Dead Heart Percentage Research Articles

EFFECTS OF Azadirachta indica, Parkia biglobosa AND SYNTHETIC INSECTICIDES ON Sesamia calamistis (HAMPSON) ON GROWTH AND YIELD OF MAIZE (Zea Mays L.) IN MAKURDI

Zea mays, plays a crucial role in the dietary habits of numerous individuals residing in Nigeria. Several factors, including the presence of Sesamia calmistis and the effects of synthetic insecticides on beneficial insects and hazards to humans, contribute to the limitation of maize output. The study evaluated the effect of Azadirachta indica and Parkia biglobosa extracts on the control of S. calamistis and this experiment was carried out in two planting seasons of 2021 and 2022. The experiment was carried out at the Teaching and Research Farm, Joseph Sarwuan Tarka University, Makurdi. Three treatments; A. indica, P. biglobosa, Karate 5 EC (Lambda cyhalothrin 5 EC) and control were used. From the study, A. indica extract had a significant effect at p<0.05 on the insect population resulting in a significant increase in the yield parameters which includes the number 100 seed weight of the plant, yield in both 2021 and 2022 planting season with the mean value of 5298.21 and 5428.98 kg/ha respectively. The use of A. indica extract was observed to be effective in the control of insect population and leading to maximum productivity of maize low infestation by observing the maize plant with borers tunnels to be lower in A. indica extracts and Karate 5 EC plots with the mean value of 3.00 and 3.00 in 2021 planting season respectively at p<0.05. The percentage of dead hearts at 60 days after treatment in 2021 and 2022 cropping seasons was significant at p<0.05%, with the control plot having the highest...

Effect of date of sowing and weather factors on infestation of Atherigona soccata (Rondani) and yield parameters of forage sorghum

Ecofriendly strategies for the management of sorghum shoot fly, helps in addressing the Atherigona soccataissues related to insecticides load on forage crop. The present study was carried out to know the suitable date of sowing on damage indices of sorghum shoot fly and green fodder yield in sorghum. The staggered sowing technique at a different time intervals was used, starting from 2 fortnight of March (12 SMW) to 1 fortnight of ndthstJuly (27 SMW). Oviposition in terms of eggs per 10 plants and dead heart percentage was recorded to be low thin 18 SMW (1 fortnight of May) sown crop (eggs: 6.66 and dead heart: 25.46%), but it was found to be highest thstin 1 fortnight of July (27 SMW) sown crop (eggs: 21.95 and dead heart: 65.45%). The correlation of shoot fly stthinfestation in relation to weather parameters revealed that egg load and dead hearts were negatively correlated with maximum temperature and positively correlated with minimum temperature, relative humidity and rain fall. Green fodder yield was recorded to be highest and lowest for the crop sown on 18 SMW (409 q/ha) and 27 ththSMW (302 q/ha), respectively. The study indicated that 1 fortnight of May was the best time to escape from the stsorghum shoot fly attack.

Biochemical and Morphological Assessment of Rabi Sorghum Genotypes for Shootfly Resistance

The present investigation was conducted at Sorghum Improvement Project and Department of Biochemistry, Mahatma Phule Krishi Vidyapeeth, Rahuri, Maharashtra, India during rabi 2019–20 for assessment of rabi sorghum genotypes for shootfly through biochemical perspective. Sorghum is an important food and fodder crop of dry land agriculture. The experimental material consisted of 11 sorghum genotypes viz; RSV 1628, RSV 1023, RSV 1910, RSV 2371, RSV 1945, RSV 1838, RSV 2025, RSV 1918, RSV 1988, RSV 2391, RSV 1941, three varieties viz., Phule Vasudha, Phule Revati, M-35-1, three shootfly resistant checks viz., RSV 1188, IS 18551, RSE 3 and a susceptible check i.e. DJ 6514. The experiments were conducted under pot culture and field conditions at different stages. Resistance against shootfly in sorghum was governed by the physical and chemical genes. The morphological characters like trichome density, oviposition and dead heart percentage and biochemical attributes like polyphenol oxidase, peroxidise and chlorophyll content can be used as marker traits in shootfly resistance breeding programme to broaden the genetic base and increase the levels of resistance to sorghum. The sorghum genotype RSE 3, RSV 1945, RSV 1941, RSV 1188, and RSV 2371 recorded higher polyphenol oxidase activity at 28 DAE as compared to other genotypes. So, these sorghum genotypes are good source for shootfly resistance breeding. The genotype RSE 03, RSV 1941 and RSV 1188 exhibited positive results for shootfly resistance and can be used as donor for shootfly breeding programme.

