Population Dynamics Of Insect Pests Research Articles

Low concentrations of cyantraniliprole negatively affects the development of Spodoptera frugiperda by disruption of ecdysteroid biosynthesis and carbohydrate and lipid metabolism

In addition to the acute lethal toxicity, insecticides might affect population dynamics of insect pests by inducing life history trait changes under low concentrations, however, the underlying mechanisms remain not well understood. Here we examined systemic impacts on development and reproduction caused by low concentration exposures to cyantraniliprole in the fall armyworm (FAW), Spodoptera frugiperda, and the putative underlying mechanisms were investigated. The results showed that exposure of third-instar larvae to LC10 and LC30 of cyantraniliprole significantly extended larvae duration by 1.46 and 5.41 days, respectively. Treatment with LC30 of cyantraniliprole significantly decreased the pupae weight and pupation rate as well as the longevity, fecundity and egg hatchability of female adults. Consistently, we found that exposure of FAW to LC30 cyantraniliprole downregulated the mRNA expression of four ecdysteroid biosynthesis genes including SfNobo, SfShd, SfSpo and SfDib and one ecdysone response gene SfE75 in the larvae as well as the gene encoding vitellogenin (SfVg) in the female adults. We also found that treatment with LC30 of cyantraniliprole significantly decreased the whole body levels of glucose, trehalose, glycogen and triglyceride in the larvae. Our results indicate that low concentration of cyantraniliprole inhibited FAW development by disruption of ecdysteroid biosynthesis as well as carbohydrate and lipid metabolism, which have applied implications for the control of FAW.

INSECT BIODIVERSITY AND ASSESSMENT OF POST-HARVEST GRAIN LOSSES IN STORED COWPEA (Vigna aunguiculata L.)

Insect pests cause huge economic losses to stored grain cereals and pulses in tropical and subtropical areas around the globe. The level of damage and losses caused by different insect pests varies depending upon the infesting species, type of food materials, duration of storage and structures. The information about the diversity of infesting species, their dispersal and abundance are key for devising effective pest management techniques against storage insect pests. The present study aimed to collect information on the distribution, relative abundance and biodiversity of major insect pests of stored cowpeas in Dera Ismail Khan (Khyber Pakhtunkhwa) and its adjoining Punjab province areas of Pakistan. The areas selected for biodiversity studies were Paniala, Mankera, Bhakkar, Paharpur, Kulachi, Ramak, Dera Ismail Khan, Darya Khan, Notak and Behal. A vast survey of godowns was conducted to find out the population dynamics of insect pests of stored cowpeas and to explore the % grains damage and weight losses in the mentioned areas. For the collection of samples, a spear sampler was used to collect 500-gram samples from the top, middle and bottom portions of the bags. Samples were preserved in plastic containers and after 30 days, were sieved out with the help of a 2mm mesh sieve to remove different types of dead and alive insects. A total of five species representing two distinct orders i.e., Coleoptera and Lepidoptera. Coleopterans are Callosobruchus maculatus, Tribolium castaneum, Oryzaephilus surinamensis, Trogoderma granarium belonged to four families including Chrysomelidae, Tenebrionidae, Silvanidae, Dermestidae and Lepidopteron are Sitotroga cerealella belonging to family Gelechidae. The most abundant species among all the recorded insect pests of cowpea was C. maculatus (53.60%) followed by T. castaneum (18.60%), S. cerealella (16.97%), O. surinamensis (6.49%) and T. granarium (04.34%). The maximum infestation (26.98%) and weight loss (28.91%) of cowpea was recorded in Darya Khan followed by Dera Ismail Khan (22.70% and 26.33%), whereas; minimum % infestation and weight losses were recorded in Bhakkar (16.91% and 17.14%) area showing significant differences between the surveyed areas. The C. maculatus is the most abundant specie of the stored cowpea grains in the surveyed areas and needs management tactics to minimize the post-harvest grains losses. The population of C. maculatus starts to build up during the month of March (23.30⁰C and 56.25% RH) and reaches at peak in May (35.32⁰C and 68.88% RH). Special measures should be taken during these months to minimize the infestation and losses caused by C. maculatus.

