Stem Borer Population Research Articles

Weather based prediction model for rice yellow stem borer, (Scirpophaga incertulas Walker) under changing climate scenarios in Cauvery delta zone, Tamil Nadu

Aim: This research was carried out to identify the weather-based prediction model for rice yellow stem borer (YSB) population. The Stemborer incidence was recorded by using the light trap installed at TamilNadu Rice Research Institute (TRRI). The YSB data and climatological data of Aduthurai centre (Cauvery delta zone) from 2012 to 2022 were considered for this work. Methodology: The research methodology involved the conversion of daily light trap catch data into weekly data, which was then organized according to the Standard Meteorological Week (SMW) for model development. Three different predictive models were developed: Multiple Linear Regression (MLR), Stepwise Multiple Linear Regression (SMLR), and ARIMAX models. These models were used to forecast outcomes based on the weekly weather data and light trap catches. Results: The results indicated that the ARIMAX model demonstrated the lowest Root Mean Square Error (RMSE) when compared to both MLR and SMLR models, showing superior performance overall. Higher maximum and minimum temperatures negatively affected the YSB population, with decrease of 0.34 and 2.10 units per degree increase, respectively. Conversely, relative humidity had a positive effect, with an increase of 0.29 units per degree rise. This model underscores the significant influence of temperature and relative humidity on the population dynamics of stemborer. Interpretation: The model developed by using ARIMAX performed well than other models. It helps to conclude that weather parameters have can influence on pest population. Moreover, the models created in this research will significantly aid for monitoring and management purpose of the Yellow stem borer population in rice crop. Key words: ARIMAX, Oryza sativa, Rice yellow stem borer, Scirpophaga incertulas, Weather variables

Predictive modelling of yellow stem borer population in rice using light trap: A comparative study of MLP and LSTM networks

AbstractThe yellow stem borer (YSB), Scirpophaga incertulas (Walker), is a major insect pest that significantly damages rice crop. This study investigates methods to predict YSB populations in rice fields, aiming to develop an early warning system. Traditionally, rice farmers rely on light traps to monitor YSB presence. However, this study goes beyond this approach by combining light‐trap data with weather information (temperature, humidity, rainfall) and utilizing powerful artificial intelligence (AI) techniques to forecast future YSB populations. Two AI methods, multilayer perceptron (MLP) and long short‐term memory (LSTM), were employed to estimate YSB populations and assess their performance. The results revealed that the LSTM model outperformed the MLP model based on statistical metrics like RMSE, MAE, and R2 values. Utilizing LSTM model with historical data, stakeholders in the Eastern Coastal Plains and Hills agro‐climatic zone of India can gain a significant advantage in predicting YSB populations well in advance. This early warning system can alert stakeholders of potential YSB outbreaks, allowing them to take timely management actions and protect their rice crops from substantial yield losses.

Periodic colonization of Trichogramma japonicum for bio-control of yellow stem borer (Scirpophaga incertulas) in summer low-land rice (Oryza sativa)

Yellow stem borer [Scirpophaga incertulas (Walker)], is a major pest of low-land rice (Oryza sativa L.), causing 30–40% yield losses. The use of biological control agents to suppress yellow stem borer (YSB) population and damage across Asia includes inundative releases of the egg parasitoid, Trichogramma japonicum Ashmead. However, information on the time and number of parasitoids’ releases are lacking to control YSB in summer low-land rice. Therefore, an experiment was conducted during summer seasons of 2018 and 2019 at ICAR-National Institute of Biotic Stress Management, Raipur, Chhattisgarh to standardize the time and number of T. japonicum releases for effective biocontrol of YSB. Experiment consisted of 3 different treatment schedules, viz. T1, Four releases of T. japonicum at weekly intervals on the 7th, 14th, 21st, 28th days after planting (DAT); T2, Four releases of T. japonicum at weekly intervals on the 14th, 21st, 28th, 35th DAT; T3, Four releases of T. japonicum at weekly intervals on the 21st, 28th, 35th, 42nd DAT; and T4, Control (no release of wasps). Significant reduction of YSB-induced damage symptoms was observed in the treatment schedule (T2) consisting of four releases of T. japonicum (@50,000 wasps/ha/release) at weekly intervals on the 14th, 21st, 28th, 35th DAT of rice which significantly reduced the dead heart (9.1%, 45.83% reduction over control) and the white ear (1.8%, 47.05% reduction over control), as compared to untreated control plots (T4) (16.8% dead heart, 3.4% white ear) in summer 2018. Similarly, in summer 2019, the reduction in dead heart and white ear by the treatment (T2) was 43.35% and 46.15% over control, respectively. The significant reduction of YSB-induced damages corresponded with the increased grain yield in (T2) from 2018–19 i.e. 12.74–20.18% across the seasons. The results suggest that the (T2) augmentative releases provided ecologically viable bio-control of YSB during the summer seasons in low-land rice.

