Leptocorisa Acuta Research Articles

Bionomics of Earhead Bug Leptocorisa acuta Thunberg (Coreidae: Hemiptera) Infesting Rice

Biology of rice earhead bug, Leptocorisa acuta (Thunberg) carried out at Laboratory of Department of Entomology, N. M. College of Agriculture, Navsari Agricultural University, Navsari, Gujarat on rice (Gujarat Rice-11) during kharif-2023. Eggs were dark brown with an average length and breadth of 1.28±0.05 mm and 0.85±0.06 mm, respectively. The incubation period varied from 5 to 7 days with an average of 6.07±0.78 days and the average hatching percentage was 81.22±14.93 per cent. There were five nymphal instars in the life cycle of L. acuta. The average developmental periods of the first, second, third, fourth and fifth nymphal instars were 2.80±0.41, 1.67±0.55, 1.87±0.57, 2.83±0.53 and 4.23±0.63 days, respectively. The total nymphal period was an average of 13.77±0.86 days. The total developmental period (egg + nymph) was found to be an average of 19.83±1.39 days. The average adult period was 23.50±7.69 days. The average pre-oviposition, oviposition and post-oviposition periods lasted for 4.87±1.50, 9.03±3.36 and 15.63±3.20 days, respectively. The average longevity for male and female adults lasted for 17.47±2.83 and 29.53±3.91 days, respectively. The female laid an average of 53.96±31.90 eggs. The total life cycle from egg to adult was an average of 42.67±7.38 days.

Study of Seasonal Incidence of Rice Earhead Bug (Coreidae: Hemiptera)

This study investigates the relationship between climatic factors and the population dynamics of the rice earhead bug (Leptocorisa acuta) in Balaghat district of Madhya Pradesh. Through correlational analysis, we examined the associations between rainfall, rainy days, morning relative humidity (RH), evening RH, evening vapour pressure, wind velocity, maximum temperature, morning vapour pressure, evaporation, sunshine, and the prevalence of rice earhead bugs. Results indicate a negative correlation between rice earhead bug population and both rainfall and rainy days, suggesting a potential suppression effect of increased precipitation on bug abundance. Morning RH, evening RH, evening vapour pressure, and wind velocity showed non-significant negative correlations with bug population, indicating that these factors may have limited influence on bug dynamics in our study area. Conversely, a positive non-significant correlation was observed between rice earhead bug population and maximum temperature, morning vapour pressure, evaporation, and sunshine. This implies that higher temperatures and increased solar radiation may have a subtle positive effect on bug abundance, although further investigation is warranted to elucidate the underlying mechanisms. Overall, our findings shed light on the complex interplay between climatic factors and rice earhead bug dynamics, highlighting the importance of considering multiple variables in pest management strategies for rice cultivation.

Study on Major Disease-insect Incidence of Scented Gobindabhog Rice in New Alluvial Zone of West Bengal

A comprehensive study on “Improvement of production and storage system for Gobindabhog rice in West Bengal,” comprising two field and one laboratory experiment, was done at Bidhan Chandra Krishi Viswavidyalaya, Kalyani, Nadia, West Bengal, India, during the period of 2010–2012 to find out the optimum planting time, spacing, nutrients, disease, and pest management for scented Gobindabhog rice during the kharif season. Plant height, tiller production, and leaf area index increased consistently with the advancement of crop growth up to panicle exertion, panicle initiation (i.e., 56 DAT), and flowering (i.e., 84 DAT) stages, respectively. The planting date had a significant effect on the incidence of blast disease in Gobindabhog rice during both 2010 and 2011, except at 28 DAT. Delay in planting generally provided a favorable environment for the causal organism (Payricularia oryzae) during the vegetative and reproductive stages of Gobindabhog rice, thereby leading to a greater incidence of delayed crops (25 July, 10 August, and 25 August) than the earlier one (10 July). The susceptibility of the Gobindabhog rice crop to brown spot disease caused by Drechslera oryzae increased progressively with the advancement of crop age from 28 DAT (i.e., active tillering stage) to 84 DAT (i.e., flowering stage). The population of gundhi bug (Leptocorisa acuta) increased steadily from 84 DAT (i.e., 50% flowering) to 112 DAT (maturity stage), irrespective of main and sub-plot treatments as well as years of investigation.

