White Stem Borer Scirpophaga Research Articles

Assessment of Yield Losses Due to White Stem Borer Scirpophaga fusciflua (Hampson) in Rice

Field experiments were conducted to assess the extent of losses occurring in rice crop due to the white stem borer (WSB) Scirpophaga fusciflua (Hampson) at different stages of crop growth. Results revealed that maximum infestation in terms of deadhearts and white ears was 11.6% at maximum release level (6 larvae/ hill) and the least (6.2%) at 2 larvae/ hill. The avoidable losses varied from 7.5 to 32.3%. The infestation % of released larvae was lowest to the economic threshold level.

Peranan Parasitoid Telur Penggerek Batang Padi Putih Scirpophaga innotata (Walker) Pada Berbagai Fase Pertumbuhan Tanaman Padi

White stem borer Scirpophaga innotata Walkers is known as a species that always causes loss of rice yields in Indonesia and the Asia region and Australia. White stem borer attacks all stages of rice plant growth starting in the nursery until harvest. Until now, synthetic chemical pesticides are still a mainstay of farmers in controlling these pests. Then it is necessary to promote biological pest management, the use of biological agents is pest management technology because a save, economical and effective. Biological control through multiplication and parasitoid release needs to be focused on parasitoid it has adapted to the local environment. This study aims to examine the role of egg parasitoid S. innotata through the type and level of egg parasitization at various phases of rice plant growth. This research was conducted by collecting as many white rice stem borer eggs as possible based on the growth phase of rice plants, i.e. age 11-25 days after planting (DAP), 26-40 DAP, 41-55 DAP, 56-70 DAP, and 71-85 DAP. Observations were made by counting hatching and non-hatching eggs, as well as the type and number of parasitoids that appeared. The results show that the egg parasitoid found was Trichogramma japonicum Ashmead, Tetrastichus schoenobii Ferriere, Telenomus rowani Gahan. The highest level of egg parasitization is at 71-85 DAP.

Intercropping of Rice Varieties Reduces Green Leafhopper and White Stem Borer Infestation

A system of crop management by intercropping of diverse rice varieties in the field provides an effective way to control rice disease, but its effectiveness to control rice pest insects is not well known. Our research evaluated the impact of four rice varieties planted by strip intercropping on populations of green leaf hopper Nephotettix virescens and incidence of rice white stem borer Scirpophaga innotata in Sulawesi, Indonesia. The average number of green leafhopper insects caught by five consecutive passes with a sweep net on Pulut putih, Lapang, Fatmawati, Ciliwung varieties planted by monoculture, between 30 and 58 days after planting in a Sidrap plantation was respectively 0.6 - 4.3, 1.0 - 6.0, 1.7 - 6.7 and 2.3 - 6.0 adults, while in rice grown in strip intercropping the catch was respectively 0.7 - 2.5, 0.4 - 2.7, 0.5 - 2.6, and 1.4 - 3.5 adults. The average incidence of white stem borer observed between 30 and 65 days after planting on the same varieties in Sidrap planted by monoculture was respectively 1.8 - 9.7, 5 - 40%, 10.0 - 23.2, and 0.0 - 28.5% and in the strip intercropping was respectively 1.5 - 11.6%, 8.0 - 27.5%, 4.2 - 12.8%, and 2.0 - 7.2%. The average incidence of white stem borer in the Wajo plantation using monoculture was respectively 22.5 - 35.4%, 30.2 - 60.5%, 24.0 - 35.0%, and 17.5 - 28.5% and in the rice planted by strip intercropping was respectively 26.0 - 36.1%, 28.1 - 57.0%, 24.0 - 35.0%, and 15.0 - 23.2%. These data demonstrate that intercropping of rice varieties results in a reduction of rice pest infestation.

