Histopathological Alterations in Nilaparvata lugens (Hemiptera: Delphacidae) after Exposure to Cordyceps javanica.

The brown planthopper (BPH), Nilaparvata lugens (Stål, 1854), is a pest of rice plants worldwide. Cordyceps javanica is a destructive entomopathogenic fungus known to attack leafhoppers or BPHs specifically. Live adult BPH samples were inoculated with isolated C. javanica PSUC002, and their interaction was morpho-histologically examined from 0 to 120 h post-inoculation (pi). We observed that the mortality of BPH continuously increased until 120 h pi (Day 5). Tissue alterations in the host were examined after infection using morphological and histological methods, including the Grocott Methenamine Silver stain test (GMS). Filamentous fungi were first found on the external integument at 12 h pi, and fungal conidia attached to the integument at 24 h pi. However, the initial degeneration of BPHs was identified by histology at 6 h pi especially in the integument and adipose tissue. We identified the degeneration and loss of integument and adipose tissue of infected BPHs at 12 h pi, and their necrosis was completed at 96 h pi. The enzymatic index of the sampled fungi (chitinase and protease) peaked at 7 days of incubation. This study demonstrated that C. javanica PSUC002 is useful to control the BPHs as an eco-friendly practice and will possibly be applied in agriculture.

Comprehensive Structure of the Female Marine Water-Strider Asclepios annandalei Distant, 1915 from Pranburi River Estuary, Thailand: New Information for the Genus Asclepios.

The objective of this study was to describe the structure and histochemistry of the systemic organs in the female marine water-strider Asclepios annandalei from Pranburi river estuary, Thailand. Results from this study revealed for the first time that the integumentary system of this species consisted of three layers including epicuticle, exocuticle and endocuticle. The muscular system apparently contained only skeletal muscle along the body. In the urinary system, we observed well-developed Malpighian tubules, each of which was covered with the simple cuboidal epitheliums. These epitheliums also contained the secretory granules that were reacted positively with periodic acid Schiff (PAS). The digestive system of this species was composed of three distinct parts including foregut, midgut and hindgut. The respiratory system was composed of the respiratory organ, which was rarely found near the integument system. This organ was lined with a simple squamous epithelium. Two regions of nervous system, i.e., frontal ganglion connected to the eye structure and ventral nerve cord, were found. Each ganglion basically consisted of two layers, outer cortex and inner medullae. The outer cortex contained three types of cells, including neurosecretory cells, neuroglial cells and neurons. The cytoplasmic inclusion of neurosecretory cells contained secretory granules, which reacted positively with PAS, indicating the presence the glycoprotein. The neuroglia and neuron were also observed in the inner medullae layer. The female reproductive system (the ovarian structure, the reproductive tract and the accessory organ) of this gerrid species was seen under histological sections. The well-developed integument system and Malpighian tubule as well as the abundant respiratory organ is a characteristic of this species, which might be useful for the adaption to the estuarine condition.

Morphological and Molecular Characterization of Calonectria foliicola Associated with Leaf Blight on Rubber Tree (Hevea brasiliensis) in Thailand.

Leaf blight is commonly observed in rubber trees (Hevea brasiliensis) and can be caused by several fungal species. From October to December 2021, the emergence rubber tree disease was observed in Krabi province, southern Thailand. Small brown to dark brown spots developed on the leaves of rubber trees and later expanded into most parts of the leaves. Fungal isolates were isolated from infected tissues and a total of 15 Calonectria-like isolates were recovered from 10 infected leaf samples. Pathogenicity testing using the agar plug method revealed that four isolates caused leaf blight on rubber tree, similar to the situation in natural infections. Based on morphological study and the molecular properties of internal transcribed spacer (ITS), calmodulin (cal), translation elongation factor 1-α (tef1-α), and ß-tubulin 2 (tub2) sequences, the four fungal isolates were identified as Calonectria foliicola. To the best of our knowledge, this is the first report of rubber trees pas a new host for C. foliicola in Thailand and elsewhere. This study reports on an emerging disease affecting rubber trees in Thailand, and the results are of benefit for the development of an appropriate method to manage this emerging disease in Thailand.