Incidence and Population Dynamics of Various Associated Insect-pests of Late Direct Sown Paddy, Oryza sativa L. at Gajapati, Odisha

Background: Rice is the most important staple food of the world. Rice production is now-a-days reduced due to insect pest attacking to the crop in various growing stages. There are more than 1400 pest species, which are cause great menace to the rice cultivation. Incidences and abundance of pests in rice is growing day by day due to climatic change and excess use of chemical pesticides. In late direct sown paddy is also facing the insect pest problems in different growing stages. The study aimed to layout the different pest’s incidence and population dynamics as well, on various stages of direct sown paddy. The knowledge of incidence timing for various pests can be further utilized for the suitable management. Methods: The present study has been conducted during the late Kharif seasons of 2021-22 for 11 most widely grown paddy cultivars of farmers field around the locality of MS Swaminathan School of Agriculture, Centurion University of Technology and Management, Paralakhemundi, Odisha. The surveyed cultivars were Anjali, Arize 8433, BAM-6, Bhuban, Chandra, CR Dhan 100, Varsha Dhan, CR Dhan 306, Sumit, Luna Sankhi and Vandana, respectively. These cultivars were surveyed for the abundance of various associated insect-pests at two different crop growth stages. Result: The results revealed that the incidence of various pests namely Scirpophaga incertulus, Orseolia oryzae, Cnaphalocrocis medinalis, Parapoynx stagnalis, Dicladispa armigera, Leptocorisa acuta, Grasshoppers, Nezara virdula, Nephotettix virescens, Melantis leda and Mythimna separate was found to be significant for both the growth stages. The maximum population on late direct sown rice was found to be of Scirpophaga incertulus (3.67) and Orseolia oryzae (2.67) at the vegetative stage of rice while pests such as Cnaphalocrocis medinalis (6.34), Leptocorisa acuta (7.34) and Mythimna separate (5.67) were recorded maximum during the milking stage of rice.

Application of Various Concentrations of Mixed Extracts of Calotropis gigantea and Crescentia cujete Against Population and Attack Intensity of Leptocorisa acuta, Nephotettix virescens and Natural Enemy Populations of Rice Plants

Changes in land and pesticide are the main drivers of changes in the biodiversity of agricultural land, particularly natural enemies of insect pests. Leptocorisa acuta and Nephotettix virescens are the main pests of rice plants in Indonesia which are mostly controlled with pesticides. The use of extracts of natural ingredients Calontropis gigantea leaves and Crescentia cujete fruit is an alternative for controlling rice pests. The purpose of the study was to determine the mixed extracts of C. gigantea and C. cujete with various concentrations on the population and the attack intensity of Leptocorisa acuta and Nephotettix virescens as well as natural enemies population. This study consisted of six treatments, namely a concentration of 1%; 2.5%; 4%; 5.5%; 7% and farmer treatment. Observations were made visually and sweep net by taking samples diagonally in one plot was taken five plant sample points were and in one point consisted of four clumps of rice. The results showed that, in comparison to the farmers treatment, the population and attack intensity were low for all extract concentration treatments, and statistical analysis did not reveal any statistically significant differences between concentrations. In comparison to farmer treatment, the population of natural enemies was high in all extract treatments. When mixed extracts of C. gigantea and C. cujete are used for pest management of rice plants, the number and severity of pest attacks can be reduced without affecting natural enemies.