Efficacy of Different Concentrations of Insect Growth Regulators (IGRs) on Maize Stem Borer Infestation

Maize stem borer (Chilo Partellus), poses a substantial threat to maize crops all over the world, causing damage that ranges from 26.7% to 80.4%. Its destructive impact includes killing the shoot in young plants, leading to a “dead heart,” and damaging the upper stem in older plants through boring activity. To combat this issue, a field experiment evaluated various insect growth regulators (IGRs) such as Lufenuron®, Pyriproxyfen®, Sitara®, Viper®, Track®, and Priority®. These IGRs, known as reduced-risk pesticides, target pest juveniles and are less harmful to beneficial insects. Conducted through a Randomized Complete Block Design (RCBD) with 24 treatments, excluding a control group, the study recorded maize stem borer populations at 3, 7, and 14 days post-IGR application. In conclusion, the study identifies pyriproxyfen® and Priority® at double the standard concentrations as highly effective insect growth regulators in mitigating maize stem borer infestations, offering promising avenues for enhanced pest control strategies in maize cultivation.

First report and molecular identification of Chilo partellus (Swinhoe, 1885) in South-eastern Türkiye: invasion continues (Lepidoptera: Crambidae)

Chilo partellus (Swinhoe, 1885) (Lepidoptera: Crambidae), is an invasive maize pest that can cause high yield losses. The pest has recently been introduced and established in eastern Mediterranean countries such as Türkiye. However, research regarding its expansion towards other regions in Türkiye and other countries is required. This study is the first to report the presence and abundance of the pest in South-eastern Türkiye provinces, Diyarbakır, Mardin, Ranlıurfa, and Rırnak as well as the infestation rate and its contribution to the stemborer-dependent infestation rates. There were significant differences between the abundances of the pest in different counties, while the infestation rate, the contribution to the stemborer-dependent infestation rate, and the contribution to the total stemborer population were not statistically different between counties. The pest was only recorded in three southern counties of Ranlıurfa, during routine September surveys in 2022 and was absent in Diyarbakır, Mardin, and Rırnak. Specimens were morphologically diagnosed, and for molecular identification and phylogenetic analysis, nucleotide sequencing of the mitochondrial cytochrome oxidase subunit I (COI-I) gene was performed. All specimens were confirmed as C. partellus. Further, phylogenetic analysis revealed intraspecific genetic variation and the similarity of the specimens to reference sequences from Africa.

Population Fluctuations of Scirpophaga innotata and Nilaparvata lugens In Various Varieties and Growing Age of Rice Plants

Stem borer (Scirpophaga innotata) and brown planthopper (Nilaparvata lugens) are known as important pests in rice plants that attack plants from the nursery until just before harvest. Efforts to introduce new high-yielding varieties need to be carried out to provide farmers with references to varieties that are resistant or not to pest populations in the field. This study aims to look at the population levels of stem borer and brown planthopper pests at different planting ages for several test varieties. The method used was a randomized block design with 6 varietal treatments (IR14, IR15, IR16, IR18, IR19, IR20) and 3 tests with sampling intervals every week until 77 days after planting (HST). Data were analyzed using the Analysis of Variance (Anova) method and the Least Significant Difference Test (LSD). The results showed that the highest population of stem borers was found in plants aged 63 HST, namely 8 individuals/clump, while the lowest average population was found in plants aged 49 HST, namely 1 individual/clump. While the highest brown planthopper population was found at 77 HST, namely 10 individuals/clump, for the lowest population average at 63 HST, namely 4 individuals/clump. Populations of stem borer and brown planthopper in fact preferred rice variety IR14 with the highest population, while rice variety IR18 had the lowest population.