Exploration of Sources of Genetic Resistance in Maize Genotypes Against Stem Borer (Chilopartellus (Swinhoe))

Fourteen different maize genotypes were screened for their relative resistance to maize stem borer Chilopartellus (Swinhoe) under glass house condition at National Maize Research Program, Rampur, Chitwan during two consecutive years 2018 and 2019. The design of the experiment was completely randomized design having 2 replications. The unit plot size was one row of one meter length with 50 cm row to row and 20 cm plant to plant spacing. Two second instar larva of C. partellus (Swinhoe) per plant were released two times, first at 8th leaves (vegetative) and second at 12th leaves (Before tasseling) stages. Insect damage parameters (IDPs) viz. dead heart percentage, damage % at vegetative and foliar stage, foliar injury rating (1-9) at vegetative and before tasseling stage, tunnel length (cm), exit hole number and yield per plot were recorded to study the germplasm susceptibility level. The result revealed that IDPs and yield varied significantly among the tested genotypes. Over the years, IDPs like dead heart percentage (5.17%), percent damage atpre-tasseling stage (10.6%), foliar injury level (2.25), tunnel length (10.15 cm) and exit holes (2.32) were found lower with high yield (2235 g/plot) in RML-95/ RML-96 followed by RML- 86/RML-96. Two pipeline maize hybrids RML-95/RML-96 and RML-86/RML- 96 with least damaged by maize stem borer in both years will be useful for maize stem borer resistance source.
 Bangladesh J. Agril. Res. 45(3): 293-301, September 2020

Diversity and resistance components analysis of barley landraces to barley shoot fly (Delia flavibasis)

Barley shoot fly (Delia flavibasis) is one of the destructive insect pests of barley (Hordeum vulgare L.) at seedling stage. Resistance to barley shoot fly is governed by complex traits that derived from both morphological and/or biochemical characters of the plant. These host plant characters influence the relative degree of damage caused by the insect. The study aimed to evaluate phenotypic variability and interrelationships of factors influencing barley shoot fly resistance. Five hundred eighty-five landraces and ten cultivars were tested at Sinana Agricultural Research Center on station and Goba on-farm, during 2018 and 2019 main cropping seasons using augmented design consisting six blocks. High heritability percentage was obtained for yield and shoot fly resistance components like biomass (95.38%), early seedling growth vigour (91.41%), total tillers plant−1 (89.41%), fertile tiller plant−1 (88.91%), seedling colour (85.36), plant height (82.83%), 1000 seed weight (82.53%), number of seeds spike−1 (81.80%), spike length (81.11%), oviposition (65.74%) and dead heart (61.26%). Thus, this study revealed the presence of sufficient variability among the barley landraces in the country that can be exploited for germplasm enhancement. Furthermore, the defensive characters of accessions for shoot fly strongly influence the oviposition and dead heart percentage.