Production of Lemongrass Extract to Control the Stink Bugs (Leptocorisa acuta L.) in Babatan Village, Lintang Kanan District

The use of chemical pesticides in controlling pests is still widely used by some farming communities in Babatan Village, Lintang Kanan District, Empat Lawang Regency. Improved use of chemical pesticides hurts agricultural production and the environment. One alternative to chemical pesticides is plant-based pesticides which are safer and more environmentally friendly in supporting the implementation of integrated pest control (IPM). The results of a field survey in Babatan Village show that many plants can be used as vegetable pesticides, such as citronella (Cymbopogon sp) as a substitute for chemical pesticides. This counseling activity aims to introduce the benefits and methods of making lemongrass extract to control the pest stink bugs (Leptocorisa acuta L.) which attack many rice plants in Babatan Village. Implementation of activities on 4-5 February 2022 with the target targeting members of the Makmur Jaya Farmer Group. This community service activity uses counseling methods (lectures and discussions), demonstrations, and evaluations. The results of this activity indicate that the members of the Makmur Jaya Farmer Group, Babatan Village, Lintang Kanan District, Empat Lawang Regency gave a good response, can understand, and will apply the method of making and using the lemon grass plant pesticide in suppressing the stink bugs pest population so that the cost of buying chemical pesticides can be reduced, produce healthy plants, no residue that pollutes the product and the environment, and sustainably increases production.

Abundance of Major Insect Pests in Rice and Their Relation to Weather Parameters

The present investigation has been conducted in rice crop during Kharif 2021-22at Students’ Instructional Farm of Acharya Narendra Deva University of Agriculture and Technology, Kumarganj, Ayodhya (U.P.), India. The population of six major insect pests was recorded viz. Rice Yellow stem borer (Scirpophaga incertulus), Rice Leaf folder (Cnapholocrocis medinalis), Rice ear head bug (Leptocorisa acuta), Brown plant hopper (Nilaparvata lugens), White backed plant hopper (Sogatella furcifera)and Green leaf hopper (Nephotettix nigropictus) that cause most damage at different crop growth stages initiated after sowing till harvesting. The maximum population of yellow stemborer was observed on rice crop at 36th SMW (12.20 per cent dead heart). The infestation of dead heart was non-significant positively correlated with minimum, maximum temperature and RH% (0.433, 0.010 & 0.253 respectively) and negatively correlated with rain fall (0.081) whereas, significant negatively correlated with sunshine (0.552*). The maximum population white ear in 40th SMW (16.80 per cent). The infestation of white ear was non-significant negative correlation with minimum, maximum temperature (-0.062, -0.167) and positive correlation with RH & rain fall (0.244 & 0.173) whereas, significant positive correlation with sunshine (0.703*). Maximum leaf folder population was observed during 35th SMW (16.35 per cent). and infestation of leaf folder was non-significant positive correlation with minimum temperature & RH (0.427 & 0.505) and negative correlation with maximum temperature, rainfall and sunshine (-0.079, -0.030 & -0.291). The maximum population was recorded of ear head bug in 38th SMW i.e., (10.90 ear head bug/hill respectively.). The infestation of ear head bug was non-significant positive correlation with minimum temperature, RH, rainfall & sunshine (0.061, 0.176, 0.155 & 0.210) and negative correlation with maximum temperature (-0.407). The peak mean population of BPH was recorded in 37th SMW i.e., (11.25 brown plant hopper/hill respectively.) Itwas non-significant positive correlation with minimum temperature & RH (0.463 & 0.357) and negative correlation with maximum temperature & rainfall (-0.066 & -0.088) whereas, significant negative correlation with sunshine (-0.597*), The peak mean population of WBPH was recorded in 38th SMW i.e., (12.80 white backed plant hopper/hill respectively.) It was non-significant positive correlation with minimum temperature, RH & rainfall (0.300, 0.337 & 0.185) and negative correlation with maximum temperature (-0.300) whereas, significant negative correlation with sunshine (-0.094*) and the maximum population of green leaf hopper was recorded in 37th SMW i.e., (10.80 green leaf hopper/hill respectively.) with the infestation of green leaf hopperwas non-significant positive correlation with minimum temperature & RH (0.479 & 0.369) and negative correlation with maximum temperature & rainfall (-0.077 & -0.120) whereas, significant negative correlation with sunshine (-0.633*).