Modelling the Relationship between Weather Variables and Yellow Stem Borer Population: A Count Data Modelling Approach

Aim: This study was conducted to model the relationship between discrete dependent variable (yellow stem borer population) and continuous weather variables.
 Data Description: The yellow stem borer (YSB) population and standard meteorological week (SMW) wise weather variables (temperature, relative humidity, rainfall and sunshine hours) data of Warangal centre (Telangana state) generated under All India Co-Ordinated Rice Improvement Project (AICRIP) from 2013-2021 were considered for the study. The YSB population were recorded daily using light trap with an incandescent bulb and are counted as weekly cumulative catches.
 Methodology: The weekly cumulative trapped YSB populations and weekly averages of climatological data were considered as inputs to the models under consideration. In this study the classical linear regression i.e. step-wise multiple linear regression and count regression models such as Poisson, negative binomial, zero inflated Poisson and zero inflated negative binomial regression models were employed.
 Result: The empirical results revealed that the zero inflated count regression models viz., zero inflated Poisson regression and zero inflated negative binomial regression models performed better compared to the classical linear regression, Poisson and negative binomial regression models, further the negative binomial regression model outperformed all models as it yielded lowest mean square error (MSE) and highest R2 values. The average percentage reduction in accuracy of zero-inflated negative binomial regression model over classical model was around 4 percent.
 Conclusion: Based on the results obtained in this study, it is concluded that the zero inflated models performs better compared to classical models as they are unable to handle the presence of excess zeroes, as a result provides more prediction error and lower R2 values. Further, the models developed in this study will be of great assistance in identifying the factors influencing occurrence of YSB population in rice.

Biological performance of different Chilo partellus populations on diverse maize genotypes

Genetic variation within plants and herbivores influence the biological attributes and insect-plant interactions. We studied biological performance of different agro-ecological Chilo partellus (Swinhoe) populations on diverse maize genotypes during 2016-17 at ICAR-Indian Agricultural Research Institute, New Delhi. There was significant variation in larval period, larval survival, pupal period, pupal weight, and adult emergence of C. partellus populations on the test maize genotypes. Larval period of Hisar, and pupal periods of Hisar and Parbhani populations were significantly longer than other C. partellus populations across test maize genotypes. Pupal weight across maize genotypes was significantly higher in Delhi as compared to other populations. Larval survival and adult emergence were significantly higher in Delhi and Hisar, while lower in Raichur and Parbhani populations than other C. partellus populations across maize genotypes. Longer developmental periods, lower survival and adult emergence of C. partellus across populations on CPM 2 and CPM 8 indicate stable resistance in these maize genotypes against this pest. Higher survival in Hisar and Delhi populations across maize genotypes indicate their higher aggressiveness than other C. partellus populations. The differential resistance reaction, development and survival of different stem borer populations on diverse maize genotypes indicate the existence of different biotypes/ecotypes of C. partellus in India.

The effect of integrated pest management on Scirpophaga innotata population and natural enemies on rice field in South Sulawesi, Indonesia

Abstract. Rahmawasiah, Abadi AL, Mudjiono G, Rizali A. 2022. The effect of integrated pest management on Scirpophaga innotata population and natural enemies on rice field in South Sulawesi, Indonesia. Biodiversitas 23: 4510-4516. White rice stem borer, Scirpophaga innotata, is an important pest on rice plants that needs attention because the population is quite large in Luwu Raya. This pest attacks rice plants at all growth stages and can result in yield losses in rice production. Synthetic insecticides are a common control technique used by farmers to control these pests. The continuous use of pesticides will certainly have a negative impact. Therefore, pursuing effective control strategies and maintaining environmental sustainability is necessary. This study aimed to determine the white rice stem borer population and its natural enemies on rainfed land, and permanent irrigated lands managed conventionally and integrated pest management. The research was carried out using insect sampling techniques and calculating the white rice stem borer population and natural enemies in rice cultivation. In rainfed and irrigated rice fields, rice cultivation was carried out using conventional methods and integrated pest management (in the form of planting refugia and regulating the use of synthetic pesticides). The sampling was carried out on plants from the vegetative phase to the generative phase. The type of insect taken was the white rice stem borer in the form of collecting groups of eggs and larvae. Imago was observed visually and using a farmcop. In addition, the collection of natural enemy insects on the plantation was also carried out. The results showed that the application of the integrated pest management system caused no significant effect on the decline of the white rice stem borer population in both rainfed and permanently irrigated lands in Luwu Raya. The white rice stem borer population was more commonly found in rainfed land than permanently irrigated land. The parasitoids found were Telenomus rowani, Tetrastichus schoenobii and Trichogramma japonicum. The population of Telenomus rowani was more numerous than other types of parasitoids. On average, the parasitoid population was more in the land managed by integrated pest management (IPM) application than the conventionally managed land. The predators found on the land were Oxyopes javanus, Agriocnemis femina, Conocephalus longipennis, Menochilus sexmaculata, Ophionea nigrofasciata, Micraspis lineata, and Paederus fuscipes. Predator populations were more on land managed with the application of IPM than on land managed conventionally.

