Stem Borer Incidence Research Articles

Incidence and distribution in sorghum of the spotted stem borer Chilo partellus and associated natural enemies in farmers' fields in Andhra Pradesh and Maharashtra states

A series of surveys was carried out in farmers' fields in two major sorghum-growing states of India (Maharashtra and Andhra Pradesh) during the 1994 and 1995 cropping seasons to determine distribution, abundance, and economic importance of the spotted stem borer Chilo partellus Swinhoe and associated parasitoids in sorghum. Stem borer incidence and distribution varied significantly between the two states. In Maharashtra, the highest incidence was recorded in Amravati district(40%), followed by Yavatmal(39%). In Andhra Pradesh, the highest incidence and damage were recorded from Medak (31%), followed by Mahbubnagar (30.3%). The natural enemies recorded in the survey included three larval parasitoids, viz. Cotesia ruficrus (Haliday) and C. flavipes Cameron, and Sturmiopsis inferens Townsend and one pupal parasitoid Xanthopimpla stemmator Thunberg. While species composition did not vary between the two states, species predominance varied considerably, such that Cotesia spp. were predominant in Maharashtra, and S. inferens in Andhra Pradesh.

Patterns of stem borer incidence and damage to two cultivars of maize in the field

Two indigenous maize cuitivars, Inbred A and Nyamula, were evaluated in a field trial for their susceptibility/resistance to Chilo partellus at the artificial infestation levels of 10 larvae/plant and 20 larvae/plant. Foliar damage was caused predominantly by C. partellus, but stem-tunnelling was caused not only by C. partellus but also by another species of borer, Eidana saccharina, which invaded the crop during the tassel emergence stage and persisted during harvest. In the 10-week old crop, the number of C. partellus recorded on Nyamula was greater than on Inbred A, but the incidence of injury to foliage and stem-tunnelling on the two cuitivars was the same. At harvest the degree of damage to the two cuitivars varied. At the infestation level of 20 larvae/plant, the cuitivars suffered equal stem-tunnelling. There was a significant negative correlation between stem-tunnelling and yield for Inbred A, but the correlation was not significant for Nyamula. At the infestation level of 10 larvae/plant, the correlation between stem-tunnelling and yield was not significant for either of the cuitivars, perhaps, due to excessive activity of E. saccharina in the stalks of Inbred A.

Comparative observations on the pest and disease incidence and yield losses of Japonica, Indica and Japonica × Indica rices

Abstract Comparative field observations of pest incidence on five selected varieties each of Japonica, Indica, and Japonica × Indica rice types indicated that tungro incidence was relatively higher on Japonica varieties, while stem borer incidence at heading stage was higher on Indica varieties. No differences in the relative abundance of other pests on these rice types were observed. Insecticide treatment and caging of plants reduced pest incidence on all varieties. Plant growth and yield of insecticide‐treated plants were significantly higher than unprotected plants. Caging reduced the number of tillers but the yields remained higher than unprotected plants. Yield loss estimated by the insecticide protection method was higher at 39% than that by the caging method at 25% overall. There was a significant positive correlation between yield loss estimated by the two methods in Indica and Japonica × Indica varieties and no such relationship in Japonica varieties.

EFFECT OF SLOW-RELEASE NITROGEN FERTILIZERS AND OF FOLIAR APPLICATION OF NEEM PRODUCTS ON RICE PESTS

An on-farm trial was conducted at Manamadurai in Tamil Nadu with the objective of studying the influence of slow-release fertilizer nitrogen and the effect of sprays, with simple extracts of neem products on the incidence of rice pests. Both neem. cake-coated urea and coalter-coated area significantly reduced the incidence of what maggot and leaffolder but had no significant effect on the incidence of stem borer. Green leafhopper population was lower in neem cake-coated urea while gall midge incidence was less in conltar-coated urea. Foliar application of neem seed extract at 2% and neem cake extract at 5% were ineffective in controlling major rice posts.

Some factors of upland rice tolerance to stem-borers in West Africa

Stem-borer incidence on upland and irrigated rice varieties is compared under natural or artificial infestation, and with simulated damage by sectioning tillers. In the early stages, Diopsids lay more eggs on irrigated varieties, but these are less suitable for the development of Diopsids larvae than upland varieties, whose stems are thicker.