Effect of dose of NPK fertilizer on attack intensity of Leptocorisa acuta and lowland rice production

Rice is a strategic commodity for Indonesia. NPK fertilizer is a compound fertilizer with fast absorption, accelerates flowering, fruiting, flowering process and stimulates shoot growth. The pest that often attacks rice is Leptocorisa acuta which sucks the grain in the ripening phase and sucks the grain until it is empty or filling is not full, resulting in a decrease in production. This study used a non-factorial Randomized Block Design with 8 replications and 3 treatments of NPK fertilizer doses which included NPK P1 fertilizer: 100 kg/ha; P2: 200 kg/ha NPK fertilizer and P3: 300 kg/ha NPK fertilizer. The results showed that the application of several doses of NPK fertilizer had no significant effect on the intensity of L. acuta attack due to an increase in population. The highest population of L. acuta was found in the application of 100 kg/ha NPK fertilizer with an average of 17.50 individuals. The increase in new individuals is influenced by the availability of feed and pest control is not carried out. The application of several doses of NPK fertilizer did not significantly affect rice production, due to the high intensity of L. acuta attack which caused a decrease in rice production.

Susceptibility of Egg Stadia of Walang Sangit (Leptocorisa acuta thunb.) To Entomopathogenic Fungi Beauveria Bassiana (bals.) Vuill. and Metarhizium spp. From various rhizosphere

This study aims to determine the pathogenicity of the entomopathogenic fungi Beauveria bassiana (Bals.) Vuill and Metarhizium spp. isolated from various locations. against Walang Sangit (Leptocorisa acuta Thunb.) eggs. In this experiment, the egg group of Leptocorisa acuta and 5 isolates of entomopathogenic fungi were used, namely Bb5a, Bb4b, Bb1e, Met3b, and Met1a. Application of entomopathogenic fungi was carried out by spraying entomopathogenic fungi according to the treatment using hand sprayer in each treatment as much as 2 ml. Conidial concentration of each isolate used for testing was 108 conidia/ml. The variables observed were L. acuta egg mortality, 1st instar L. acuta nymph mortality, and length of 1st instar L. acuta nymph death. Observational data were analyzed statistically by Analysis of Variance (Anova), if it had a significant effect then it was continued with the DNMRT test at 5% level. The results showed that isolates of entomopathogenic fungi Bb4b and Met3b had a significant effect on L. acuta egg mortality, 1 L instar nymph mortality .acuta, and time of death of 1st instar nymph L.acuta.

Efficacy of different insecticides and biopesticides against gundhi bug (Leptocorisa acuta Thunberg) on rice (Oryza Sativa L.)

Efficacy of different insecticides and biopesticides against gundhi bug (Leptocorisa acuta Thunberg) on rice (Oryza Sativa L.)

IDENTIFIKASI TINGKAT KESEHATAN PADI SAWAH DI KECAMATAN KONDA KABUPATEN KONAWE SELATAN AKIBAT SERANGAN HAMA

Rice (Oryza sativa L.) is an important food crop in developing countries including Indonesia. Lowland rice cultivation has problems in the field, especially the level of plant health. The level of plant health is determined by the disturbance and intensity of pest attacks. This study aims to determine the types of pests of lowland rice, the intensity of pest attacks and the health level of paddy rice plants. The research was conducted in the villages of Puosu Jaya, Lamomea Village and Lebo Jaya, Konda District, Konawe Selatan Regency and the Plant Protection Laboratory of the Entomology Unit, Faculty of Agriculture, Halu Oleo University Kendari. The research was conducted from October to December 2021. The variables observed were types of rice pests, intensity of damage and health level of paddy rice plants. This research uses descriptive analysis. Pests that attack paddy rice in Konda District, South Konawe Regency consist of Scirpophaga innotata, Cnaphalocrocis medinalis, Locusta migratoria, Leptocorisa acuta and Rattus argentiventer. The health level of lowland rice in Konda District, Konawe Regency due to attacks is classified as moderate to good.