Review on bionomics and management of rice stem borer

Rice (Oryza sativa L.) is used as staple food for the overwhelming majority of the world’s population. Rice production hampered mostly by stem borers like, yellow stem borer (Scirpophaga incertulas) pink stem borer (Sesamia inference), dark headed stem borer (Chilo polychrysus), stripped stem borer (Chilo suppressalis). For minimize the infestation farmers use different resistant rice cultivars like, TKM 6, PTB 10, Su Yai 20, Mudgo, DV 139, Taitung 16, Gontra Bidhan 3, MTU-2020, IR 50, NDR-97, etc. against stem borer population. For controlling deleterious pest population farmers mostly use insecticide which exhibit good results than any botanicals against rice pests. Other techniques including using microbial pesticides, other biocontrol agents, use of pheromones or allomones, staggered planting, synchronized planting, removal of infected leaves, steams with pruning shears, using of trap crop, etc. are effective for control rice pests. But indiscriminate use of chemical insecticides results in great economic loss with destabilizing of biodiversity and resulting cross resistance against insecticides. So, pest population ecology based sustainable management strategies of such pest species is very essential for climate smart pest management (CSPM) as well as climate smart agriculture (CSA) of rice and other crops in the near future.

Incidence and relative abundance of rice stem borers in three selected rice fields in Lagos and Ogun States, Nigeria

This study was conducted to investigate the incidence of rice stem borer infestations and the species composition present in the selected rice fields. Data were collected between April 2017 and November 2018 across three locations, which include the upland rice field in Agbajege, Ogun state, rainfed lowland in Itoikin and Mangrove swamp in Igbogun, Lagos state, respectively. The incidence of rice stem borers was indicated by dead heart and white heads symptoms, while tillers were excised for rice stem borer identification and population. Results showed a high and low incidence of rice stem borers with no significant difference(p>0.05) at p= 0.29 and 0.37 between the early and late planting seasons in the rainfed lowland and upland rice fields respectively. Planting seasons were significant in the incidence of rice stem borers in mangrove swamp rice fields at p<0.05, p=0.01). This study showed that the predominant species of rice stem borers present in the three study sites were Chilo zacconius and Sesamia calamistis. C. zacconius was the most abundant species at 89% while S. calamistis was 11%. Rice stem borer populations were significantly higher at (p<0.05, p=0.000) in flooded zones while the highest rice stem borer populations were observed at the reproductive phase of the rice plants. Thisstudy showed that the planting seasons coincided with the peak period of the development of rice stem borers. Hence, conservation of natural enemies, monitoring and surveillance should be adopted in insect pest management in rice agroecosystems

Influence of abiotic factors on stem borer incidence and species distribution in rice (Oryza sativa L.)

Aim: To evaluate the effect of abiotic factors such as temperature, relative humidity, wind velocity, sunshine hours and rainfall on the distribution and relative abundance of stem borer species in rice ecosystem. Methodology: Seasonal incidence of stem borer species was monitored using light trap catches and were correlated with the weather parameters. The relative abundance of stem borer species during Kharif and Rabi was estimated based on light trap catches and larval incidence. Results: Seasonal incidence revealed the occurrence of three stem borer species (yellow stem borer, pink stem borer and dark headed borer) populations in rice ecosystem. Yellow stem borer was found to dominate in rice ecosystem during Kharif, (80.61%) whereas during Rabi, pinkstem borer was found to be dominant (72.60%) than yellow stem borer (21.92%) and dark headed borer (5.48%). Weather parameters such as temperature, rainfall and wind velocity negatively influenced the occurrence of stem borer species in rice, whereas relative humidity and sunshine hours had positive effect. Regression analysis revealed the increased effect of abiotic factors such as temperature, relative humidity and wind velocityon the population of pink stem borer against yellow stem borer and dark headed borer. Interpretation: The present study reveals that, the change in weather parameter during seasons, such as temperature (25 - 27°C), relative humidity (69 - 80 %) and wind velocity (3 - 4 km hr-1) increased the fitness of pink stem borer species population than yellow stem borer and dark headed borer species in rice ecosystem, which was evidenced by the occurrence and relative abundance of pink stem borer population during Kharif 2018 and Rabi 2019 respectively.