Population Dynamics of Insect Pests of Pea

The seasonal incidence of major insect pests on pea Pisum sativum at different growth stages has been assessed in this study. Major pests observed include gram pod borer Helicoverpa armigera (Hubner), blue butterfly Lampedes boeticus (L.), pea leaf miner Chromatomyia horticola Goureau and pea aphid Acyrthosiphon pisum (Harris). These results revealed that peak incidence of H. armigera (7.80 larvae/ plant) and L. boeticus (8.60 larvae/ plant) was during the 8th and 9th SMW, respectively; while for C. horticola (5.50 larvae/ leaf) and A. pisum (94.1 aphids/ plant) it was 5th SMW. Helicoverpa armigera incidence revealed a significant negative correlation with minimum temperature (r= -0.628) while for L. boeticus it was positive one with maximum temperature (r= 0.604). The incidence of C. horticola was observed to be significantly negatively correlated with minimum temperature and rainfall (r= -0.826 and r= -0.584, respectively); while A. pisum revealed a significant negative correlation with minimum temperature (r= -0.806).

Study of Population Dynamics of Insect-pests in Different Growing Environments and their Relationship with Microclimate of Pigeonpea Cultivars

Background: Pigeonpea is a low input, rainfed crop that provides economic returns every part of the plant. Insect-pests are the major biotic constraints limiting the productivity of this crop. Keeping all these factors in mind, the present experiment was conducted to study the population dynamics of insect-pests in different growing environments and their relationship with microclimate of pigeonpea cultivars. Methods: A field experiment was conducted at research farm of Department of Agricultural Meteorology, Chaudhary Charan Singh Haryana Agricultural University, Hisar, during Kharif season 2017. Insect-pests population was recorded from the five tagged plants at weekly interval starting from 38th standard meteorological week (SMW) till harvesting of the crop. Ground sheet method was used to record the population of larvae of M. vitrata and H. armigera. Larvae of M. vitrata and H. armigera falling on cloth sheet of size 60 cm × 60 cm laid near plant stem were counted. Web formed by M. vitrata larvae were visually counted and then removed to count larvae feeding inside the webs. Result: In our experiment, it was found that H. armigera infestation started from 38th SMW in all the varieties and D1 and D2 sown crop while in D3 sown crop it started in 40th SMW. On the other hand the larval population of M. vitrata started from 38th SMW, 39th SMW and 40th SMW in all varieties and D1, D2 and D3 sown crops, respectively where as the formation of webs in all the varieties and D1 sown crop started from 38th SMW while in D2 and D3 sown crops started from 39th SMW and continued till 45th SMW. Mean larval population of H. armigera, M. vitrata and number of webs per plant was found highest in D1 sown crop on variety Manak.

Diversity and Population Dynamics of Insect Pests of Mustard Crop in Hot Arid Region of Rajasthan

Diversity and Population Dynamics of Insect Pests of Mustard Crop in Hot Arid Region of Rajasthan

Conservation agriculture based crop management practices impact diversity and population dynamics of the insect-pests and their natural enemies in agroecosystems

Human efforts to grow abundant food through the persistent use of resource-intensive farming practices have resulted in declining soil health, and deterioration of ecosystem functions and services. Conservation agriculture (CA) has emerged as a practice to minimize the impacts of conventional resource-exhaustive and energy-intensive agriculture. Minimum soil disturbance, permanent soil cover, and diversification are the key components of CA. Tillage through conventional practices on the other hand has detrimental effects on the soil and environment as it requires deep inversion of soil with instruments such as mouldboard plow, disc plow etc. leaving very less organic matter in soil after establishment of crop. Even though, CA advocates many benefits over conventional agriculture in terms of soil and water conservation, the consequent changes in moisture and temperature regimes due to reduced tillage and surface cover would likely going to influence the biological activity, including insect pests and their natural enemies which dwell within these agroecosystems. The changed crop conditions under CA may favor particular insect communities and their ecological niches. The adoption of such practices may lead to decrease in insect pests with major activity on the crop canopy. However, the activity of the insect pests that spend their maximum life span at the soil surface or beneath the soil surface may increase. Recent insect-pest outbreaks in North-Western India and imbalances reported in Indo-Gangetic Plains point to the need for a better understanding of the inter-relationships between tillage intensity, residue retention, and insect pest population dynamics. The current review analyzes the existing state of knowledge of these dynamics and presents the scenarios that may emerge as CA get more acceptance. This review will help to develop countermeasures to improve performance and ecosystem services of Conservation agriculture (CA) based cropping systems.