Laboratory Assessment of Role of Epicuticular Waxes of Two Endemic Rice Cultivars in Attraction and Oviposition by the Insect Bug Leptocorisa acuta (Hemiptera: Alydidae)

Laboratory Assessment of Role of Epicuticular Waxes of Two Endemic Rice Cultivars in Attraction and Oviposition by the Insect Bug Leptocorisa acuta (Hemiptera: Alydidae)

Main and Ratooned Rice Pest Populations in Lowland Rice Fields, South Sumatra Applied Bioinsecticide from Entomopathogens

The pests that attack each plant phase also varies. The aimed of this study was to compare the main population of rice insect pests and ratooned in lowland rice field in the vegetative, flowering and milk ripening phase. The main bioinsecticide rice sprayed on rice canopy were comes from the entomopathogenic fungal conidia Metarhizium anisopliae, the entomopathogenic bacterium Bacillus thuringiensis, and as a control area without the application of bioinsecticide or synthetic insecticide. The results showed that population of fake white pests (Cnaphalocrosis medinalis) and white leafhoppers pest (Covana spectra) were more prevalent in vegetative phase rice compared to other types of pests such as green leafhoppers (Nephotettix spp.), Brown leafhoppers (Nilaparvata lugens), zig zag leafhoppers. (Recillia dorsalis), white-back leafhoppers (Sogatella furcifera), grasshoppers, mole cricket (Gryllotalpa gryllotalpa), and yellow rice stem borer (Scirpophaga incertulas). The Leptocorisa acuta and green ladybugs (Nezara viridula) began to attack the flowering and milk ripening phase, which was when the rice was aged about 54-68 days after transplanting (dat). Whereas in ratooned rice, the pest population of L. acuta has appeared on the first observation on rice aged 9 days after harvest (dah) until the ratooned rice was aged 58 days after harvesting. The population of pests was higher in land without bioinsecticide application compared to land applied of bioinsecticides. In ratooned rice, the pest population between the land applied with bioinsecticide M. anisopliae and B. thuringiensis was not significantly different from the land applied by B. thuringiensis which was sold in the market.

Biodiversity And Arthropod Abundance In Organic Semi Rice In Swamp Lowland in Palangka Raya City

Palangka Raya has the potential for swamp lowland to be used for rice farming. For this purpose, knowledge of arthropod biodiversity is required. The study aims to determine the biodiversity and abundance of arthropods and arthropods dominant in semi-organic rice plantations in swamp lowlands. The study was conducted from September to November 2019 in Palangka Raya City. The study was carried out on 1.148m2 farmer's paddy fields. The land is divided into three trial plots, each measuring 28x13 m2. Observations were made at the age of 8-15 WAP. Samples were taken using a net trap (Sweep net). Arthropod biodiversity was analyzed using the Shannon-Weaver diversity index (H'). The results showed that in the semi-organic rice ecosystem were obtained 10 orders, 58 families with a total of 8973 individuals, consisting of pests 92.61%, predators 6.59%, parasitoids 0.28%, pollinators 0.06%, Detrivore 0.35%, and 0.07% neutral insects. Diversity index (H') is low to moderate (0.10-2.19), dominance index (C) is in the low to high (0.18-0.97); Evenness index shows that the community is depressed until unstable (0.04-0.67); and The abundance index on the criteria of less to very much (8.96-25.03). The dominant arthropods are dominated by the Rice bug (Leptocorisa acuta).

Species delimitation of rice seed bugs complex: Insights from mitochondrial genomes and ddRAD‐seq data