Shapes of mandibles of white stemborer Scirpophaga innotata (Walker, 1863)larvae associated with different rice varieties

Rice stem borers are considered the most serious insect pest of rice in Asia. The white stem borer Scirpophaga innotata (Walker, 1863) is the most prevalent among the different species that exist in the Philippines. This pest uses its strong mandibles to penetrate and feed on its plant host. Rice varieties of various level of resistance were deployed in different geographical locations in the Philippines but infestations were still observed and have contributed to economic losses to the farmers. Although differences in the resistance level among rice varieties makes an important factor in the control of the pest, no rice variety has been reported to be completely resistant against rice stem borer attacks. Several reports have indicated however that the level of damage caused by rice stem borer attacks differs. Thus it was the major objective of this study to determine if populations of white stem borer showed intraspecific variation between different geographical locations and between rice varieties. Since the mandible of the larvae is used in penetrating the plant, this morphological part of the insect larvae was investigated. Outline-based geometric morphometric analysis was used to test the hypothesis that the mandible shape of white stem borer differ with respect to different rice varieties and geographical location. Results of the principal component analysis showed variation in the shape of the mandible among populations of white stem borer taken from different rice varieties but not in the same variety collected from different geographical locations. Results of this study further confirm the general argument that host plant resistance play an important role in the evolution of pests.

Some factors affecting white stem borer Scirpophaga innotata (Walker) (Lepidoptera: Pyralidae) injury to rice

The amount of injury to rice caused by white stem borer Scirpophaga innotata depends on cultivar, and stage of plant and insect development, as well as insect abundance. Of the cultivars tested, IR64, IR42, Cisadane and Ketan, IR64 were the most susceptible and Ketan the least susceptible to feeding damage. Third and fourth instars consumed more stem dry matter than other stages, although yield reduction depended on the number of tillers injured. On the wider stemmed Ketan, fewer tillers were injured than the narrower IR64. Larvae are more likely to move among tillers in the third instar stage, which tends to coincide with maximum tillering and may result in more tillers injured and in yield reduction. Later instar larvae burrow downwards to the internode where they pupate. Larvae appear to move less among tillers in ‘resistant’ cultivars. Management strategies should target this pest at third instar and when its abundance in the field warrants control. Fewer than 10% of the neonates establish successfully on stems, and this mortality needs to be taken into account when deciding on control, as does the ability of rice plants to compensate for injury.

White stem borer damage and grain yield in irrigated rice in West Java, Indonesia

Factors influencing the relationship between whiteheads caused by the white stem borer Scirpophaga innotata (Walker) and grain yield were investigated. We determined the effect of different numbers of whiteheads on grain yield using different cultivars, nitrogen application, and at different field locations in Cilamaya, West Java. At the same number of panicles and whiteheads per plant, yield reduction is greater in Cisadane than in IR64. With increasing nitrogen application, the range in panicle height increased. Except for Ketan, more whiteheads were recorded in shorter panicles. Two locations planted to the same cultivar showed different relationships between whiteheads and grain yield. The relationship between whiteheads and grain yield depends on the distribution of whiteheads in the field. Unless these factors have been taken into consideration, it may be difficult to make a damage prediction of white stem borer in the field.

Farmers' perceptions of the white stem borer Scirpophaga innotata (Walker), in Cilamaya, West Java, Indonesia

In connection with the white stem borer outbreak, reported during the 1989–1990 wet season in the northern part of West Java, field surveys were conducted to determine the importance of this pest to farmers, to assess their knowledge of it and to determine current control practices. The largest percentage (85%) of farmers perceived the white stem borer as important and difficult to control (22%). When farmers observe white stem borers in their fields most believe that moths migrated from other rice fields. Many farmers were uncertain that an outbreak will occur the next season, mainly because of the lack of understanding of the population dynamics of the pest and the factors causing white stem borer outbreaks. The majority of the farmers use insecticides against white stem borers including those banned by the government with the implementation of the IPM policy in 1986. An account of farmers reliance on pesticide use against white stem borers is discussed.