Komposisi Spesies Penggerek Batang Padi dan Parasitoid Telurnya pada Ketinggian Tempat yang Berbeda

Composition of Rice Stem Borer Species and Their Egg Parasitoids at Different Altitudes. Rice stem borer is one of the main pest of rice plants that always percolating and attack plants in the field. The pests can result in damage to plants and lost of the grain from season to season. The aim of this research is to know composition and dominance rice stem borer species and role of their eggs parasitoid at an altitude of different places. Research is done by survey based on the height of different altitude in rice plants two weeks after cropping up until eleven weeks after planting. Research conducted from April until August 2019 in rice field that belonging to farmers at Subak Cemagi Let, Cemagi Village and Subak Teba, Mengwi village, Badung regency, Bali province. Subak Cemagi Let are at an altitude of 15 meters above sea level whereas Subak Teba are at an altitude of 300 meters above sea level. Identification of Rice stem borer larvae and their eggs parasitoid done in Pest Laboratory, Agriculture Faculty of Udayana University. Found three species rice stem borer in the height 15 mdpl namely Scirpophaga incertulas; Sesamia inferens dan Chilo suppressalis, whereas in the height 300 mdpl found four species namely Scirpophaga incertulas, Sesamia inferens, Chilo suppressalis, dan Chilo polychrysus. S. incertulas was the most dominant at the two different altitude. Three species of eggs parasitoid that have role to suppress the development of rice stem borer at the different altitude namely Tetrastichus schoenobii, Telenomus rowani dan Trichogramma japonicum. T. schoenobii was the most dominant to suppress rice stem borer populations.

Effectiveness Test of Parasitization by Parasitoid Tricogramma japonicum in Controlling White Rice Stem Borer (Scirphopaga innotata)

Rice is an essential food crop besides corn and soybeans. The need for rice each year increases along with population growth. One of the pests affecting rice is the white rice stem borer. The present research aimed to test the effectiveness and to examine the interaction between plant age and the number of Tricogramma japonicum parasitoid. The research was carried out at the Agrotechnology Laboratory of the Faculty of Agriculture, Khairun University, Ternate, and the rice fields of Bumi Restu village SP I, East Wasile district. The research design operative was a randomized block design where factor A (A1 = 21 DAS, A2 = 42 DAS, A3 = 56 DAS) was the age of the plant, and factor B (B0 = 0, B1 = 50, B2 = 100, B3 = 150) was the number of eggs of Corcyra cephalonica. Biological control using different amounts of Trichogramma japonicum parasitoid led to different interactions and results for each tested parameter. For the number of egg groups, there was no interaction with plant age, but the treatments which were found effective in suppressing stem borer populations were B2 and B3 (100 and 150). The most effective pias as indicated by damage intensity parameter was B3 (150), which was applied to plants aged 21 DAP. Furthermore, for plant height, different number of parasitoids poses significantly effective results. Percentage unhulled grain of pias B3 (150) causes insignificant damage. For production there is no interaction with plant age, but pias B2 (100) shows high yield. The conclusion is that pias B3 (150) applied to 21 days of plants is very effective in controlling white rice stem borer.

