Aphid Population Dynamics Research Articles

From a local descriptive to a generic predictive model of cereal aphid regulation by predators.

The temporal dynamics of insect populations in agroecosystems are influenced by numerous biotic and abiotic interactions, including trophic interactions in complex food webs. Predicting the regulation of herbivorous insect pests by arthropod predators and parasitoids would allow for rendering crop production less dependent on chemical pesticides. Curtsdotter etal. (2019) developed a food-web model simulating the influences of naturally occurring arthropod predators on aphid population dynamics in cereal crop fields. The use of an allometric hypothesis based on the relative body masses of the prey and various predator guilds reduced the number of estimated parameters to just five, albeit field-specific. Here, we extend this model and test its applicability and predictive capacity. We first parameterized the original model with a dataset with the dynamic arthropod community compositions in 54 fields in six regions in France. We then integrated three additional biological functions to the model: parasitism, aphid carrying capacity and suboptimal high temperatures that reduce aphid growth rates. We developed a multi-field calibration approach to estimate a single set of generic allometric parameters for a given group of fields, which would increase model generality needed for predictions. The original and revised models, when using field-specific parameterization, achieved quantitatively good fits to observed aphid population dynamics for 59% and 53% of the fields, respectively, with pseudo-R2 up to 0.99. But the multi-field calibration showed that increased model generality came at the cost of reduced model reliability (goodness-of-fit). Our study highlights the need to further improve our understanding of how body size and other traits affect trophic interactions in food webs. It also points up the need to acquire high-resolution data to use this type of modelling approach. We propose that a hypothesis-driven strategy of model improvement based on the integration of additional biological functions and additional functional traits beyond body size (e.g., predator space search or prey defences) into the food-web matrix can improve model reliability.

Efficacy of some botanical insecticides against <em>Aphis gossypii</em> Glover (Hemiptera: Aphididae) on chrysanthemum

An evaluation of various botanical insecticides to control Aphis gossypii and its impact on aphid population dynamics on chrysanthemum plants was investigated. In order to control A. gossypii on chrysanthemum, the effectiveness of several botanical insecticides extracted from Melia azedarach, Toona sinensis, and Chrysanthemum cinerariaefolium was investigated in the current study. The research was carried out in the experimental field of the Indonesian Ornamental Crops Research Institute under plastic house conditions. Five concentrations, i.e., 1.5, 2.0, 2.5, 3.0, and 3.5 g/L of three plant extracts, M. azedarach, T. sinensis, and C. cinerariaefolium, were sprayed on chrysanthemum cultivar White Fiji after 28 to 84 days after planting. A. gossypii had a dynamic population that changed according to the plant’s developmental stages. In vegetative growth, the alate adult and nymphal stages were dominant, and the population of nymphs increased along the plant ages. The insect colonized young leaf surfaces in the terminal apices. During the reproductive stages, the population of alate adults diminished, and the distribution of the insect extended to mature, old leaves, flower buds, and bloomed flowers. The application of several botanical insecticides revealed various responses of aphid populations. Among the tested insecticides, C. cinerariaefolium extract at 3.0 and 3.5 g/L demonstrated the highest average percentage efficacy (76 and 72%) and was the most consistent in suppressing the population. The results of this study indicate the potential efficacy of botanical insecticides against A. gossypii suggesting a different approach to efficient and environment-friendly chrysanthemum pest management.

Incidence, transmission, host range and population dynamics of aphids transmitting bean common mosaic virus of cowpea

Cowpea [Vigna unguiculata (Linn.) Wilczek] is an important pulse crop which belongs to family Fabaceae. Bean Common Mosaic is a major viral disease in cowpea resulting in significant yield losses to a tune of 70 per cent. The results showed that disease was widespread in all the surveyed areas, with the highest average per cent disease incidence being observed in Bagalkote (29.82%) followed by Vijayapur (27.41%), Dharwad (25.47%) and Belagavi district (18.89%). The disease incidence varied from 3.25 per cent to 69.56 per cent among the villages and from 12.94 per cent to 44.80 per cent among the taluks. The host range and transmission studies revealed that BCMV infecting cowpea is readily transmissible by sap, aphids and through seeds. The mechanical transmission was 71.43 per cent, aphid transmission was found to an extent of 54.42 per cent and the seed transmission of BCMV infecting cowpea was 64.00 per cent. The population of aphid (Aphis craccivora) was maximum during the 38th and 39th Standard Meteorological Weeks (SMWs) with the mean value of 92.70 and 81.20, respectively. The aphid population varied at different crop stages. Aphid population build up showed a strong significant negative correlation with rainfall. There was a significant negative correlation with minimum temperature and morning RH.