Seasonal forecasting of pest population dynamics based on downscaled SEAS5 forecasts

Among the varied environmental factors that influence insect life-history, temperature has a relatively profound effect that can be mathematically estimated with non-linear equations. Thus, many models that aim to predict insect-pest population dynamics use meteorological data as input to descriptive functions that predict the development rate, survival and reproduction of pest populations. In a previous study, we developed a temperature-dependent population dynamics model for the global insect-pest Bemisia tabaci, and verified its accuracy under field conditions. In the current work, which focused on Northern Israel, seasonal meteorological forecasts from the ECMWF SEAS5 coupled model were spatially and temporally stochastically downscaled by a weather generator tool using records from ERA5-Land reanalysis and meteorological stations. The local, hourly temperature time series served as input data to a population dynamics model, creating an ensemble of seasonal population forecasts from which probabilistic predictions could be made already at the beginning of the season (which lasts from March to November). Post-hoc evaluation of the seasonal forecast was done using the observed station temperatures as model input. Comparisons to predictions made using climatologic temperatures found the weather generator-based ones much more accurate in predicting the timing of each insect generation, although there was no difference between the two approaches in predicting the population size. Moreover, the weather generator-based predictions highly matched field observations made by pest inspectors during the growing season of 2021. Taken together, our findings indicate that the developed forecasting tool is capable of providing decision makers with the supporting data required for smart seasonal planning and economical- and environmental-driven optimal management of agricultural systems.

Population Dynamics of Insect Pests and Beneficials on Different Snap Bean Cultivars

Snap bean is an important crop in the United States. Insecticides are commonly used against pests on snap bean, but many pests have developed resistance to the insecticides and beneficials are threatened by the insecticides. Therefore, host plant resistance is a sustainable alternative. Population dynamics of insect pests and beneficials were assessed on 24 snap bean cultivars every week for six weeks. The lowest number of sweetpotato whitefly (Bemisia tabaci) eggs was observed on cultivar 'Jade', and the fewest nymphs were found on cultivars 'Gold Mine', 'Golden Rod', 'Long Tendergreen', and 'Royal Burgundy'. The numbers of potato leafhopper (Empoasca fabae) and tarnished plant bug (Lygus lineolaris) adults were the lowest on cultivars 'Greencrop' and 'PV-857'. The highest numbers of adults were found in Week 1 (25 days following plant emergence) for B. tabaci and Mexican bean beetle (Epilachna varivestis); Week 3 for cucumber beetle, kudzu bug (Megacopta cribraria), and E. fabae; Weeks 3 and 4 for thrips; Week 4 for L. lineolaris; and Weeks 5 and 6 for bees. Temperature and relative humidity correlated with B. tabaci, E. varivestis, bee, and predator ladybird beetle populations. These results provide valuable information on the integrated pest management of snap beans.

Heat shock protein 70 and Cathepsin B genes are involved in the thermal tolerance of Aphis gossypii.

Elevated temperature can directly affect the insect pest population dynamics. Many experimental studies have indicated that high temperatures affect the biological and ecological characteristics of the widely distributed crop pest Aphis gossypii, but the molecular mechanisms underlying its response to heat stress remain unstudied. Here, we used transcriptomic analysis to explore the key genes and metabolic pathways involved in the regulation of thermotolerance in A. gossypii at 29 °C, 32 °C, and 35 °C. The results of bioinformatics analysis show that few genes were consistently differentially expressed among the higher temperature treatments compared to 29 °C, and a moderate temperature increase of 3°C can elicit gene expression changes that help A. gossypii adapt to warmer temperatures. Based on KEGG pathway enrichment analysis, we found that genes encoding four heat shock protein 70 s (Hsp70s) and nine cathepsin B (CathB) proteins were significantly upregulated at 35 °C compared with 32 °C. Genes related to glutathione production were also highly enriched between 32 °C and 29 °C. Silencing of two Hsp70s (ApHsp70A1-1 and ApHsp68) and two CathBs (ApCathB01 and ApCathB02) with RNA interference using a nanocarrier-based transdermal dsRNA delivery system significantly increased sensitivity of A. gossypii to high temperatures. A. gossypii is able to fine-tune its response across a range of temperatures, and Hsp70 and CathB genes are essential for adaption of A. gossypii to warmer temperatures. © 2023 Society of Chemical Industry.

Population dynamics of insect pests of sunflower (Helianthus annus L.)