AbstractSpecies delimitation is very important for the study of taxonomy and is essential for pest control and management. Our study focussed on the species delimitation of five Leptocorisa species (Insecta: Hemiptera: Alydidae: Leptocorisa) from China, especially for the rice seed bugs (Leptocorisa acuta species complex) due to their extreme morphological similarities. We applied multifarious distance‐based and tree‐based methods for species delimitation in the L. acuta species complex based on the multilocus genetic markers (i.e. cytochrome oxidase subunit I (cox1), whole mitochondrial genomes (WMGs) and double‐digest restriction site‐associated DNA sequencing (ddRADseq)). Both cox1 and WMGs failed to distinguish the two recent divergent taxa in the L. acuta species complex (L. chinensis and L. oratoria). However, genome‐wide nuclear SNP data unambiguously identify two separate species, which were congruent with the morphological species assignments. In addition, the morphological characters used for identification are diagnostic and stable. For the observed mito‐nuclear discordance pattern between L. chinensis and L. oratoria, mitochondrial introgression resulting from hybridization was probably inferred as the most likely explanation, which needed to expand the sampling range of the two species for further analysis. This study first provided molecular evidence for the delimitation of rice seed bugs complex, which was essential for further studies of ecology and pest management of these important rice pests.

Application of the flower of Beauveria bassiana Through immersion Seeds and It's effect on Colonization and content of Chlorophil leaves of red chilli (Capsicum annuum L.)

Endophytic fungi in lately was getting a lot of attention in agriculture. Besides being able to increase plant resistance against plant pest organism, it has also the ability to stimulate germination and pant growth. One of endophytic fungi tested in its research was Beauveria bassiana from isolate Wheat, Coffeae, Cacao and entomopatogen fungus from Leptocorisa acuta insect. The aim of this research was to know the ability of Beauveria bassiana from some tested isolates and its effect on chlorophyll content of leaf chili followed Mack Kinner methode by doing seed treatment aplication. Colonization and chlorophyl content of chili leaf was done on 7 MPI. The research design used Random Block Design non factorial, data was analysis by 8 STAT. The result showed all of Beauveria bassiana isolates were able to colonize and established as endophytic in chili plant.Beauveria bassiana of wheat isolate was the best isolate giving spurring germination and seedling plant growth and not significant with B.bassiana isolate from Leptocorisa acuta insect. Aplication of B.bassiana isolates was able to increase the chlorophyll contentof chilileaf compared control. All of the tested B.bassiana fungus could increased chlorophyl-b content and chlorophyl totally of chili leaf, whereas chlorophyl-a content all of tested isolates was not significant. From its research showed there were corelation between colonization and leaf chlorophyll content, the higher percentage of endophytic fungus on leaf chili, it made higher the chlorophyl-b content and chlorophyl totally content of leaf chili.

Virulence of the Entomopathogenic Fungi Metarhizium spp. From Various Rhizosphere Against Pest Walang Sangit (Leptocorisa acuta thunb.)

Virulence of the Entomopathogenic Fungi Metarhizium spp. from Various Rhizospheres Against the Pest Walang Sangit (Leptocorisa acuta Thunb.). Metarhizium spp. is a type of entomopathogenic fungus that can be used to control Leptocorisa acuta. The purpose of this study was to obtain isolates of the fungus Metahrizium spp. which is virulent from various rhizospheres against L. acuta. The results of this study are expected to produce bioinsecticides with active ingredients from the entomopathogenic fungus Metahrizium spp. which are effective for controlling L. acuta pests in rice plants. Entomopathogenic fungal isolates Metarhizium spp. The samples used came from various plant rhizospheres in different regions, namely Met1a (Metarhizium spp. from the leek rhizosphere, Tanah Datar area), Met3b (Metarhizium spp. from the leek rhizosphere, Pua Agam River area), MetcTd (Metarhizium spp. from red chili rhizosphere, Tanah Datar area), Met2d (Metarhizium spp. from leek rhizosphere, Padang Lua Agam area), and MetKtBs (Metarhizium spp. from peanut rhizosphere, Batusangkar area). The results showed that some isolates of the entomopathogenic fungus Metarhizium spp. had a very significant effect on the mortality of L. acuta nymphs, L. acuta imago formed and duration of death of L. acuta. Treatment C (Met3b: Metarhizium spp. from leek rhizosphere, Pua Agam River area) was the best treatment among other treatments, with the mortality of 3 instar L. acuta nymphs of 100%, the number of imago formed 0% and the duration of death of 3 instar L. acuta nymphs with an average time of 4.50 days.

