Influence of Scirpophaga incertulas (Lepidoptera: Pyralidae) on deepwater rice

1990 ◽  
Vol 80 (3) ◽  
pp. 301-308 ◽  
Author(s):  
Zahirul Islam

AbstractThe influence of the lepidopteran stem borer Scirpophaga incertulas (Walker), the most important pest of deepwater rice (Oryza sativa) in south-east Asia, on plant and grain yield was investigated in Bangladesh during 1982–85. Four mechanisms of crop loss were identified: (i) deadhearts at the vegetative stage, (ii) loss of damaged but apparently healthy stems in flood water, (iii) white-heads at the reproductive stage and (iv) the effect of late season stem damage on panicles. A great proportion of damaged stems was not visible and damage symptoms were found to be an unreliable indicator for the assessment of borer activities in the field, and did not represent the actual yield loss. Stem damage had a negative influence on the stem density, with reduced panicle density and grain yield. Stem borer damage also seemed to reduce the elongation ability of the rice stem causing them to rot. Late season stem damage reduced the number of filled grains, mean grain weight and panicle weight and increased grain sterility. These effects were related to severity and position of damage. The average estimated yield loss due to S. incertulas was about 17% which took place during the last 11 weeks (from flood peak to crop maturity) of the deepwater rice season (32 weeks).

1988 ◽  
Vol 78 (2) ◽  
pp. 209-225 ◽  
Author(s):  
Brian Taylor

AbstractUsing several methods, claims that stem-borers, especially Scirpophaga incertulas (Walker), cause serious crop loss in deepwater rice were tested in Bangladesh. Insecticides were used to control different borer broods. Early season, pre-flood applications reduced infestation, but did not affect yield. One to three mid- to late-season applications of monocrotophos at 250 g a.i./ha significantly reduced infestation and/or whitehead numbers, with yield savings (7-10%) similar to those which earlier workers obtained by applying diazinon 20 times in a season. In each of six years, tiller populations peaked before flooding, then steadily declined until harvest, but stem-borer infestation varied, remaining low until late season in two of the years. In 1981, infestation lower than 24% pre-flood and 42% at harvest did not affect yield. In 1982, eighty-four correlation calculations showed no consistent significant effects of infestation (27-60%, C.V. 40%) on yield (25 000 stems were dissected). Anatomical studies of elongated stems revealed S. incertulas feeding neither causes significant structural damage nor seriously interrupts nutrient flow; also, the passage of a larva through a nodal septum is not detrimental. Irrespective of stem-borer attack, the submerged lower internodes commonly die, the fibrous remains anchor the upper stem, and nodal roots take over nutrient uptake. Studies of panicle-bearing stems (n = 838) showed that, even with 97% stem infestation, most yield loss results from infestation of the terminal internode and is manifested predominantly as whiteheads. In a specific study, 94% whiteheads (n = 205) were associated with terminal internode infestation, where larval feeding in the narrow stem had disrupted food conduction, so preventing grain-filling. The apparent tolerance of S. incertulas by deepwater rice varieties is consistent with their being a primitive group of cultivated rices.


2018 ◽  
Vol 20 (2) ◽  
pp. 40-45
Author(s):  
Irma Cahyoko ◽  
Dwinardi Apriyanto ◽  
Kanang S. Hindarto

[INCIDENCE OF THE RICE YELLOW STEM BORER (Schirpophaga incertulas Walker) ON THREE RICE VARIETIES IN KEMUMU, NORTH BENGKULU]. Rice yellow stem borer (RYSB), Schirpophaga incertulas Walker, often causes yield loss in irrigated rice field. Dead heard and white ear head are the common symptomps resulted from the larval damage. The use of resistant varieties may reduce the risk of yield loss, but the resistance may lose quickly as the varieties are continually grown in a large area. The assessment of the insect incidence in rice field is necessary in order to determine the status of the pest for certain period of time. The objective of the study was to determine the incidence and damage incurred by RYSB in three rice varieties, Mekongga, Cibogo, and Situ Bagendit at farmer rice fields. A survey was conducted in December 2017-February 2018 in Kemumu, North Bengkulu Regency. Observation of RYSB was made on randomly selected 30 hills from + 1 ha area for each variety that was located adjacent to each other. Grain yield was measured from the sampled hills and from 3 plots of 9 m2 . Weight of 1000 grain was measured from grain of three sampled hills. The results revealed that the incidence of RYSB was low, as indicated by the presence of egg mass and larvae of RYSB, and no significant difference was found among the three varieties. Nevertheless, the average cumulative number and percentage of dead heart and white ear head was significantly lower in Mekongga than those of Cibogo and Situ Bagendit. In term of grain yield, however, Mekongga outperformed the other two varieties. The low incidence of RYSB might suggest that growing different variety practiced by local farmers was able to suppress pest population, and therefore it should be implemented in all main areas of rice production.