Do parasitoids reduce cereal losses? Estimating the impact of parasitoids on stem borer pest infestation and maize yield

Chilo partellus (spotted stem borer) is an economically important stem borer pest in Eastern Africa causing high yield losses in maize and sorghum. The larval endoparasitoid, Cotesia flavipes (parasitic wasp) was released in Kenya to manage C. partellus and post release studies showed it had established and stem borer parasitism was steadily increasing. Despite the rise in parasitism, doubts on whether parasitoids can effectively reduce stem borer populations have been raised.Objective: This study was carried out to estimate the impact of C. flavipes on stem borer infestation and the resultant effect on maize yield in Kenya. Methodology and results: Using insecticidal check method, selective insecticides were used to exclude stem borer pests and natural enemies in Treatments A and B respectively with controls designated as Treatment C. Results revealed significant differences in stem borer infestation (F2,9=5.835; p<0.05) and parasitism (F2,9 =91.97; p<0.0001) among the three treatments. Significantly higher infestation was recorded in treatment B (2.0±0.2%) compared to A (0.5±0.3%) and C (1.5±0.4%). Parasitism was significantly higher in treatment C (23.5±6.8%) compared to A (0.0±0.0%) and B (0.3±0.1%). However, there was no significant difference in yield among treatments showing that parasitoid action did not translate into changes in yield. Conclusions and application of findings: The parasitoid C. flavipes has made an important contribution towards suppressing stem borer population. This was shown by high infestation recorded in treatment B which was as a result of partial elimination of parasitoids. This deduction was further supported by the results which showed that pest exclusion using chemicals did not have a significant difference from parasitoid action as shown by insignificant difference in infestation between treatment A and C fields. Percentage infestation and parasitism results obtained from this study thus provide quantitative data on the impact of C. flavipes. Release of C. flavipes can therefore be done in other areas both within and beyond the country’s borders where C. partellus is still a problem. However, since reduced infestation and increased parasitism did not translate into yield increase, more suppressive effect may be achieved if the pest’s multiple developmental stages are targeted, most especially before it reaches the destructive larval stage. There is need to carry out further research on C. partellus’ egg parasitoids. Optimum yield may then be realized.Key words: Classical biological control; Chilo partellus ; Cotesia flavipes; parasitism; insecticidal check technique; Kenya

Impact of crop establishment methods on rice insect pests incidence in Indo Gangetic Plain (IGP)

Rice (Oryza sativa L.), is the staple food for more than half of the world population and an important target to secure food security and livelihoods for millions. The production of rice to mitigate the consumption requirement needs huge amount of water. Direct seeded rice (DSR) technique is becoming popular nowadays because of its lowinput demands and potential to maximize the water productivity under deficit soil moisture. Rice variety, Pusa 1121 is important variety in major rice growing areas of Indo Gangetic Plain that occupies more than 70% area. The population of planthoppers and stem borers were significantly higher and appeared early in direct seeding crop as compared with transplanted rice (TPR). The mean seasonal incidence of stem borers in 2014 were 9.58 and 5.29% in direct seeding whereas in 2015 it was 9.36 and 4.97%. The damage (white ears) was observed maximum on 42nd week in October. The result revealed that incidence of leaffolder was significantly higher in direct seeding than transplanting. The population/ incidence of pests showed positively significant correlation with biotic factors during the study. The grain yield in transplanting crop was also significantly higher than direct seeding. So, management practices in direct seeding should be practiced earlier as compared to transplanted rice to maximize yield by reducing pest population pressure for sustainable agriculture and to conserve natural resources.

Study of Paddy Stem Borers Population Dynamics and Influencing Environmental Factors through Light Trap

Rice crop is affected by many insect pests like White Stem Borer, Yellow Stem Borer and Pink Stem Borer. Rice stem borers are main pests affecting rice crop from nursery to physiological maturity including them in key pests. These studies had been carried out to discover the encouraging and antagonistic boundaries of weather parameters for the rice stem borers. As per result of studies, the population was recorded higher from mid-March to 1st week of May and then it escalated again from 2nd week of August to a maximum in September in case of Yellow Stem Borer (Scirpophaga incertulus) and White Stem Borer (Scirpophaga innotata) of rice during the both years 2017-2018; while in case of Pink Stem Borer population recorded from mid-September to the last week of April in 2017 and lasted till 4th week of May 2018. On evaluating the weather conditions specially temperature and relative humidity, it was detected that insect trap catches noted inside a certain range of temperature that varies from 18-35°C in case of White Stem Borer and 17-34°C for Yellow stem borer of rice. Extreme catches were documented in April and September inside a temperature range of 26-32°C considering it ideal series of temperature for insect light trap catches and activity of yellow and white stem borer. However, in case of pink stem borer above 32°C no catch was observed.

