitinases and lipases. Enzyme production significantly increased in media with insect cuticle, indicating substrate-dependent regulation. Genes encoding chitinase and protease were cloned, sequenced, and were found to be closely related to those of M. anisopliae. RT-PCR studies confirmed the temporal expression of these two virulence genes, which play a critical role in pathogenesis. There was a gradual upregulation of these genes in the fungus during infection of its original host, Conogethes punctiferalis with the progression of time rising up to 3000-fold compared to untreated insects. These findings highlight the potential of M. pingshaense as an effective biocontrol agent for a wide range of crambid pests, supporting its development as a broad-spectrum mycoinsecticide.

The Susceptibility of Two Beauveria bassiana Strains on Rice Pests Nilaparvata lugens and Sogatella furcifera

Entomopathogenic fungi represent a valuable natural resource with significant potential as biological agents for pest management. However, different species or strains of fungi demonstrate varying effectiveness against specific targets. In this study, we assessed the impact of two fungal strains, Beauveria bassiana KN801 and KN802, on the rice planthoppers Ninaparvata lugens and Sogatella furcifera, in combination with insecticides. Our findings indicate that both B. bassiana strains can effectively infect the nymphs and adults of N. lugens and S. furcifera, resulting in a significantly higher mortality rate compared to the control groups. Notably, the B. bassiana strain KN801 demonstrated greater virulence than B. bassiana KN802 against these pests. However, no significant differences were observed when using different concentrations of the same fungal strain (B. bassiana KN801 or B. bassiana KN802) against these targets. Additionally, both fungi showed a germination rate of over 90% after treatment when combined with several common insecticides like chlorfenapyr and dinotefuran. The combined application of B. bassiana with chlorfenapyr or dinotefuran could improve pest control efficacy for these two pests. This study suggests that the two B. bassiana strains have the potential to infect rice planthoppers N. lugens and S. furcifera, indicating their promise as agents for the control of these pests.

Arboreal eurymeline leafhoppers (Hemiptera: Cicadellidae: Eurymelinae) of the Indian subcontinent with description of new genera and eight new species

Species of the arboreal leafhopper subfamily Eurymelinae formerly included in Idiocerinae (i.e., excluding Macropsini) from the Indian subcontinent are reviewed. Three tribes, Balocerini, Idiocerini and Megipocerini are represented in the subcontinent. The tribes, genera and species are diagnosed and the species are illustrated with an emphasis on the female genitalia. The species in the genus Idioscopus are revised and assigned to new genera. Species groups are recognized in the genus Idioscopus sensu stricto based on forewing venation, head sculpturing and male genitalia. The following new taxa are described and illustrated: Balocha fuscolinea sp. nov. (India: Karnataka), Bellacerus gen. nov. (type species: Idioscopus bellus Viraktamath), Busonia distanti sp. nov. (Nepal; India: Meghalaya), B. manipurensis sp. nov. (India: Manipur), Jogina gen. nov. (type species: Idioscopus robustipennis Viraktamth), Keralus gen. nov. (type species: Idioscopus webbi Viraktamath), Matangia gen. nov. (type species: Idioscopus capriliana Viraktamath & Murphy), M. kodaiensis sp. nov. (India: Tamil Nadu), Metidiocerus gnezdilovi sp. nov. (India: Jammu & Kashmir), Ulavius gen. nov. (type species: Idioscopus anasuyae Viraktamath & Viraktamath), U. parvathiae sp. nov. (India: Karnataka), U. poornachandrai sp. nov. (India: Karnataka) and U. radhamaniae sp. nov. (India: Karnataka). The genus Metidocerus Ossiannilsson is recorded for the first time from the subcontinent. Busonia amentata Distant is redescribed based on one male paratype from Myitta (Myanmar) and it is shown that the specimen identified as this species by Maldonado-Capriles (1977) is in error. Idiocerus quinquepunctatus Melichar 1903 earlier considered as a junior synonym of I. atkinsoni Lethierry 1889, is resurrected from synonymy and Amritodus brevistylus Viraktamath 1976 syn. nov. is treated as a junior synonym of I. quinquepunctatus. Idioscopus scutellatus (Distant 1908) syn. nov. is considered as a junior synonym of I. clypealis (Lethierry 1898). Balocha anufrievi Kameswara Rao & Ramakrishnan 1979 syn. nov., B. bifurcata Kamswara Rao, Ramakrishanan & Ghai 1979 syn. nov. and B. maldonadoi Kamswara Rao & Ramakrishan 1979 syn. nov. are treated as junior synonms of the wide-spread B. astuta (Melichar 1903) described from Sri Lanka. The following new combinations are proposed: Amritodus quinquepunctataus (Melichar) comb. nov., Bellacerus bellus (Viraktamath) comb. nov., Jogina robustipennis (Viraktamath) comb. nov., Keralus webbi (Viraktamath) comb. nov., Matangia capriliana (Viraktamath & Murphy) comb. nov., M. indica (Viraktamath) comb. nov., M. thapai (Viraktamath & Hongsaprug) comb. nov., Metidiocerus deodarae (Viraktamath & Sohi) comb. nov., Ulavius anasuyae (Viraktamath & Viraktamath) comb. nov. U. decoratus (Viraktamath) comb. nov., U. dworakowskae (Viraktamath) comb. nov., U. jayashriae (Viraktamath & Viraktamath) comb. nov. and U. spectabilis (Viraktamath) comb. nov. These species were placed earlier in the genus Idioscopus except Metidiocerus deodarae which was in the genus Idiocerus. Keys to subtribes, genera and species under each genus are also given. Busonia manipurensis sp. nov. and Busoniomimus manjunathi are actively attended by ants (Hymenoptera: Formicidae).

Zinc solubilization and organic acid production by the entomopathogenic fungus, Metarhizium pingshaense sheds light on its key ecological role in the environment

We report for the first-time higher zinc (Zn) solubilization efficiency and plant growth promotion by an entomopathogenic fungus (EPF), Metarhizium pingshaense IISR-EPF-14, which was earlier isolated from Conogethes punctiferalis, a pest of global importance. The Zn solubilizing efficiency of the fungus varied depending on the type of insoluble source of Zn used, which was observed to be 1.6 times higher in Zn3(PO4)2-amended media compared to ZnO media. In liquid media, there was a 6.2-fold increase in available Zn in ZnO-amended media, whereas a 20.2-fold increase in available Zn was recorded in Zn3(PO4)2 medium. We ascribe the production of various organic acids such as gluconic, keto-gluconic, oxalic, tartaric, malonic, succinic and formic acids, which in general, interact with insoluble Zn sources and make them soluble by forming metal cations and displacing anions as the major mechanism for Zn solubilization by M. pingshaense. However, the type and amount of organic acid produced in the media varied depending on the source of Zn used and the incubation period. Application of the fungus alone and in combination with insoluble Zn sources enhanced various plant growth parameters in rice and cardamom plants. Moreover, the uptake of Zn in rice plants was enhanced up to ~2.5-fold by fungal application. The fungus also exhibited various other plant growth-promoting traits, such as production of Indole-3-acetic acid, ammonia, siderophores, solubilization of mineral phosphate, and production of hydrolytic enzymes such as α-amylase, protease, and pectinase. Hence, apart from its use as a biological control agent, M. pingshaense has the potential to be used as a bio-fortifier to enhance the solubilization and uptake of Zn from nutrient poor soils under field conditions. Our findings shed light on the broader ecological role played by this fungus and widen its scope for utilization in sustainable agriculture.