Population Dynamics of Aphid Pests of Wheat and Their Natural Enemies

Four aphid species (Schizaphis graminum, Sitobion avenae, Rhopalosiphum padi and Diuraphis noxia) were observed when the population dynamics of aphids in four wheat varieties were analysed. Maximum population abundance (104± 1.79 aphids/ plant) was observed during middle of March. Rhopalosiphum padi and D. noxia were predominant throughout (52.86.1± 0.21 and 56.10± 0.24 aphids/ plant, respectively). The variety ANAJ-2017 showed the least incidence (26.28± 0.27 aphids/ plant) being more resistant. Aphid parasitism was also more in ANAJ-2017 with the parasites Aphidius ervi (15.35± 0.13) and Praon volucre (12.45± 0.12). Abundance of predators (ladybird beetle, green lace wing, syrphid fly and spiders) was observed with the highly infested varieties UJALA-2016 and FSD-2008. With incidence of aphids, temperature showed positive correlation while relative humidity (RH) and rainfall did not show any significant effect. The yield varied significantly among the tested varieties and it was found positively correlated with aphid incidence with ANAJ-2017 exhibiting the maximum 1000 grain weight (55 g).

SURVEILLANCE AND EVALUATION OF CLIMATIC FACTORS ON VARIETAL SCREENING AGAINST APHID POPULATION IN WHEAT

Aphids, as notorious pests in wheat cultivation, pose a significant threat to crop yield and quality. The dynamics of aphid populations in wheat fields are intricately linked to various climatic factors, making it crucial to understand and manipulate these interactions for effective pest management. This research presents a comprehensive study that combines surveillance and varietal screening to assess the impact of climatic variables on aphid populations in wheat crops. The study was conducted over growing seasons 2022-23, involving the systematic collection of data from wheat fields exposed to varying climatic conditions. These data were then analyzed to investigate the relationship between climatic factors, such as temperature, humidity, and rainfall, and aphid infestations. Additionally, varietal screening was performed to identify wheat cultivars with varying levels of resistance or susceptibility to aphids. The interactions between specific wheat varieties and aphid populations under different climatic conditions were evaluated. This information provides valuable insights into selecting appropriate wheat cultivars that can mitigate aphid-related losses. The survey findings indicate that the aphid population on various wheat varieties exhibited a range of infestation levels. Specifically, aphid populations were observed to vary between 8.7 and 10.7 aphids per tiller on Faisalabad-08, 7.2 and 11.3 aphids per tiller on Ujala-16, 7.9 and 12.2 aphids per tiller on Anaj-17, 7.7 and 9.2 aphids per tiller on Akbar-19, 7.3 and 11.4 aphids per tiller on Dilkash-21, 7.9 and 11.5 aphids per tiller on Subhani-21, and 8.8 and 10.6 aphids per tiller on MH-21, respectively. The findings of this study reveal the complex interplay between climatic factors and aphid population dynamics in wheat fields. Aphid population was maximum (1382.39/trap/week), when maximum and minimum temperature was 28.02 ℃ and 14.0 ℃, respectively with relative humidity 80.83% and 49.62% at 8am and 5pm, respectively. However, for varietal screening of 14 wheat varieties and advance lines, the lowest aphid population was recorded on wheat varieties/lines viz., Arooj-22(4.311), HYT-74(4.378), Dilkash-21(4.433), V-19308(4.778) and HYT-76 (4.789), and these were statistically at par with each other. While maximum aphid population was observed on V-19532 (12.711) followed by V-19317(11.433), V-19559 (10.711), V-19317 (11.433), V-19347 (10.244), Akbar-19 (7.656), and Subhani-21 (6.044). Overall, this manuscript contributes to the body of knowledge on integrated pest management strategies in wheat farming, emphasizing the importance of both surveillance and varietal screening in mitigating aphid-related threats in the face of changing climate patterns.