Correlation study of traits associated with shoot fly resistance in recombinant inbred lines (RILs) population of sorghum [Sorghum bicolor (L.) Moench

The shoot fly resistance in sorghum appears to be a complex trait and depends upon the interaction of a number of component characters, which finally sum up in the expression of shoot fly resistance. The present study was conducted during Summer-2019 to assess the correlation and study the relationship of different plant characters with shoot fly resistance in sorghum. Observations were recorded on the shoot fly components traits viz., dead heart percentage and oviposition as well as the morphological characters viz., trichome density, leaf glossiness, seedling vigour, 100 seed weight and grain yield per plant. The experimental data were collected and analyzed for correlation. Shoot fly resistance was found to be significant and positively correlated with components traits viz., seedling vigour, glossiness and trichome density at the abaxial and the adaxial surface of leaves lamina. Whereas a hundred grains weight and grain yield per plant were showed strongly significant, but negatively correlated with dead heart percentage at 21, 28 DAE and oviposition% in 14, 21 DAE respectively. The strong correlation of grain yield and these traits could indicate that improvement of all the characters is possible simultaneously and might be used to select shoot fly-resistant lines from the segregating breeding materials for use in sorghum improvement.

Evaluation of different rice genotype against yellow stem borer (Scirpophaga incertulas Walker)

The experiment was conducted in the consecutive two years 2016 and 2017 in the field conditions. As such, based on the overall mean values of two years’ of investigations, the least percentage of dead-heart (1.87%) was recorded in case of Suraksha, followed by Kavya (4.50%), Lalat (5.59%), CR Dhan – 303 (5.94%), CR Dhan – 205 (6.77%), Sahbhagi Dhan (6.88%), CR Dhan – 304 (7.02%) and Naveen (7.27%). These rice cultures were rated as promising and resistant against dead heart incidence, caused by YSB. The susceptible rice variety, TN-1 received the highest dead-heart amounting to 19.70 percent in the present studies based overall mean of two years’ results. As such, based on the overall mean values of WE recorded during two years’ investigations, the least percentage of white ear (3.16%) was noticed in case of Suraksha which remained at par with Kavya (4.34%), Akshay Dhan (3.46%), IR-20 (4.36%), IR-36 (4.50%), IR-64 sub-1 (4.64%) and followed by CR Dhan- 304 (5.27%) CR Dhan – 303 (5.78%), Lalat (6.66%) and Sahbhagi Dhan (9.63%) and all these rice genotypes received below 10 per cent white ear, caused by the stem borer, as against the highest incidence of WE was observed in the susceptible variety, TN-1 (22.71%) in the present studies. The test genotype could be arranged in descending order of: Ac Dhan (61.15 q/ha) > Advanta-801+ (59.30 q/ha) > CR Dhan -205 (52.58 q/ha) > CR Dhan – 303 (51.16 q/ha) > Lalat (50.95 q/ha) > IR-36 (50.34 q/ha) > Abhisek (49.78 q/ha) in terms of grains yield and all these seven genotype remained statistically at par. TN-1 appeared as susceptible to yellow stem borer.

INSIDENSI PENGGEREK BATANG PADI KUNING (Schirpophaga incertulas Walker) PADA TIGA VARIETAS PADI : KASUS DI DESA KEMUMU BENGKULU UTARA

[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.

Colonization of Beauveria bassiana (Balsamo) Vuillemin strains in maize (Zea mays L.) and their efficacy against stem borer Chilo partellus (Swinhoe)

Glasshouse experiments were conducted to study the endophytic ability of six strains of entomopathogenic fungus Beauveria bassiana in maize leaf and stem tissues when applied through foliar sprays of oil formulations. B. bassiana treated and untreated control plants were artificially infested with second instar larvae of Chilo partellus to assess the stem borer damage. All six strains showed varying percent colonization and persistence in stem and leaf tissues. The mean percent colonization ranged from 16.67-46.67 % in older stem tissues and 22.22-52.22 % in young stem tissues and in leaf, it ranged from 25.56-47.78 % in older leaf tissues and 31.11-57.78 % in young leaf tissues. Among six isolates tested, Bb-45 isolate recorded the maximum mean colonization in older stem (46.67 %), older leaf (47.78%) and in young stem (52.22 %). Bb-5a isolate showed maximum mean colonization in young leaf tissues (57.78 %). Significantly lower percentage of dead hearts (2.2-11.1%) and lower stem tunneling (2.7-4.3cm/plant) was observed in B. bassiana treated plants as compared to the untreated control plants (28.86% of dead hearts and 13.41cm/plant stem tunneling).

