The Detection of Wolbachia in Tea Green Leafhopper (Empoasca onukii Matsuda) and Its Influence on the Host

Tea green leafhopper (Empoasca onukii Matsuda) is a critical pest in tea production. Wolbachia has attracted much attention as a new direction of pest biological control for its ability of manipulating the hosts’ reproductive biology. In this work, we focused on the detection of Wolbachia in tea green leafhopper and its effect on host reproduction and development. Polymerase chain reaction (PCR), real-time PCR, and fluorescence in situ hybridization (FISH) techniques were used to detect the distribution of Wolbachia in tea green leafhopper. Wolbachia infection levels were different in different organs of hosts in different insect stages. In addition, comparison between the infected populations and cured population (treated by tetracyclines) revealed that presence of Wolbachia apparently influenced the growth, life cycle, and other reproductive factors of tea green leafhopper, caused, for example, by cytoplasmic incompatibility (CI), thereby reducing number of offspring, shortening lifespan, and causing female-biased sex ratio. This research confirmed that the bacteria Wolbachia was of high incidence in tea leafhoppers and could significantly affect the hosts’ reproductive development and evolution.

The effectiveness of the entomopathogenic fungus Metarhizium anisopliae in controlling the green leaf hopper (Nephotettix virescens)

Green leafhopper (Nephotettix virescens) is one of the major pests on rice plants that can be a vector of tungro disease. Current pest control using insecticides by farmers is very worrying because in general it is not as recommended which can cause disturbances in the balance of the ecosystem, so it is necessary to use more environmentally friendly control alternatives, one of which is the use of entomopathogenic fungi that are targeted and do not cause the death of natural enemies. The potential of entomopathogenic fungi as biological control agents needs to be continuously developed to reduce the use of insecticides, one of which is the fungus Metarhizium anisopliae which is a type of entomopathogenic fungus that can kill insect pests. The purpose of this study was to determine the effect of several concentration and application method of M. anisopliae on the mortality of the green leafhopper (Nephotettix virescens). The study was conducted in the Laboratory and Greenhouse of the Tungro Disease Research Station starting from February - April 2020 using a two-factor factorial design in a completely randomized design (CRD). The first factor was the application method consisting of two treatments, namely the spray method (A1) and dip method (A2) while the second factor was the conidia density of Metarhizium anisopliae with 4 levels, namely 0 (C0) as control, conidia density 106 (C1) conidia density 107 (C2) conidia density 108(C3). Each treatment was repeated three times. The results showed that the concentration of 106 by dipping application showed the fastest average death time of green leafhopper imago, which occured after 4 days of application, while the fastest average death time of green leafhopper nymph was 3.67 days after application at a concentration of 10 7 by dipping applications.

Bio-intensive integrated control of tungro disease in the rice field

This research aims to gain the technology of bio-intensive integrated control of tungro. The experiments were done in a split-plot design with three replications. The main plot consisted of Bio-intensive integrated control, compared to Conventional control. The subplots are: 1) the susceptible varieties (TN1), 2) green leafhopper–resistant varieties (IR64), and 3) tungro resistant varieties (Inpari 9 Elo). The subplots are 10 m x 10 m, and every subplot is replicated three times. Variables observed were the population density of green leafhopper (GLH) and the predators, the percentage of tungro incidence, and the grain yield. The results showed that the population of GLH in the plots of bio-intensive integrated control (27.32, 2.34, 4.83, and 5.16) was lower than the population of GLH in conventional control (34.00, 21.17, 7.84, and 6.50). The GLH population density tends to be higher in varieties TN1 than the other varieties both in bio-intensive and conventional control. It is found that 12 species of predator exist in all varieties of bio-intensive control and conventional plots. At 8 WAT the infection of RTV on all varieties in bio-intensive plot control is lower (0.67 - 2.67%) than the incidence of tungro in conventional plot control (3.00 - 8.67%).

PREFERENCE TEST OF GREEN LEAFHOPPER (Nephotettix virescens Distant) TO SOME TUNGRO-RESISTANT PROMISING LINES

Preference test of green leafhopper (GLH) Nephotettix virescens Distant to some tungro-resistant promising lines. Tungro is the most important diseases of the rice plant, caused by two types of viruses, namely Rice Tungro Bacilliform Virus (RTBV) and Rice Tungro Spherical Virus (RTSV), transmitted by green leafhopper (GLH) especially Nephotettix virescens Distant in a semi- persistent manner. The aim of this research was to study some of the varieties dislike (resistant) to GLH and resistant to rice tungro virus. The study was conducted on Januari to August 2019 at Green House of Indonesian Tungro Disease Research Station and at farmer’s field in Polman West Sulawesi. The experiment in the green house was preference and survival test using a Randomized Completely Block Design (RCBD) with three replications. The materials consisted of 48 tungro-resistant promising lines and 2 varieties as a check. The field experiment using an augmented design with four blocks. Every block consisted of 20 promising lines and four varieties of checks (Ciherang, Tukad Unda, Inpari 9 Elo, and IR 64). Variables observed were the number of GLH present and survival in promising lines, the population of GLH at the field, the percentage of tungro incidence, the filled with spikelet number, the unfilled of spikelet number, the weight of 1000 grain, and the grain yield at 14% moisture content. The results showed that ten promising lines was dislike (resistant) to GLH and resistant to rice tungro virus with the percentage of tungro incidence lower or equal than resistant check varieties (Inpari 9) and had high yield potential (6,2 – 10,2 t/ha).