Dirty panicle disease in coconuts (Cocos nucifera) was first observed in the KU-BEDO Coconut BioBank, Nakhon Pathom province, Thailand. The occurrence of the disease covers more than 30% of the total coconut plantation area. The symptoms include small brown to dark brown spots and discoloration of male flowers. Herein, three fungal strains were isolated from infected samples. Based on the morphological characteristics the fungal isolates, they were classified into two genera, namely, Alternaria (Al01) and Fusarium (FUO01 and FUP01). DNA sequences of internal transcribed spacer (ITS), glyceraldehyde 3-phosphate dehydrogenase (GAPDH), translation elongation factor 1-α (tef1-α), and RNA polymerase II second largest subunit (rpb2) revealed Al01 as Alternaria burnsii, whereas DNA sequences of ITS, rpb2, and tef1-α identified FUO01 and FUP01 as Fusarium clavum and F. tricinctum, respectively. A pathogenicity test by the agar plug method demonstrated that these pathogens cause dirty panicle disease similar to that observed in natural infections. To the best of our knowledge, this is the first report on the novel dirty panicle disease in coconuts in Thailand or elsewhere, demonstrating that it is associated with the plant pathogenic fungi A. burnsii, F. clavum, and F. tricinctum.

Plant trichomes generally act as a physical defense against herbivore attacks and are present in a variety of plants, including rice plants. This research examined the physical and chemical defenses of rice plants against the brown planthopper (BPH), Nilaparvata lugens (Stål) (Hemiptera: Delphacidae). A total of 10 rice varieties were used in this study. An electron microscope was used to observe trichomes. Constitutive and induced volatile compound profiles were assessed using GC-MS analyses. The preference of BPH for volatiles from the 10 rice plants was tested using a two-choice arena olfactometer system. The density of prickle trichomes had a negative relationship with the BPH injury level. Without BPH infestation, the volatile of the most resistant rice variety (Rathu Heenati (RH)) was preferred by BPH than those of the other varieties, with the exception of Gled Plah Chawn. However, the relative BPH preference for volatiles from the RH variety decreased during BPH infestation. When rice plants were infested by BPH, the numbers of VOCs and these quantities decreased. In the RH variety, the emission of essentities found without BPH infestation ceased during infestation by BPH. During the BPH infestation, rice plants started to emit new VOCs that were not detected before the BPH infestation started. In conclusion, we discovered that rice plants defended against BPH by changing VOC components during BPH infestation and β-Sesquiphellandrene was likely the most effective component.

Durian (Durio zibethinus L.) is an economically important crop in the southern and eastern parts of Thailand. The occurrence of die-back disease caused by plant pathogenic fungi poses a serious threat to the quality and quantity of durian products. However, the identification of causal agents has been a subject of mixed information and uncertainty. In this research, we conducted a comprehensive investigation of die-back disease in nine durian plantations located in Thailand. By analyzing a total of 86 Fusarium isolates obtained from infected tissues, we aimed to provide clarity and a better understanding of the fungal pathogens responsible for this economically significant disease. Through a combination of colony characteristics, microscopic morphology, and a multilocus sequence analysis (MLSA) of the internal transcribed spacer (ITS) region, translation elongation factor 1-α (TEF1-α) gene, and RNA polymerase II gene (RPB2) sequences, we were able to identify and categorize the isolates into three distinct groups, namely, Fusarium incarnatum, F. solani, and F. mangiferae. Koch’s postulates demonstrated that only F. incarnatum and F. solani were capable of causing die-back symptoms. This research represents the first report of F. incarnatum as a causal agent of die-back disease in durian in Thailand. Additionally, this study uncovers the association of ambrosia beetles and F. solani, highlighting the potential involvement of E. similia in facilitating the spread of die-back disease caused by Fusarium in durian.

We provide an annotated checklist of species of bark and ambrosia beetles (Curculionidae: Platypodinae and Scolytinae) recorded from Iran, with information on distribution, host trees, biology and taxonomy. Two species of Platypodinae and 79 species of Scolytinae are recorded. Hypothenemus crudiae (Panzer, 1791), Scolytus koenigi Schevyrew, 1890 and Xyleborus monographus Fabricius, 1792 are recorded for the first time from Iran. Previous records of three further species are considered dubious and require confirmation.

Termites of the genus Macrotermes (Termitidae: Macrotermitinae) are serious agricultural and structural pests, which also play vital roles in ecosystem functioning, and are crucial for the maintenance of tropical biodiversity. They are widely distributed, mainly in Southeast Asian countries; however, the parasitism of termites has been little researched. This research was conducted to identify and study the ecology of the parasitoids of termites at Kasetsart University, Kamphaeng Saen Campus, Nakhon Pathom, Thailand. Macrotermes gilvus (Hagen) soldier termites were collected from 25 mounds. In four of the 25 mounds, scuttle fly larvae were found inside the bodies of the soldier termites, and adult flies were found in all of the mounds. Some of the larvae successfully developed to pupae under laboratory conditions. The percentages of parasitized major soldier termites collected from the four mounds were 43.79%, 47.43%, 0.86%, and 3.49%, respectively, and the percentages of parasitized minor soldier termites were 0.64%, 0.00%, 0.21%, and 0.00%, respectively. Larvae, pupae, and adult flies were identified using both morphological and molecular identifications. Molecular identification used the partial nucleotide sequences of the mitochondrial cytochrome c oxidase I (COI) gene. The results of both identification methods identified the parasitic Diptera as the scuttle fly, Megaselia scalaris (Loew) (Diptera: Phoridae). The phylogenetic analysis of the 23 scuttle fly samples (11 larvae, 7 pupae, and 5 adults) classified them into two clades: (1) Those closely related to a previous report in India; (2) those related to M. scalaris found in Asia and Africa. This is the first discovery of M. scalaris in M. gilvus. Further investgation into termite parasitism by M. scalaris and its possible use in the biological control of termites is needed.

Aceria guerreronis Keifer (Acari: Eriophyidae) is a phytophagous mite that is one of the serious pests of coconut fruits worldwide. Chemical controls have been and continue to be the primary means of control. Because pesticide compatibility with natural enemies is a major concern for IPM systems. The aim of this study was to explore the contact toxicity and egg hatching inhibition of conidia suspension and crude ethyl acetate extract of Hirsutella thompsonii F.E. Fisher against adults and eggs of A. guerreronis Keifer. The results indicated that six isolates of H. thompsonii F.E. Fisher were evaluated for their pathogenicity against eggs and adults of the coconut mite (A. guerreronis Keifer), and H. thompsonii F.E. Fisher TBRC 6805 and TBRC 6933 resulted in the highest mortality (100%) on the 3rd day post-inoculation (DPI). The crude ethyl acetate extracts 5% (w/v) of H. thompsonii F.E. Fisher isolates TBRC-BCC 13865 showed the highest mortality to eggs (92%) and adults (98%) of A. guerreronis Keifer, and the LC50 value was 2.629% (eggs) and 1.704% (adults) after 72 h posttreatment. This study shows that H. thompsonii F.E. Fisher, a fungus well known for controlling biotic stress brought on by insect pests, can also have potential for the development of novel bioacaricides to control A. guerreronis Keifer in an integrated pest management program.