Tank mix application of selected herbicides and insecticides for weed and insect control in transplanted rice

Post-Emergence application of two insecticide molecules chloropyriphos 200 g/ha, fipronil 50 g/ha and three herbicide molecules chlorimuron-ethyl + metsulfuron-methyl at 4 g/ha, bispyribac-sodium at 25 g/ha, cyhalofop-butyl + penoxsulam at 135 g/ha were tested alone as well as in combination with an untreated control against grass, sedge, broad-leaf weed and stem borer for their compatibility during winter seasons 2015–16 and 2016–17. Tank mix application of cyhalofop-butyl + penoxsulam + fipronil (135 + 50 g/ha) recorded lowest incidence of dead heart (0.59%), white ear (3.53%), total weed density (8 no./m2) and weed biomass (3.5 g/m2) and enhanced weed control efficiency (84.6%), grain yield (5.23 t/ha), net returns (` 40.44 x103/ha) and benefit: cost ratio (2.02). Dead heart percentage was less (0.59 to 1.55%) in sole fipronil and its combination with different herbicide than that of chloropyriphos (0.92 to 1.92%). There was no difference in grain yield of rice in treatments, which received application of cyhalofop-butyl + penoxsulam alone and with fipronil indicating the compatibility of herbicide with insecticide.

Improving biological control of stalk borers in sugarcane by applying silicon as a soil amendment

AbstractThe sugarcane stalk borers, Sesamia spp. (Lepidoptera: Noctuidae) are the most destructive sugarcane insect pests in Iran. The efficiency of Telenomus busseolae Gahan (Hymenoptera: Scelionidae) used alone or in combination with silicon fertilization was investigated for controlling the sugarcane stalk borers under field conditions. The treatments were: a combination of silicon plus multiple releases of 2,500 T. busseolae, and multiple releases of 5,000, 2,500 and 1,250 T. busseolae alone. Plots receiving no soil amendment or parasites were included as the controls. Three weeks after the first application of each treatment, 100 shoots were selected randomly from each plot and the percentage of dead heart was determined. Then, three months after the first application of parasites, the percentage of stalks damaged, the percentage of internodes bored, and the level of parasitism were determined. Finally, at harvest the percentage of stalks damaged, the percentage of internodes bored, and sugarcane quality characteristics were determined. Results indicated that the efficiency of parasitism increased when combined with an application of silicon fertilizer. The release of 2,500 T. busseolae followed by an application of silicon fertilizer decreased dead hearts to 4%, while 12% dead hearts was observed in the control plots. For the combination treatment, the percentages of stalk damage were 1.5% and 17.2%, at 3 weeks and 3 months after time release, respectively. However, the percentages of stalk damage were 35.2% and 51% when no treatment was applied. Cane quality was significantly higher with the application of silicon fertilizer plus the release of 2,500 T. busseolae, followed by releasing 5,000 Hymenoptera. The level of parasitism was also greater when parasites were released in combination with an application of silicon. We conclude that biological control by egg parasitoids can be enhanced with concurrent applications of silicon fertilizer as a soil amendment and thereby creating a more robust, Integrated Pest Management (IPM) program of stalk borers in Iranian sugarcane fields.

Effects of Integrated Pest Management on Pest Damage and Yield Components in a Rice Agro-Ecosystem in the Barisal Region of Bangladesh