Entomopathogenic Fungi Biodiversity in the Soil of Three Provinces Located in Southwest China and First Approach to Evaluate Their Biocontrol Potential.

Entomopathogenic fungi (EF), who represent active agents to control insect natural populations, usually persist in terrestrial habitats. Southwest area in China has various climate conditions and abundant plant biodiversity (crop, forest, grassy, orchard and arable areas). Nevertheless, the potential of soil-inhabitant EF as insect pest biocontrol agents, is unknown. In this study, first the EF biodiversity from soil of three provinces (Guizhou, Sichuan, and Yunnan) was surveyed. Then, the virulence of 29 isolated strains against Bemesia tabaci and Spodoptera litura was assessed. After analyzing 212 soil samples, 497 isolated fungi were identified. Out of them, 490 isolates were classified in 45 species of 24 genera, whereas the other seven isolates, belonging to Paecilomyces and Purpureocillium genera, were not identified under species level. Furthermore, the EF biodiversity from soil of Sichuan, Yunan, and Guizhou areas, analyzed by Shannon Wiener Index (SWI) was rated at 2.98, 1.89, and 2.14, while SWIs-biodiversity in crop, forest, grassy, orchard and arable areas was rated at 2.88, 2.74, 3.05, 2.39, and 2.47. SWI data suggested that soil from Sichuan area and grassy had higher EF biodiversity compared with other analyzed provinces and areas. Virulence bioassay results indicated that, out of the 29 isolates tested, 24 were pathogenic against B. tabaci and S. litura, resulting in mortality rates >10%. In conclusion, this study reports the EF distribution and biodiversity in soil from three provinces located at Southwest China, whereas their potential use as a tool for the B. tabaci and S. litura biocontrol must be further investigated.

Volatile Organic Compound from Trichoderma asperelloides TSU1: Impact on Plant Pathogenic Fungi.

Soil microorganisms are well studied for their beneficial effects on plant growth and their impact on biocontrol agents. The production of volatile antifungal compounds emitted from soil fungi is considered to be an effective ability that can be applied in biofumigants in the control of plant diseases. A soil fungus, Trichoderma asperelloides TSU1, was isolated from flamingo flower cultivated soil and identified on the basis of the morphology and molecular analysis of the internal transcribed spacer (ITS), rpb2, and tef1-α genes. To test T. asperelloides TSU1-produced volatile organic compounds (VOCs) with antifungal activity, the sealed plate method was used. The VOCs of T. asperelloides TSU1 inhibited the mycelial growth of fungal pathogens that were recently reported as emerging diseases in Thailand, namely, Corynespora cassiicola, Fusarium incarnatum, Neopestalotiopsis clavispora, N. cubana, and Sclerotium rolfsii, with a percentage inhibition range of 38.88-68.33%. Solid-phase microextraction (SPME) was applied to trap VOCs from T. asperelloides TSU1 and tentatively identify them through gas chromatography-mass spectrometry (GC/MS). A total of 17 compounds were detected in the VOCs of T. asperelloides TSU1, and the dominant compounds were identified as fluoro(trinitro)methane (18.192% peak area) and 2-phenylethanol (9.803% peak area). Interestingly, the commercial 2-phenyethanol showed antifungal activity against fungal pathogens that were similar to the VOCs of T. asperelloides TSU1 by bioassay. On the basis of our study's results, T. asperelloides TSU1 isolated from soil displayed antifungal abilities via the production of VOCs responsible for restricting pathogen growth.

Revision of the xyleborine ambrosia beetle genus Microperus Wood, 1980 (Curculionidae, Scolytinae, Xyleborini) of Thailand with four new species and four newly recorded species.