Abundance of arthropod insect pests and natural enemies in rice field as influenced by rice growth stages and neighboring crops

Studies were conducted to record the abundance of arthropod insect pests and natural enemies in rice fields as influenced by rice growth stages and neighboring crops at the experimental farm of Patuakhali Science and Technology University (PSTU), Dumki, Patuakhali during 2012 in Boro rice season following randomized complete block design. Results indicated that rice-tree habitat showed the highest abundance of leafhoppers (100.75) followed by cricket (16.50), grasshoppers (15.25) and stink bugs (15.25). The lowest abundance of all insect pests was in rice-sesame habitat. No significant differences were found on the abundance of rice bug, rice hispa and stem borer populations. At seedling stage, the highest abundance of leafhopper (94.25) was recorded followed by grasshopper (47.00) and stink bug (26.50) while the lowest was stem borer (0.57) and rice hispa (6.00). At early tillering stage, maximum number of grasshopper (17.25) was recorded followed by cricket (7.00). At maximum tillering stage, the highest abundance of leafhoppers (122.5) was obtained followed by rice bug (62.00) and the lowest was the stink bug (7.00). At panical initiation stage, the highest abundance of rice bug (334.00) was recorded which was followed by leafhoppers (65.25) and the lowest was the cricket (15.75). No population of rice hispa and stem borer was recorded at maximum tillering and panical initiation stages. In case of natural enemies, the highest abundance of lady bird beetle (45.27) and damselfly (16.73) was found in rice-rice habitat. The highest abundance of ichneumonid wasp (57.53) was in rice-tree habitat and ground beetle (28.80) was in rice-sesame habitat. No significant differences were observed on the abundance of dragonfly, spider and dipteran fly among different habitats. Among different growth stages of rice plant, significantly the highest abundance of lady bird beetle was recorded at maximum tillering stage. The highest abundance of ichneumonid wasp and ground beetle was recorded at seedling stage. The highest abundance of damselfly, spider and dipteran fly was at early tillering stage. No significant difference was observed on the abundance of dragonfly among different rice growth stages.Bangladesh J. Agril. Res. 42(2): 309-319, June 2017

Predictive Modeling of Rice Yellow Stem Borer Population Dynamics under Climate Change Scenarios in Indramayu

Rice Yellow Stem Borer (YSB) is one of the major insect pests in rice plants that has high attack intensity in rice production center areas, especially in West Java. This pest is consider as holometabola insects that causes rice damage in the vegetative phase (deadheart) as well as generative phase (whitehead). Climatic factor is one of the environmental factors influence the pattern of dynamics population. The purpose of this study was to develop a predictive modeling of YSB pest dynamics population under climate change scenarios (2016-2035 period) using Dymex Model in Indramayu area, West Java. YSB modeling required two main components, namely climate parameters and YSB development lower threshold of temperature (To) to describe YSB life cycle in every phase. Calibration and validation test of models showed the coefficient of determination (R2) between the predicted results and observations of the study area were 0.74 and 0.88 respectively, which was able to illustrate the development, mortality, transfer of individuals from one stage to the next life also fecundity and YSB reproduction. On baseline climate condition, there was a tendency of population abundance peak (outbreak) occured when a change of rainfall intensity in the rainy season transition to dry season or the opposite conditions was happen. In both of application of climate change scenarios, the model outputs were generated well and able to predict the pattern of YSB population dynamics with a the increasing trend of specific population numbers, generation numbers per season and also shifting pattern of populations abundance peak in the future climatic conditions. These results can be adopted as a tool to predict outbreak and to give early warning to control YSB pest more effectively.

Different IGRs concentrations against maize stem borer (Chilo partellus Swinhoe) in field condition of Faisalabad-Pakistan

The experiment was conducted at the Youngwala experimental area of the Department of Agri. Entomology, University of Agriculture, Faisalabad in a Randomized Complete Block Design (RCBD), with 24 treatments excluding one control. The data for maize stem borer population was recorded after 3 days, 7 days and 14 days post IGRs application. The results obtained are concluded that all the insect growth regulators were equally effective against maize stem borer at different concentrations and on the numerical basis lowest stem borer population and its infestation was recorded in the pyriproxyfen® and priority® at 2x concentration and at concentration of field recommended concentration followed by other treatments concentrations. So, among the entire tested insect growth regulators pyriproxyfen® and priority® were the most effective IGRs against maize borer. Among the entire tested insect growth regulators viper® and sitara® were the least effective IGRs against maize borer.