Population dynamics of insect pests of sunflower (Helianthus annus L.)

Population Dynamics of Insect Pests Associated with Cabbage and Cauliflower and Farmers’ Friendly IPM

A field survey in the farmers’ fields at Gurugram in Haryana, in few blocks focused on the incidence of pests of cabbage and cauliflower during rabi, 2017-18 and 2018-19. These revealed the occurrence of Plutella xylostella and Spodoptera litura. Maximum number of larvae of P. xylostella and S. litura was recorded in Pataudi block as compared to those of Farukhnagar, Sohana and Gurugram. Seven neem-based biopesticides were evaluated along with check carbosulfan at hot spots. Data revealed that NSKE 5% was quite effective followed by Nimbicidin and Neemgold. The cost benefit ratio was maximum with NSKE (1:9.41, 1:9.53 for cabbage and cauliflower, respectively) followed by neem leaf extract (NLE) with (1:7.72 and 1:6.31). These results conclude that NSKE and NLE can be recommended against major pests of cabbage and cauliflower.

Effects of Climate Elements on Population Dynamics of Insect Pests of Cocoa- A Review

Effects of Climate Elements on Population Dynamics of Insect Pests of Cocoa- A Review

Incidence and population dynamics of insect pests infesting pomegranate orchards in Kullu district of Himachal Pradesh, India

ISHS V International Symposium on Pomegranate and Minor Mediterranean Fruits Incidence and population dynamics of insect pests infesting pomegranate orchards in Kullu district of Himachal Pradesh, India

Effect of Maize–Legume Intercropping on Maize Physio-Agronomic Parameters and Beneficial Insect Abundance

In developing countries, intercropping is commonly used to boost land productivity and agricultural benefits. However, in the Yucatan region of Mexico, maize (Zea mays L.) yields remain low, despite consistent fertilizer and pesticide inputs in traditional intercropping systems. Furthermore, little is known about the photosynthetic mechanisms that occur when maize plants interact with legumes, and there is a lack of understanding of how intercropping systems affect other organisms in the system, such as beneficial and insect pest population dynamics. A field experiment was carried out on the Yucatan Peninsula in 2021 to assess the impact of maize–legume intercropping systems on maize yield, physiological characteristics as evaluated by gas exchange measurements, and the abundance of beneficial insects in traditional and novel maize intercropping systems. The experiment was carried out with a randomized complete block design with three replicates. Treatments included maize intercropped with a novel legume, crotalaria (Crotalaria juncea L.), maize intercropped with a traditional legume, cowpea (Vigna unguiculata (L.) Walp.), and sole maize as a control. Significant differences in plant height were shown at growth stages V12 (45 days after sowing) and VT (60 days after sowing). No differences were observed in stem diameter, leaf area index, or chlorophyll content. The maize/cowpea intercrop increased the photosynthesis rate by 12.9% and 9.84% in the maize/crotalaria and sole maize, respectively (p < 0.001), and transpiration rate by 6.5% and 8.5% in the maize intercropped with crotalaria and sole maize treatments, respectively (p < 0.001), of maize plants. No significant effects on stomatal conductance or water use efficiency were observed, but the carbon intercellular rate was reduced by 9.74% and 9.15 when compared to the maize/crotalaria and the sole maize treatments, respectively. Overall, intercropping treatments attracted more beneficial insects than sole maize. For predators, the families that stood out were Coccinelidae, Formicidae, Araneidae, Thomisidae, Syrphidae, Chrysomelidae, Oxypidae, Vespidae, Reduviidae, Carabidae, Asilidae, Salthicidae, Dolichopodidae, while among parasitoids, the most frequent families were Eurytomydae, Braconidae, Tachinidae, Pteromalidae, Scelionidae, and Figitidae. In comparison to the maize/cowpea and maize/crotalaria treatments, the sole maize treatment resulted in a grain yield increase of 24.5% and 32%, respectively. However, sole maize was not statistically different to that of maize/cowpea intercropping. In conclusion, our findings suggest that maize/cowpea intercropping could be a viable alternative to sole maize cropping systems for enhancing maize yield and the abundance of beneficial insects, without increasing interspecific competition with the maize crop. Therefore, the maize/cowpea intercropping system represents a sustainable planting alternative for promoting maize grain yield and also promoting edible legume production within the system. Furthermore, the outcomes of this study can serve as a theoretical framework for increasing maize–legume intercropping profitability under growing conditions on the Yucatan Peninsula.