Microperus Wood, 1980 ambrosia beetles in Thailand are reviewed. Four species, M.bidentatus sp. nov., M.bucolicus sp. nov., M.globodeclivis sp. nov., and M.serratus sp. nov. are described. Four new combinations are given: Microperusarmaticeps (Schedl, 1942) comb. nov., Microperusexsculptus (Eggers, 1927) comb. nov., Microperuspedellus (Schedl, 1969) comb. nov., and Microperusspicatulus (Browne, 1986) comb. nov., stat. res., all from Xyleborus. Two new synonyms are proposed: Microperuscruralis (Schedl, 1975) (= Xyleborusmyllus Browne, 1986 syn. nov.), Microperusexsculptus (Eggers, 1927) (= Xyleborusdentipennis Browne, 1983 syn. nov.). Four species are reported from Thailand for the first time: Microperuschrysophylli (Eggers, 1930), Microperusexsculptus, Microperusnanus (Browne, 1949) and Microperusquercicola (Eggers, 1926). With the inclusion of the Microperus species described and recorded herein, the diversity of Microperus is increased to 35 species, of which 18 are recorded in Thailand. An updated key to the Microperus of the Indochinese Peninsula and China is provided. The taxonomy, diagnostic characters, and distribution of species are briefly discussed.

Diversity of Linear Non-Ribosomal Peptide in Biocontrol Fungi.

Biocontrol fungi (BFs) play a key role in regulation of pest populations. BFs produce multiple non-ribosomal peptides (NRPs) and other secondary metabolites that interact with pests, plants and microorganisms. NRPs-including linear and cyclic peptides (L-NRPs and C-NRPs)-are small peptides frequently containing special amino acids and other organic acids. They are biosynthesized in fungi through non-ribosomal peptide synthases (NRPSs). Compared with C-NRPs, L-NRPs have simpler structures, with only a linear chain and biosynthesis without cyclization. BFs mainly include entomopathogenic and mycoparasitic fungi, that are used to control insect pests and phytopathogens in fields, respectively. NRPs play an important role of in the interactions of BFs with insects or phytopathogens. On the other hand, the residues of NRPs may contaminate food through BFs activities in the environment. In recent decades, C-NRPs in BFs have been thoroughly reviewed. However, L-NRPs are rarely investigated. In order to better understand the species and potential problems of L-NRPs in BFs, this review lists the L-NRPs from entomopathogenic and mycoparasitic fungi, summarizes their sources, structures, activities and biosynthesis, and details risks and utilization prospects.

Genome Sequence Resource of 'Candidatus Liberibacter asiaticus' from Thailand.

'Candidatus Liberibacter asiaticus' (Las) is an unculturable α-proteobacterium associated with citrus huanglongbing (HLB), a devastating disease currently threatening the citrus industry worldwide. Here, we present the genome sequence of Las strain TaiYZ2 from an HLB-affected pomelo tree in Hat Yai district, Songkhla Province, Thailand. The TaiYZ2 genome is composed of 1,230,623 bp with G+C content of 36.4%. This is the first Las genome sequence from Thailand, which will enrich current Las genome resource and facilitate HLB research and management.

New species of Myrmosinae (Hymenoptera: Mutillidae) from Southeastern Asia.

The subfamily Myrmosinae is generally Holarctic in distribution with five species known from the Oriental Region. Three species, Kudakrumia malaenglek sp. nov., Kudakrumia loaibonho sp. nov., and Krombeinella brothersi sp. nov., were recently discovered from Thailand and Vietnam, representing the new Southeasternmost distribution records for this subfamily. Keys to Old World genera of Myrmosinae and to males of Kudakrumia and Krombeinella are also provided. The genus Krombeinella Pate is newly recorded from the Oriental region.

The female velvet ants (aka modkhong) of southern Thailand (Hymenoptera: Mutillidae), with a key to the genera of southeast Asia.