Recently, recognition of negative environmental impacts associated with overuse of pesticides in the agricultural regions of Bangladesh has made it clear that unsustainable pest-control strategies must change. Integrated Pest Management (IPM) was developed for use as a tool in the production of healthy, sustainably grown food. A strategic approach to crop-pest control, IPM aims to minimize pest populations by combining environmentally friendly pest-control methods and economically viable farming practices. This study examined the impact of IPM on insect damage to crop-yield parameters in a rice agro-ecosystem. IPM methods tested were: 1) collection of egg masses; 2) sweeping (using a funnel shaped net to capture insects); 3) perching (installing a branch or pole which serves as a resting place for predatory birds); and 4) Economic Threshold Level (ETL) based insecticide application (The ETL is the point at which the value of the crop destroyed exceeds the cost of controlling the pest). We also examined the effects of prophylactic insecticide application and current management practices on rice yield. Rice-yield indicators included number of healthy tillers, number of hills, central leaf drying (Dead Heart), and grain-less panicles (White Head). For two consecutive years, the lowest percentages of Dead Heart (1.23 and 1.55) and White Head (2.06) were found in the IPM-treated plots. Further, the IPM-treated plots had higher yields (7.3-7.5 ton/ha) compared with the non-IPM treatments (6.28-7.02 ton/ha). The location of the plots appeared to be non-significant for all measured yield components. The effect of treatment on the percentage of Dead Heart, White Head, number of hills, and yield was statistically significant (p ≤ 0.05). We concluded that IPM is an effective strategy for obtaining high rice yields in sustainable rice agro-ecosystems.

Comparative Study of Integrated Pest Management and Farmers Practices on Sustainable Environment in the Rice Ecosystem

Integrated pest management (IPM) is an environmentally friendly technology. IPM is a multifaceted approach to pest management that seeks to minimize negative impacts on the environment. This technique is an important step towards providing healthy, viable food for a growing global population. The focus of this study was to examine the impact of integrated pest management in a rice agroecosystem. Currently, more than 80% of farmers rely on pesticides. IPM methods employed in our study had an impact on the number of healthy tillers and hills and grain weight. The lowest percentage of dead heart (1.03) and white head (2.00) was found in the IPM treated plots. These plots had an average yield of 7.4 tonne/ha. We found that there were significant differences between the treatment and the observed percentage of dead heart, grain weight, and yield. We conclude that IPM practices are an effective strategy for obtaining high rice yields while protecting the environment and creating a more sustainable agroecosystem. Furthermore, the need for ongoing research and training on IPM methods will be essential for creating a sustainable rice agroecosystem.

Association studies between quantitative and qualitative traits in <italic>rabi</italic> sorghum

One hundred <italic>rabi</italic> sorghum germplasm lines of diverse origin were used to estimate genetic variability parameters such as heritability, genetic advance and correlation for 15 quantitative traits. The study was conducted under rainfed conditions during <italic>rabi</italic> season. High phenotypic coefficient of variation was observed for grain yield, panicle weight, panicle length, number of primaries and dead heart percentage. High heritability coupled with high genetic advance were observed for the characters days to flowering, dead heart percentage, panicle weight panicle length, number of primaries per panicle, test weight and grain yield per plant indicating that additive gene effects were operating for these traits and selection for superior genotype was possible to bring genetic improvement in desired direction. Grain yield had positive and highly significant association with plant height, panicle weight, number of primaries, panicle weight and test weight, whereas negative and highly significant correlation with seed fat content and protein content.

Fuzzy Inference Systems for Crop Yield Prediction

Abstract.Predictionofcropyieldissignificantinordertoaccuratelymeetmarketrequire-ments and proper administration of agricultural activities directed towards enhancementin yield. Several parameters such as weather, pests, biophysical and physio morphologicalfeatures merit their consideration while determining the yield. However, these parametersare uncertain in their nature, thus making the determined amount of yield to be approxi-mate. It is exactly here that the fuzzy logic comes into play. This paper elaborates an at-tempt to develop fuzzy inference systems for crop yield prediction. Physio morphologicalfeatures of Sorghum were considered. A huge database (around 1000 records) of physiomorphological features such as days of 50 percent flowering, dead heart percentage, plantheight, panicle length, panicle weight and number of primaries and the correspondingyield were considered for the development of the model. In order to find out the sensi-tivity of parameters, one-to-one, two-to-one and three-to-one combinations of input andoutput were considered. The results have clearly shown that panicle length contributes forthe yield as the lone parameter with almost one-to-one matching between predicted yieldand actual value while panicle length and panicle weight in combination seemed to playa decisive role in contributing for the yield with the prediction accuracy reflected by verylow RMS value.Keywords. Approximate Reasoning, Crop Yield, Fuzzy Logic, Fuzzy Rule Base,Membership Functions, Physio-Morphological Features.2010 Mathematics Subject Classification. 68T10.

