M Sardar
Entomology Division, Bangladesh Institute of Nuclear Agriculture, Mymensingh 2202
MR Khatun
Department of Entomology, Bangladesh Agricultural University, Mymensingh 2202
KS Islam
Department of Entomology, Bangladesh Agricultural University, Mymensingh 2202
MT Haque
Entomology Division, Bangladesh Institute of Nuclear Agriculture, Mymensingh 2202
G Das
Department of Entomology, Bangladesh Agricultural University, Mymensingh 2202
Rice; Brown planthopper; Light sources; Predators
Entomology Division of Bangladesh Institute of Nuclear Agriculture, Mymensingh, Bangladesh
Pest Management
The experiment was conducted at the net house and laboratory of the Entomology Division, BINA, Mymensingh, Bangladesh from March to July, 2016 to evaluate the effectiveness of insecticides for controlling brown plant hopper, Nilaparvata lugens of rice. The experiment was laid out in a completely randomized design with three replications. Collection and rearing of brown planthopper: Gravid females of brown planthopper were collected with the help of aspirator from infested rice fields of Bangladesh Agricultural University, Mymensingh. Immediately after collection, the insects were placed in test tube of medium size (15 cm in length). The mouth of the test tubes were then closed with pieces of fine nets and fastened with rubber bands. The collected insects were then brought to the net house of BINA and reared to build up a large population. The gravid females were immediately released on 30-40 days old rice plant of TN 1 variety grown in pots and then the pots were placed in a 0.75x0.5x0.2 m (length x breadth x height) tray which was filled with water to one third of its height, so that the soil could not dry. The potted rice plants were covered with 0.9 x 0.5 m (height x breadth) rearing cages. The plants were observed for egg laying every day. For a continuous supply of 30-40 days old rice plants, TN 1 seeds were sown in seed beds at an interval of 15 days regularly starting well ahead of commencement to the experiment. Then 15- 20 days old seedlings were transplanted in pots having 35 cm height and 25 cm diameter and containing 3.0- 3.5 kg soil. The TN 1 plants (3 hills/pot were transplanted @ 2 seedlings/hill) were allowed to grow for 30-40 days under net house condition. The pots were kept in another same size tray filled with water as previously described. All recommended cultural practices including fertilizer and insecticide application were followed for optimum plant growth. Sevin dust, an insecticide with least residual effect was used whenever necessary to protect the brown planthopper from ants. For egg laying purposes, adult brown planthopper was released in caged-fresh rice plants on every Sundays and Wednesdays in every week. The gravid or adult female brown planthopper was transferred from one used plant to another fresh plant with the help of an aspirator. After removal of the adults the plants were kept under the cages for a sufficient time so that the brown planthopper eggs on these plants can hatch and reach the adult or gravid stage. Moreover, before using the plants for the egg laying of brown planthopper, the outer leaf sheaths of each tiller were removed to eliminate any brown planthopper populations from the plants. After hatching of eggs, nymphs were provided with sufficient food plants for their growth and development. As soon as most of the insects from the new hatching became adults, the females and the males were transferred to another cage with fresh plants twice a week as mentioned earlier. These insects were preserved in new cages with dates of egg laying marked on them. The brown planthopper was provided with fresh plants for their food as and when necessary. In this way, brown planthopper populations of uniform age were established and within 3-4 generations, sufficient numbers of insects became available for the production of required numbers of nymphs and adults for the different experiments. The predator, M. discolor was maintained in the net house. For this purpose adult beetles were collected from rice field of the Bangladesh Agricultural University (BAU) farm, Mymensingh. The field collected beetles were reared in plastic pot (20 cm in height and 25 cm in diameter) covered with Mylar film cage (Mylar film cage: Hard plastic made cylindrical device). Its length is 45 cm and diameter 16 cm. The upper portion of the Mylar film cage covered with nylon net. The net was attached with the cage by the help of thread). The second instars brown planthopper on 30-40 days old potted rice plants were used as food for the beetle. Mating occurred inside the Mylar film cage and the insects were allowed to lay eggs there. The eggs were separated in petridishes (11 x 2 cm). After hatching of eggs, the grubs were transferred into test tube (20 cm). One grub was reared in each test tube providing the same food as supplied to their parents; the newly emerged adults were sexed and confined in pairs in test tube for mating and laying eggs.
Collection and rearing of wolf spider: Some sexually mature adults of wolf spider, L. pseudoannulata and adult spider with egg sac were collected from the seed bed of the rice plot of BINA, Mymensingh by using net. Each of the collected spiders was kept immediately in test tube individually. Since, the spiders are strongly cannibalistic in nature; they were confined individually in 15 cm x 7 cm glass pot. They were supplied with different stages of brown planthopper as prey on one or two 12 cm long rice stem wrapped with wet cotton in the pot. All of the spiderlings became detached from the mother after 2-3 days of hatching. When newly hatched spiderlings were detached from her mother's back, they were transferred to another same sized pot. To minimize cannibalism, small pieces of rice straw were put inside the pots, thus giving chance to separate the spiderling from one another. Since, wolf spiders prefer to live at comparatively low temperature and shady area; they were reared in the laboratory at room temperature (27±2°C). Later on the spiders were kept in Mylar film cage before using in experiments. Collection and rearing of carabid beetle: The predator, Ophionea indica was maintained in the net house. For this purpose adult beetles were collected from rice field of the Bangladesh Agricultural University (BAU) farm, Mymensingh. The field collected beetles were reared in plastic pot (20 cm in height and 25 cm in diameter) covered with Mylar film cage. The 2nd instars brown planthopper on 30-40 days old potted rice plants were used as food for the beetle. Mating occurred inside the Mylar film cage and the insects were allowed to lay eggs there. The eggs were separated in petridishes (11 x 2 cm). After hatching of eggs, the grubs were transferred into test tube (20 cm). One grub was reared in each test tube providing the same food as supplied to their parents; the newly emerged adults were sexed and confined in pairs in test tube for mating and laying eggs. Net house screening: To manage brown planthopper using different light sources an experiment was conducted in the net house of BINA. Ten brown planthoppers were taken in a Mylar film cage and put in the net house. After evening the Mylar film cage was removed and the light sources were provided. Different lux range was used in this experiment. Lux output was measured from different light sources with the help of Digital Lux Meter and the range was 30-400. Light output was 30-50 lux (candle light), 80-100 lux (kerosene lamp), 180-200 lux (bulb) and 380-400 lux (energy saving lamp). After one hour the individuals of brown plant hopper attracted by light sources were counted. The same procedure continued in three days. The experiment was replicated three times. To manage brown plant hopper by predators another experiment was conducted in the net house of BINA. Ten brown planthopper were taken in a Mylar film cage against one predator and put in the net house. The second instars brown planthopper were used as prey for the beetle and 4th & 5th instars for the spider. After 24, 48 and 72 hours the consumed individuals of brown plant hopper were counted. The experiment was laid out in a completely randomized design with three replications. Collection of data: In studying the efficacy of light sources, number of attracted brown plant hopper was recorded one hour after setting the light of different intensity. The performance of predators the consumed brown planthopper individuals were recorded at 24, 48 and 72 hours after releasing the predators in Mylar film cage. Statistical analysis: The obtained data were statistically analyzed to find out the significance of differences among the treatments. The mean values of all parameters were evaluated and analysis of variance was performed by MSTAT-C software package and the mean differences were adjudged by Duncan Multiple Range Test (Gomez and Gomez, 1984).
Progressive Agriculture 30 (3): 275-281, 2019
Journal