2021 ◽  
Author(s):  
Sushant Kumar ◽  
Hem Singh

Abstract The present investigation was based on the management of Yellow stem borer which is a major pest of Basmati rice crop in India. All the treatments were applied to control this pest when it reached on its ETL level. The data recorded one day before of first spray and 3, 7, 10 days after of each spray. The observation revealed that all the treatments were found significantly superior over untreated control. Among the all treatments Fipronil 5 SC was found most effective followed by Imidacloprid 17.8 SC, Cartap hydrochlorid 4 G. Among the bio-pesticides B. bassiana was most effective after the chemical pesticides followed by M. anisopliae and V. lacani. The field treated with fipronil 5 SC produced the highest grain yield (38.35 q/ha) and Imidacloprid 17.8 SC was placed on second place with 37.26 q/ha grain yield followed by Thiamethoxam 25 WG (36.05q/ha) and Cartap hydrochloride 4G (33.87 q/ha).


ENTOMON ◽  
2018 ◽  
Vol 43 (4) ◽  
pp. 257-262
Author(s):  
Atanu Seni ◽  
Bhimasen Naik

Experiments were carried out to assess some insecticide modules against major insect pests of rice. Each module consists of a basal application of carbofuran 3G @ 1 kg a.i ha-1 at 20 DAT and Rynaxypyr 20 SC @ 30 g a.i ha-1 at 45 DAT except untreated control. All modules differ with each other only in third treatment which was applied in 65 DAT. The third treatment includes: Imidacloprid 17.8 SL @ 27 g a.i ha-1, Pymetrozine 50 WG @ 150 g a.i ha-1, Triflumezopyrim 106 SC @ 27 g a.i ha-1, Buprofezin 25 SC @ 250 g a.i ha-1; Glamore (Imidacloprid 40+Ethiprole 40% w/w) 80 WG @ 100 g a.i. ha-1, Thiacloprid 24 SC @ 60 g a.i ha-1, Azadirachtin 0.03 EC @ 8 g a.i ha-1, Dinotefuran 20 SG@ 40 g a.i ha-1 and untreated control. All the treated plots recorded significantly lower percent of dead heart, white ear- head caused by stem borer and silver shoot caused by gall midge. Module with Pymetrozine 50 WG @ 150 g a.i ha-1 treated plot recorded significantly higher per cent reduction of plant hoppers (>80% over untreated control) and produced higher grain yield (50.75 qha-1) than the other modules. Among the different treated modules the maximum number of spiders was found in Azadirachtin 0.03 EC @ 8 g a.i ha-1 treated module plot followed by other treatments.


ENTOMON ◽  
2020 ◽  
Vol 45 (3) ◽  
pp. 181-188
Author(s):  
T. Sharmitha ◽  
C. Gailce Leo Justin ◽  
S. Sheeba Joyce Roseleen ◽  
P. Yasodha

Three species of parasitoids viz., Telenomus dignus Gahan, Trichogramma japonicum, Ishii and Tetrastichus schoenobii Ferriere were recorded from the egg masses of rice yellow stem borer, Scirpophaga incertulas (Walker) in a field study. The extent of parasitism was high during Rabi (43.33 – 93.33 %) and low during Kharif (0 - 40.00 %). Parasitism by T. dignus was maximum in October (50.00 %), T. japonicum, in November (23.08 %) and T. schoenobii in February (55.55 %). dignus and T. schoenobii in combination parasitized maximum number of egg masses (41.82 %). Multiple parasitism by the three species was high in December (8.33 %) and January (7.14%). Parasitic potential was maximum, when T. schoenobii alone parasitised the egg masses followed by T. dignus and T. schoenobii in combination. Host density in the field influenced the extent of parasitism.


2010 ◽  
Vol 46 (No. 1) ◽  
pp. 21-26 ◽  
Author(s):  
V. Šíp ◽  
J. Chrpová ◽  
O. Veškrna ◽  
L. Bobková

Reactions to artificial infection with Fusarium graminearum isolates and a new fungicide Swing Top were studied in nine winter wheat cultivars evaluated in field experiments at two sites for three years for expression of symptoms, deoxynivalenol (DON) content in grain and grain yield. The results demonstrate a pronounced and relatively stable effect of cultivar resistance on reducing head blight, grain yield losses and contamination of grain by the mycotoxin DON. It is advantageous that the moderate level of resistance to Fusarium head blight (FHB) was detected also in two commonly grown Czech cultivars Sakura and Simila. Average fungicide efficacy for DON was 49.5% and 63.9% for a reduction in yield loss, however, it was found highly variable in different years and sites. The joint effect of cultivar resistance and fungicide treatment was 86.5% for DON and even 95.4% for reducing the yield loss. A very high risk was documented for susceptible cultivars and also the effects of medium responsive cultivars were found to be highly variable in different environments and therefore not guaranteeing sufficient protection against FHB under different conditions.


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