The presence of refugia and population of insect pest in rice field

Refugia is a type of plant playing the role as a food source and shelter for natural enemies in extreme environmental conditions. Legumes, food plants and flowering plants are used as refugia. The purpose of the research is to study the dominant pest population in the embankment of rice fields planted with refugia. The research was conducted in Tanasitolo village, South Sulawesi from June to November 2017. The study used a Randomized Block Design of five treatments and repeated it four times. The research was started by planting several different plants as refugia in the embankment of rice fields, namely: P0 = embankment without plant (control); P1 = maize and soybean in embankment; P2 = flowering plants in embankment; P3 = taro and banana in embankment; and P4 = long beans in embankment. The results showed that rice fields used various plants as refugia, the insect population was in the lowest number. The results showed that Valanga sp. were not found in P1 when the rice was 56 and 63 days after planting. The number of Nephotettix virescens (0.5 individuals) when the rice was 42 days after planting. Leptocorisa acuta has the lowest population at P1 and P3 in the age 84 days after planting (10.5 individuals). The conclusion of the experiment is the lowest population of grasshopper L. migratoria in rice age 56 and 63 days after planting was showed P1 (maize and soybean). The lowest population of green leafhopper N. virescens in the rice age 42 days after planting showed in the treatment P1 (maize and soybean). In the rice age in the 84 days after planting with treatment P1 (maize and soybean) and P3 (taro and bananas) showed a very low population.

Application of the combination of Calontropis gigantea L. and Crescentia cujete L. against Schirpophaga innotata and Leptocorisa acuta Thunb. and predator in paddy plants

C. gigantea L. and C. cujete L. are plants that contain secondary metabolites that can act as insecticides. This study aimed to evaluate the implications of C. gigantea and C. cujete to reduce the population and intensity of attack by stem borer (S. innotata) and stink bug (L. acuta) which are the main pests of paddy plants. This study consisted of 4 treatments consisting of a mixture of C. gigantea and C. cujete extracts, C. gigantea extracts, C. cujete extracts, and control with 5 replications. The extract made by fermentation ant the extract was applied at the age of 1 month after planting with a concentration of 5% for 8 times with a frequency of 1 time a week. Observation parameters were population and attack intensity of S. innotata and L. acuta as well as natural enemy population. The results obtained were that the treatment of all extracts could reduce the population and intensity of attacks compared to the control. Treatment of the mixture of C. gigantea and C. cujete extracts can reduce the population and the intensity of attacks is higher than without the mixture. Predator is not affected by extract applications.

Diversity Of Insect Pests In Rice Plant (Oryza Sativa L) in The Rice Fields Of South Kualuh District, North Labuhanbatu

Eradicating rice pests in South Kualuh is difficult to do optimally, because most farmers do not understand the types of pests that attack their rice plants. The objective of this study was to obtain information about the type of pest insects in rice plants and to find out the diversity index of insect pests in rice plants. This research was conducted using trap method and collection of insects was done using a insect net. Observation data was analised using Shanon Wiener (H) diversity / diversity index. The result showed 13 types of pest insects which belongs to 10 families. That is Tettigonia sp.(Linnaeus, 1758), Sogatella furcifera (Horváth, 1899), Nephotettix virescens (Distant, 1908), Cofana spectra (Distant, 1908), Atractomorpha crenulata (Fabricius, 1793), Erotides sp.(Laporte, 1836), Leptocorisa acuta (Thunberg, 1783), Aulacophora indica (Gmelin, 1790), Chrysochus cobaltinus (LeConte, 1857), Silba capsicarum (McAlpine, 1956), Hercostomus germanus (Wiedemann, 1817), Cnaphalocrosis medinalis (Guenée, 1854), Scirpophaga incertulas (Walker, 1863). The diversity index of rice pest insects was categorized as moderate with a value of 2,35 and a dominance index of 0,108. This value indicates that the distribution of species is evenly distributed so that no insect species dominates in the area.