Identification and validation of genomic regions that affect shoot fly resistance in sorghum [Sorghum bicolor (L.) Moench

Shoot fly is one of the most important pests affecting the sorghum production. The identification of quantitative trait loci (QTL) affecting shoot fly resistance enables to understand the underlying genetic mechanisms and genetic basis of complex interactions among the component traits. The aim of the present study was to detect QTL for shoot fly resistance and the associated traits using a population of 210 RILs of the cross 27B (susceptible) × IS2122 (resistant). RIL population was phenotyped in eight environments for shoot fly resistance (deadheart percentage), and in three environments for the component traits, such as glossiness, seedling vigor and trichome density. Linkage map was constructed with 149 marker loci comprising 127 genomic-microsatellite, 21 genic-microsatellite and one morphological marker. QTL analysis was performed by using MQM approach. 25 QTL (five each for leaf glossiness and seedling vigor, 10 for deadhearts, two for adaxial trichome density and three for abaxial trichome density) were detected in individual and across environments. The LOD and R (2) (%) values of QTL ranged from 2.44 to 24.1 and 4.3 to 44.1%, respectively. For most of the QTLs, the resistant parent, IS2122 contributed alleles for resistance; while at two QTL regions, the susceptible parent 27B also contributed for resistance traits. Three genomic regions affected multiple traits, suggesting the phenomenon of pleiotrophy or tight linkage. Stable QTL were identified for the traits across different environments, and genetic backgrounds by comparing the QTL in the study with previously reported QTL in sorghum. For majority of the QTLs, possible candidate genes were identified. The QTLs identified will enable marker assisted breeding for shoot fly resistance in sorghum.

Genotype × environment interactions for shoot fly resistance in sorghum ( Sorghum bicolor (L.) Moench): Response of recombinant inbred lines

Sorghum shoot fly ( Atherigona soccata) is a serious pest that destabilizes the performance of sorghum cultivars and ultimately reduces sorghum production in many parts of the world. Identifying sorghum genotypes with stable resistance to shoot fly is important as it helps to reduce the cost of cultivation and stabilizes yields. In the present study, our objective was to identify stable shoot fly resistant genotypes among 385 recombinant inbred lines (RILs) of a cross between a susceptible parent and a resistant parent. We evaluated this set of RILs in eight environments over three years (2006–2008) for shoot fly resistance and component traits. Non-significant genotype–environment (G × E) linear component and significant pooled deviation for deadheart percentage indicated that the performance of genotypes was unpredictable over the environments. However, five lines had deadheart percentages much less than the population mean with regression coefficient ( bi) values close to unity, and non-significant deviation from regression, indicating that they have stable shoot fly resistance and are well adapted to all the environments. Additive main effect and multiplicative interaction (AMMI) analysis partitioned main effects into genotype, environment and G × E interacts with all the components showing highly significant effects (p < 0.001). Environment had the greatest effect (69.2%) followed by G × E interactions (24.6%) and genotype (6.2%). Low heritability and high environmental influence for deadheart percentage suggested that shoot fly resistance is a highly complex character, emphasizing the need for marker assisted selection. We observed transgressive variation in the RIL population for all the traits indicating the contribution of alleles for resistance from both resistant and susceptible parents. Since the alleles for shoot fly resistance are contributed by both resistant and susceptible parents, efforts should be made to capture favourable alleles from resistant and susceptible genotypes.