Seasonal occurrence of the yellow stem borer Scirpophaga incertulas (Walker) on deepwater rice in Bangladesh and Thailand

Deepwater rice is grown in South and Southeast Asia on 11 million hectares flooded deeply during the monsoon. Surveys for the incidence of stem borers in deepwater rice in Bangladesh from 1977 to 1980, and in Thailand during 1981 and 1982, showed that borer incidence and species composition were remarkably similar. Scirpophaga incertulas (Walker) usually comprised more than 90% of the borer population and was almost exclusively present during the main flooding period. Chilo polychrysus (Meyr.) comprised 11% and Sesamia inferens (Walker) 6% of the population in the pre-flood and ripening stages. Low borer activity in the early part of the season was explained by a low nucleus population, the synchronous planting of deepwater rice, and severe moisture stress and high temperatures in the pre-flood period. In Bangladesh, a severe drought in 1979 limited Scirpophaga incertulas populations to unusually low levels until the flowering stage. In Thailand, drier conditions, the lack of an intervening rice crop in the dry season and a longer pre-flood period, appeared to severely restrict early season borer activity. The onset of flooding and stem elongation provided a more favourable environment for S. incertulas. Borer activity increased steadily during the first 3–4 months of flooding, to average 23% damaged stems (26 m −2) and 13 borer immature stages/100 stems (13 m −2) by the flowering stage. Borer activity continued at about the same level as the water receded, to reach maximum annual levels of 38–44% damaged stems (35 m −2) at the late-ripening stage. At harvest, 60% of the fields were at outbreak level (>40% damaged stems). Such high levels of damage are explained by the long growth period of deepwater rice, favourable weather during the flooding period, and the optimum habitat of the elongated stem. S. incertulas populations then crashed to low levels; the larvae entering diapause in the field stubble. Although related to actual damage, the deadheart and whitehead symptoms grossly under-estimated the extent of stem damage.

Planting Time and Stem Borer Incidence in Badeggi, Nigeria

Planting Time and Stem Borer Incidence in Badeggi, Nigeria

A rapid method for the assessment of rice stem borer incidence

A rapid method for the assessment of rice stem borer incidence

A reliable measure for the estimation of yield loss in different stages of rice crop due to stem borer incidence in lower Sind

A reliable measure for the estimation of yield loss in different stages of rice crop due to stem borer incidence in lower Sind

Influence of Fertilization on Stem Borer Incidence on Four Rice Cultivars

Influence of Fertilization on Stem Borer Incidence on Four Rice Cultivars

Stem Borer Incidence in Deep-Water Rice

Stem Borer Incidence in Deep-Water Rice

Estimation of Stem Borer Damage in Rice Fields

Rice farms in Nueva Ecija and Laguna Provinces, Philippines, were surveyed to evaluate sampling procedures for estimating stem borer infestation and consequent yield losses. Using the screening technique, percent incidence was slightly underestimated because of induced tillering in infested hills. No definite distribution pattern of stem borer incidence was found across rice fields (center, periphery). Relationships between yield and percentage of incidence were exponential. To accurately assess yield loss, dead hearts and white heads should each be measured once. Single hills were not effective as sampling units because plant vigor varies widely among hills. When areas were used as sampling units, not only percentage incidence but also distribution among hills influenced yield loss.

Weather and the Incidence of Stem-borer (Chilo zonellus, S) in Co. 12 Irrigated Summer Cholam at Coimbatore

The incidence of pests and diseases is closely knit with the prevailing weather conditions. With a view to understand the nature of such influence, experiments were started in 1954, in the four irrigated crops of cholam, ragi, cotton and groundnut raised at the Central Farm, Coimbatore. From the date of sowing to the date of harvest, micro-climatic observations were recorded amidst the crops both morning and evening at stipulated hours and also weekly observations on pests in collaboration with the Entomologist, Coimbatore. The data so collected for fourteen years from 1954 to 1967 in CO.12 irrigated cholam raised as a summer crop at Coimbatore were examined with particular reference to stem borer, Chilo zonellus, S., which is a major pest of jowar, maize and sugarcane and also at times bajra and rice (Trehan and Butani, 1949), together with the macro-climatic observations recorded at Agricultura! Meteorological Observatory, Agricultural College and Research Institute, Coimbatore.