Population dynamics of insect pest and natural enemies of castor (Ricinus communis L.) under different intercrops

A field experiment was conducted at Tapioca and Castor Research Station, Tamil Nadu Agricultural University, Yethapur, Tamil Nadu during kharif 2015 and rabi 2016 to study the population dynamics ofinsect pests and natural enemies in different castor intercrops. The defoliators population was significantly lesser in castor + red gram+ pearl millet intercropped treatments than in the sole castor crop, which served as a control. The cumulative mean number of sucking pest population was found to be lesser in (castor + red gram), followed by castor + red gram + pearl millet intercrop system. Capsule borer percentage infestation is significantly lesser in castor + red gram + pearl millet intercropped treatments with increased percentage parasitization byMicropliti macullipennis and Apanteles angaleti.

An expert system for insect pest population dynamics prediction

Avocado (Persea americana) production is increasing in Kenya, with both small and largeholder farming for domestic and export markets. However, one of main challenges that limit production is infestation by insect pests, notably the oriential fruit fly Bactocera dorsalis and Ceratitis spp. fruit flies, which cause direct crop losses and are indirectly responsible for non-tariff trade barriers due to stringent export requirements. Data on weekly pest trap counts were collected between September 2017 and December 2020 within orchards in avocado plantations. Fuzzy neural network (FNN) were used to model the population dynamics of B. dorsalis and Ceratitis spp. Weekly pest counts, rainfall, average temperature, relative humidity and avocado plant physiological stages were used for predictive modeling in different orchards. The performance of the resulting models was evaluated using coefficient of determination (R2), mean absolute error (MAE), mean relative approximation error (MRAE) and root mean squared error (RMSE). FNN models achieved satisfactory results in predicting the dynamics of the pests in the orchards, with most of the models obtaining R2 > 0.85. We demonstrated how FNN models can be used as predictive tools for managing and controlling fruit fly pest populations in these plantations, and how they may be suitable to predict fruit fly or other pests in similar cropping systems. Once the input variables are known, they can be loaded into the FNN models to predict field pest populations, and based on threshold values, allow for implementation of timely and adequate control measures such as the use of biopesticides.

Population Dynamics of Rice Insect Pests through Light Trap Catches and Its Relation to Abiotic Factors in High Altitude Tribal Zone of Seethampeta in Andhra Pradesh, India

Studies were carried out at Agricultural Research Station, Seethampeta in Andhra Pradesh during the kharif season for three consecutive years starting from 2017 to 2019 on the population dynamics of insect pests occurring in paddy and also to assess the influence of weather parameters on insect pests. The insect pests observed in the light trap catches were, Yellow stem borer, Gall midge, Leaf folder, Green leafhopper, Plant hopper (BPH/WBPH) and Grasshoppers. The light trap catches of rice insect pests were recorded at weekly interval during 32nd Standard Meteorological Week (SMW) to 52nd Standard Meteorological Week (SMW) and the data were correlated with the weather parameters. The results revealed that more number of adults of Yellow stem borer were noticed during the year 2019 from 45th to 48th SMW and the correlation studies revealed that that maximum temperature, minimum and maximum relative humidities had significant positive influence and regression value of R2 (743, 638 and 726 during 2017, 2018 & 2019). The population of gall midge was negligible during the year 2017 and 2018. Whereas, in 2019 peak was notice during 38th SMW (15 No’s) maximum relative humidity has positive relation with increase in the gall midge population. Leaf folder adults were trapped more in the light traps during the year 2019 with peak catches of 11.00 No’s on 42nd SMW and were positively correlated with maximum temperature, minimum and maximum relative humidities. Similarly, leafhopper, brown leaf hopper, grass hoppers were positively correlated with the relative humidity.