Indirect and direct interactions between grain aphid and parasitoid in the presence of symbiont Regiella insecticola

BackgroundAphids often harbor bacterial symbionts that confer resistance to biotic and abiotic stress. Previous studies have primarily examined the direct effects of symbiont infection on parasitoid success but less on aphid population dynamics under indirect parasitic situations, for example when exposed to parasitoid wasp odor. Deciphering this type of indirect effect is essential for understanding dynamics of insect ecosystems and communities and to improve IPM success.MethodsWe generated Sitobion avenae aphid clonal lines that are genetically identical but differ in Regiella insecticola infection. Then, the indirect odor effect of female parasitoid wasp Aphidius gifuensis (Ashmaed), one of its major natural enemies in the fields, was examined on the aphid lines fitness using different parasitoid densities. With these lines we also tested the direct effect of symbiont presence on aphid resistance against different parasitoid densities.ResultsOur study found fitness costs for the aphid line hosting Regiella, mainly via an increase in the development time and a reduction in population increase rate. Some of these fitness traits were influenced by the indirect exposure to parasitoid wasp odor with a density effect. Presence of the symbiont also reduced A. gifuensis parasitic success, increased the wasp development time and decreased its emergence weight with low effect of the parasitoid density used for parasitism.ConclusionsThese results showed that aphid population dynamic was mainly affected by the symbiont presence, but not by parasitoid odor. Symbiont presence also protected aphid from parasitism and affected parasitoid offspring weight and hence their future individual fertility and fitness.

PRUNUL TRANSGENIC HONEYSWEET ARE EFECT NEUTRAL ASUPRA DIVERSITĂȚII ȘI DINAMICII POPULAȚIILOR DE AFIDE ÎN CONDIȚII DE CLIMAT TEMPERAT- CONTINENTAL

‘HoneySweet’ is a genetically engineered plum resistant to Plum pox virus. Potential risks such as its impact on the diversity and dynamics of indigenous aphid populations was assessed. The study compared winged population of aphids visiting transgenic and conventional plums under continental temperate climatic conditions of Romania. The experimental analysis was conducted during three years (2016-2018) within an experimental plot containing transgenic (‘HoneySweet’) and conventional (‘Reine Claude d’Althan’ and ‘Stanley’) plums. This study revealed a similarity of both flight curves and the number and species of aphids landing on the two types of plum. Overall results showed no statistically differences between aphid species visiting the three cultivars, respectively the two types of plum. Consequently, our results support the hypothesis of the neutral effect of the transgenic plum on indigenous populations of aphids.

Population Dynamics of Mustard Aphid, Lipaphis erysimi (Kaltenbach) on Cauliflower in Relation to Biotic and Abiotic Factors

The field experiment was conducted at Horticulture Farm, S.K.N. College of Agriculture, Jobner during Rabi 2021/22 to know the population dynamics of mustard aphid, Lipaphis erysimi (Kaltenbach). The incidence of aphid started in the first week of December and second week of December remained active throughout the crop season during both years. The population of aphid gradually increased and reached to its peak in the second week of February and first week of February in Rabi, 2021/22, respectively. The correlation studies indicated that the aphid population had non-significant correlation with temperature, relative humidity and sunshine hours in both the years. Both the predators, ladybird beetle and syrphid fly had significant positive relationship with aphid population during both the years.

Population Dynamics of the Coriander Aphids in Hyper Arid Region of Rajasthan and their Correlation with Biotic and Abiotic Factors

Population dynamics of coriander aphid and their correlation with biotic and abiotic factors were studied at instructional farm of the department of Entomology, College of Agriculture, SKRAU Bikaner during Rabi, 2020-21 and 2021-22. The incidence of coriander aphid, H. coriandri (Das) commenced in the fourth week of January (4th SMW) and remained active throughout the crop season i.e. upto third week of March during both the years (2020-21 and 2021-22). The population of H. coriandri increased gradually and attained its peak in last week of February/first week of March (9th SMW) during both the years. After peak aphid population started declining and reached to low levels in the 11th SMW near maturity of the crop during both the years. Simultaneously the occurrence of predator, Coccinella septempunctata coincided with the population of aphids during both the years. Maximum and minimum temperatures had positive correlation with aphid population during both the years i.e. 2020-21, 2021-22. Morning and evening relative humidity showed negative correlation with aphid population. whereas, population of C. septempunctata was significant positively correlated with aphid population during both years.