A review of female mutillids in southern Thailand is presented, based on literature, loaned material, and two field expeditions. Thirty-three species in 23 genera have been previously recorded from Thailand (Lelej 2005; Lelej et al. 2016, 2017; Okayasu et al. 2018). In March and April 2017, 337 female specimens were collected in the provinces of Krabi, Nakhon Si Thammarat, Phatthalung, Songkhla, and Trang. In May 2018, 255 female specimens were collected in the provinces of Kanchanaburi, Phetchaburi, and Surat Thani. These collected specimens were sorted into 38 morphospecies: 13 already known from Thailand, nine previously described species newly recorded from Thailand, and 16 new to science and described here. Based on loaned material, three more described species were newly recorded from southern Thailand and one more undescribed species was found. Keys to females of the 31 mutillid genera found in southeast Asia and 42 mutillid species studied from southern Thailand are provided. Illustrations and diagnoses are provided for each species studied in southern Thailand, including the following 17 new species: Bischoffitilla tokay Williams, Bischoffitilla cambrai Williams, Mickelomyrme puttasoki Williams, Mickelomyrme kinguri Williams, Nordeniella maleeae Williams, Smicromyrme helarctos Williams, Smicromyrme borkenti Williams, Smicromyrme thaochani Williams, Krombeinidia agricola Williams, Krombeinidia chang Williams, Krombeinidia baanmaka Williams, Orientidia manleyi Williams, Orientidia thoawanae Williams, Petersenidia modkhong Williams, Petersenidia leleji Williams, Trogaspidia pittsi Williams, and Trogaspidia wilsoni Williams. Three new synonyms and one new combination are recognized: Bischoffitilla lamellata (Mickel, 1933) = Squamulotilla arundinacea Pagden, 1934, syn. nov., Mickelomyrme pusillaeformis (Hammer, 1962), comb. nov. = Mickelomyrme yunnanensis Lelej, 1996, syn. nov., Trogaspidia pagdeni (Mickel, 1933) = Timulla (Trogaspidia) pagdeni nodoa Mickel, 1933, syn. nov. Finally, two other taxa are raised to full species from subspecies status, Eotrogaspidia oryzae (Pagden, 1934), status resurr., and Trogaspidia lingnani (Mickel, 1933), status nov. New combination is also proposed for Krombeinidia meeungensis (Cockerell, 1928), comb. nov. Twenty-three new country records are presented: 12 from Thailand, four from Vietnam, four from Laos, two from Cambodia, and one from Indonesia.

Effect of temperature on the development and survival of immature stages of the carambola fruit fly, Bactrocera carambolae, and the Asian papaya fruit fly, Bactrocera papayae, reared on guava diet.

Members of the Bactrocera dorsalis Hendel (Diptera: Tephritidae) complex constitute well-recognized destructive pests of fruits in peninsular Thailand. The development and survival of immature stages of the carambola fruit fly, Bactrocera carambolae Drew & Hancock, and the Asian papaya fruit fly, Bactrocera papayae Drew & Hancock, were compared at six constant temperatures of 15, 20, 25, 27, 30, and 35°C, 70 ± 5% relative humidity, and a photoperiod of 12:12 (L:D). The objectives were to determine the effect of temperature on the developmental stages for optimizing rearing and to understand the geographical pattern of occurrence of these fruit fly species. A strong and positive linear relationship was observed between temperature and developmental rate of immature stages of B. carambolae. Similarly, a strong and positive linear relationship was observed between temperature and developmental rate of B. papayae. A temperature summation model was used to estimate the lower threshold temperature and the thermal constant. Bactrocera papayae was significantly faster in development and higher in survival and appeared to be better adapted to low temperatures than B. carambolae, as it exhibited the lowest threshold temperatures at all immature stages. The observed differences in response to various temperatures revealed to some extent the impact of temperature on these species' distribution in peninsular Thailand and other parts of the world.