Nutrition and weather effects on population dynamics of insect-pests in potato (Solanum tuberosum)

Insect population studies were conducted to estimate the relative population abundance of sucking insect-pests on potato (Solanum tuberosum L.) in relation to nutrition management and weather parameters at Punjab Agricultural University, Ludhiana, India during rabi 2014-15 and 2015-16. The lowest and the highest aphid, jassid and whitefly populations were recorded with recommended dose of manures and fertilizers (T1-RDMF), and the unfertilized control (T10), respectively during 46th to 51st Standard Meteorological Week (SMW). Seasonal fluctuation of insectpest- infestation revealed that the weather parameters influenced the insects population. The aphid population was the lowest (0.27/plant) during 46th SMW and it increased with advancement in the crop growth stage with its highest population (3.43/plant) during 52nd SMW. Contrary to the aphid population, the highest populations of jassid (2.89/ plant) and whitefly (2.23/plant), irrespective of the nutrition treatments, were recorded during 47th SMW, and decreased with advancement of the crop-growth stage with the lowest population (0.49 jassid and 0.55 whitefly/plant) being during 52nd SMW. A negative correlation was observed between the aphid population, and the maximum-(Tmax) and minimum-temperatures (Tmin) and sunshine hours (SH) but the positive correlation with relative humidity (RH). However, the trends for the jassid and whitefly populations were the opposite.

Studies on population dynamics of major pests of Ailanthus excelsa Roxb

Aim: To study the peak period of incidence of major pest of Ailanthus excelsa. Methodology: Seasonal abundance of major insect pests of A. excelsa viz., ailanthus defoliator and ailanthus webworm were studied in 5-year-old plantation at Forest College and Research Institute, Mettupalayam from April, 2018 to March, 2019. Weekly observations were made on the abundance of major insect and pest population which were correlated with weekly weather parameters. Results: Monitoring the population dynamics of insect pests revealed that the major key pests were ailanthus defoliator and webworm. The highest number of ailanthus defoliator (38.00 larvae per tree) and webworm (33.90 larvae per tree) were recorded during 44th standard week in 5-year-old plantation. Correlation analysis revealed that maximum temperature (Tmax) was negatively correlated with ailanthus defoliator with the r value of -0.299. Regarding webworm, wind velocity and evaporation rate were negatively correlated with the r value of -0.412 and -0.361 and was found to be statistically significant at 1% level. Interpretation: Seasonal abundance of this information helps us to take decision for the management of A. excelsa pests.

Population dynamics of major insect pests of soybean and their correlation with abiotic factors in Bundelkhand agroclimatic zone of M. P.

Population dynamics of insect-pests of soybean and there a correlation with abiotic factors were studied at JNKVV, College of Agriculture, Tikamgarh (M.P.).The observations on the incidence of various insect-pests were recorded from germination to harvesting of the crop at weekly intervals. The peak activity of semilooper (5 larvae/mrl) and tobacco caterpillar (1.33 larvae/mrl) were observed in 37th and 38th SMW respectively. Whereas the highest population of jassid (3.17 jassid/ 3 leaves /plant) was recorded during 36th SMW and there was two peaks in whitefly population first was 33rd SMW (9.17 per 3 leaves /plant) and second peak was 37th SMW (14.33 per 3 leaves/plant). However the maximum infestation due to stem fly was observed 18.45% tunnel of the stem in 35th SMW, while the maximum infestation of plant due to girdle beetle was observed 4.33 girdle plant /mrl during 39th SMW. Based on observations and correlation study of insect incidence with weather parameters, it was found that population of semilooper and tobacco caterpillar larva were significant and positive correlated with maximum temperature and evaporation (r = 0.31, 0.35, 0.55 and 0.61 respectively) and negatively correlated with evening humidity (r =.-0.18 and -0.43 respectively). Whereas the population of whitefly and jassid were significant positive correlated with maximum temperature and evaporation (r = 0.36, 0.24, 0.41 and 0.48 respectively) and negatively correlated with evening relative humidity. However stem fly population was significantly positive correlated with maximum temperature and evaporation (r =0.86 and 0.64 respectively) and negatively correlated with rainfall (r =-0.44). The girdle beetle population was also significantly positive correlated with maximum temperature and evaporation (r = 0.89 and 0.71 respectively) and negatively correlated with relative humidity and rainfall (r = -0.60, -0.89 and -0.44 respectively). From the study it may be concluded that there were two peaks in whitefly population (33rd & 37th SMW) and one peak of jassid, semiloope and tobacco caterpillar were recorded at 36th, 37th and 38th SMW respectively. However the maximum infestation of stem fly and girdle beetle were observed during 35th and 39th SMW respectively. It was also concluded that all the insects exhibited significant positive correlation with maximum temperature and evaporation while the stem fly and the girdle beetle showed significant negative correlation with minimum temperature, relative humidity and rainfall respectively.