Effect of Sowing on Population Dynamics of Aphid <i>Myzus persicae</i> (Sulzer) on Cumin

A field experiment was conducted to study the population dynamics of aphid, Myzus persicae (Sulz.) and to see the effect of sowing dates. Cumin variety Gujarat Cumin 4 (GC-4) was grown during rabi 2020-21. The incidence and population fluctuation was dependent on the weather parameters. The incidence initiated in third week of December (51st Standard Meteorological Week-SMW). Initially, incidence was low (6.00 aphids/three umbels) but it gradually increased and reached the peak in last week of January i.e. 5th SMW (115.03 aphids/three umbels). The early sown crop (26th October) had the minimum infestation (68.00 aphid/3 umbels) of aphids and highest seed yield (4.90 q/ ha) was obtained as compared to the late sowing crop on 7th December (106.50 aphids/ umbels) with minimum seed yield (3.10 q/ ha).

Population dynamics of aphid and their natural enemies in mustard based on meteorological parameters using principal component analysis

An experiment was conducted at the research farm of the Rajasthan Agricultural Research Institute, Durgapura, Jaipur, during Rabi, 2020–21 and 2021–22, to study the impact of meteorological parameters on the populations of the aphid, Lipaphis erysimi (Kalt) it’s associated natural enemies coccinellids, Coccinella septempunctata and syrphid flies, Xanthogramma scutellariae. The correlation coefficients with the pooled data, showed a substantial negative correlation of aphid population with temperature (r = -0.466 and -0.582*) as well as with average relative humidity (r =0.489*). C. septempunctata and X. scutellariae had positive significant correlations with L. erysimi (r = 0.965* and 0.988* respectively). The most significant variables for aphid populations, according to PC1 and PC2 (initial components of principal component analysis), are biotic factors and weather parameters.

The contribution of aphids (Aphidoidea) to atmospheric concentrations of Alternaria and Cladosporium spores

Honeydew extracted by aphids serves as nutrient for the development of sooty moulds. Hypothetically, population dynamics of aphids should therefore have an effect on the airborne levels of the spores of fungi colonizing honeydew. In this study, the effects of seven aphid taxa on Alternaria and Cladosporium spore seasons (both pathogenic and allergenic fungi) were analysed on a total of 20-year-long dataset in Kecskemét (Hungary), Leicester (UK) and Poznań (Poland). Meteorological factors strongly effected both aphid and fungal populations. In most cases, a direct effect of weather on fungal levels were found. Direct effect of two aphid species, Acyrthosiphon pisum and Euceraphis punctipennis, on the atmospheric concentration of Alternaria spores was identified in Leicester and Poznań in June and July respectively. Other aphid species had secondary, but significant effects during other time periods. This suggests aphid population data can be informative in predicting airborne concentrations of Alternaria and Cladosporium spores.Graphical abstract

Role of parasitoids and landscape structure in aphid population dynamics in winter canola

Three aphid species infest winter canola, Brassica napus L. fields in central Oklahoma and are serious pests: the cabbage aphid, Brevicoryne brassicae L., green peach aphid, Myzus persicae (Sulzer), and turnip aphid, Lipaphis pseudobrassicae (Davis). Mortality caused by parasitoids may be an important component of biological control of aphids in Oklahoma canola fields. Therefore, it is important to determine the effect of parasitoids on aphids in canola and the factors that affect it. We undertook a study during three consecutive growing seasons to: 1) estimate aphid suppression by parasitoids in each of 23 canola fields using cages that excluded natural enemies and cages that permitted access by parasitoids; and 2) evaluate how aphid parasitism in canola is related to the composition and configuration of the landscape surrounding each canola field. Parasitism was estimated using turnip aphid infested sentinel canola plants stationed in each field in autumn and in spring of each growing season. Two parasitoids with broad host ranges, Diaeretiella rapae (M’Intosh) and Aphelinus nigritus (Howard), parasitized turnip aphids in canola. There were fewer aphids and more parasitoids in cages that permitted access to parasitoids than in cages that excluded natural enemies. Partial redundancy analysis demonstrated that parasitism rate by D. rapae was positively related to landcover of wetlands and negatively related to contagion of patches. Parasitism by A. nigritus was positively but weakly associated with landcover of summer crops, but not with any other measured landscape variable. Wetlands in central Oklahoma agricultural landscapes apparently are habitat for aphid parasitoids from which they disperse to canola fields and parasitize aphids. Partial redundancy analysis showed that relative aphid density in fields was negatively related to parasitism by D. rapae. Results indicate that parasitoids suppress aphid infestations in canola fields and demonstrate potential for habitat management to improve biological control of aphids in canola.