Genetic transformation and pyramiding of aprotinin-expressing sugarcane with cry1Ab for shoot borer (Chilo infuscatellus) resistance

We evaluated the insecticidal toxicity of Cry1Aa, Cry1Ab and Cry1Ac toxins against neonate larvae of sugarcane shoot borer Chilo infuscatellus Snellen (Lepidoptera: Crambidae) in vitro on diet surface. With the lowest LC(50) value, Cry1Ab emerged as the most effective among the three toxins. Sugarcane cultivars Co 86032 and CoJ 64 were transformed with cry1Ab gene driven by maize ubiquitin promoter through particle bombardment and Agrobacterium-mediated transformation systems. Gene pyramiding was also attempted by retransforming sugarcane plants carrying bovine pancreatic trypsin inhibitor (aprotinin) gene, with cry1Ab. Southern analysis confirmed multiple integration of the transgene in case of particle bombardment and single site integration in Agrobacterium-mediated transformants. The expression of cry1Ab was demonstrated through Western analysis and the toxin was quantified using ELISA. The amount of Cry1Ab protein in different events varied from 0.007 to 1.73% of the total soluble leaf protein; the events transformed by Agrobacterium method showed significantly higher values. In in vivo bioassay with neonate larvae of shoot borer, transgenics produced considerably lower percentage of deadhearts despite suffering feeding damage by the borer compared with the untransformed control plants. Expressed Cry1Ab content was negatively related to deadheart damage. Aprotinin-expressing sugarcane pyramided with cry1Ab also showed reduction in damage. The potential of producing sugarcane transgenics with cry1Ab and aprotinin genes resistant to early shoot borer was discussed in the light of the results obtained.

The Effects of Weed Residue Management on Pests, Pest Damage, Predators and Crop Yield in Upland Rice in Côte d'Ivoire

ABSTRACT The effects of weed residues on the abundance and activity of generalist arthropod predators and insect pests and on rice yields in upland rice were studied. Weed residues were placed in the experimental plots in three ways: (1) residues left in situ where weeds are uprooted; or (2) placed in small piles throughout the field; or (3) removed from the field but heaped at the edges to be burnt when dry. The study investigated the effects of residue disposal in upland rice under research station conditions designed to simulate conditions in farmers' fields. Spider activity was significantly greater in plots with scattered residues and strips of residue and least in plots from which residues had been removed. Staphylinid beetle activity was significantly greater in plots with a supplementary weed mulch than in other treatments. By contrast, spider density was greater when residue was piled or used as mulch rather than when scattered but the smallest populations occurred in the no-residue plots. Carabid beetles were significantly more abundant in plots with strips or piles of weeds and staphylinid beetles were most abundant in the mulched plots. Ants were not affected by weed residue placement. Among the ten pest groups studied, the abundance of only Chaetocnema sp., was significantly greater in plots with strips and piles than in other treatments, populations of other pests being unaffected by weed residue placement. In 1994, mean percentage of deadhearts (stem-borer damage) was significantly greater in the residue-free plots than in other treatments but in 1995 the differences between treatments were not significant. In both years, grain yield was not affected significantly by weed residue placement but was lowest in the residue-free plots.

Crop Losses Caused by Maize Stem Borers (Lepidoptera: Noctuidae, Pyralidae) in Côte da'Ivoire, Africa: Statistical Model Based on Damage Assessment During the Production Cycle

Eight insecticide experiments were conducted in 7 localities of Côte d'Ivoire to study the feasibility of developing a reliable model of crop losses of maize caused by stem borers based on damage assessment during the growing cycle. The observed damage was the percentage of tunneled internodes and the percentage of dead-hearts 80 d after seedling emergence. Five trials were used to fit the model; the remaining 3 were used to validate it. Sampling throughout the growing cycle revealed that only 2 borer species were involved: Busseola fusca (Fuller) (Lepidoptera: Noctuidae) and Eldana saccharina Walker (Lepidoptera: Pyralidae). Dead-hearts were mainly caused by the 1st species, whereas the tunneled internodes resulted from the presence of both pests. The model, which is aimed at estimating crop losses after damage has occurred, explained 81% of the variation in yield. The validation study showed that the model enabled a prediction of yield within a range of approximately ±10% at different localities and under different infestation conditions.