Modeling the effects of plant resistance, herbivore virulence, and parasitism, on the population dynamics of aphids and parasitoids in wheat and soybean in different climates

Invasions by insects that become pests are an increasing problem for agriculture. Introductions of parasitoids from the regions of pest origin and breeding plants resistant to invasive pests can reduce the abundances and impacts of pests, while providing safe, sustainable alternatives to insecticides. However, impacts of parasitoids and plant resistance are likely to interact, and the abiotic environment, and in particular, climate change is likely to affect these interactions. Here I report results from simulations with mathematical models of population dynamics of aphids and parasitoids on resistant versus susceptible plants, parameterized with published results, designed to test the following hypotheses: (1) parasitoids can reduce abundances and frequencies of virulent aphids able to overcome plant resistance, (2) temperature regime affects the impacts of parasitoids on virulent aphids, and (3) the outcomes of these interactions vary with crop. Two systems were modeled: the soybean aphid, Aphis glycines, on soybean, and the Russian wheat aphid, Diuraphis noxia, on wheat. The parasitoids in the models are in the genus Aphelinus, species of which have a long association with biological control of invasive pests. In the simulations with these models, parasitoids reduced the abundances, and on wheat, the percent of virulent aphids. The impacts of parasitoids on virulent aphids were greater in southern locations than in northern locations, and the impacts on virulent aphids were greater on wheat than on soybean. Indeed, parasitoids actually increased the frequencies of virulent aphids on soybean when only susceptible plants were present, while reducing the abundance of all aphids. If one accepts that comparisons of population dynamics in southern versus northern locations indicate the likely affects of climate change in the northern locations, these results suggest that climate change would lead to decreased abundance and frequency of virulent aphids in northern locations.

Habitat Modification Alters Food Web Interactions with Focus on Biological Control of Aphids in Apple Orchards

To date, direct interactions between pests and natural enemies are often considered in biocontrol programs. Recently there has been an increase of evidence for the importance of third-party mediated indirect interactions in determining the population dynamics of insects. Predicting the strength of such interactions remains a central challenge in biocontrol assessments. Here, two field experiments were performed in two years to investigate to which extent Dysaphis plantaginea Passerini, Aphis pomi De Geer, and Myzus cerasi Fabricius might indirectly interact through shared natural enemies and ants. We first studied the population dynamics of target insects in isolated orchards of apples and cherries. Secondly, we investigated how the spatial coexistence of aphid-infested cherries can indirectly affect the population dynamics of apple aphids via natural enemies and ants. In the first experiment, nine parasitoid species were recorded on apple and cherry aphids, among them were three species in common. Six predatory families were found on cherry and apple aphids, while only one ant species, Lasius niger L., was found associating with these aphids. In the second experiment, temporal variation in the natural enemy-mediated apparent competition between M. cerasi and apple aphids was found. The cherry aphid is likely to be an important source of natural enemies that attack apple aphids early in the season. Significantly reduced numbers of ants associating with apple aphids in the intercropping habitat were found. Our results emphasize the importance of considering indirect interactions in the designing of pest management strategies.

Model fitting of the seasonal population dynamics of the soybean aphid, Aphis glycines Matsumura, in the field

The soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is one of the greatest threats to soybean production, and both trend analysis and periodic analysis of its population dynamics are important for integrated pest management (IPM). Based on systematically investigating soybean aphid populations in the field from 2018 to 2020, this study adopted the inverse logistic model for the first time, and combined it with the classical logistic model to describe the changes in seasonal population abundance from colonization to extinction in the field. Then, the increasing and decreasing phases of the population fluctuation were divided by calculating the inflection points of the models, which exhibited distinct seasonal trends of the soybean aphid populations in each year. In addition, multifactor logistic models were then established for the first time, in which the abundance of soybean aphids in the field changed with time and relevant environmental conditions. This model enabled the prediction of instantaneous aphid abundance at a given time based on relevant meteorological data. Taken as a whole, the successful approaches implemented in this study could be used to build a theoretical framework for practical IPM strategies for controlling soybean aphids.

Population dynamics of migrant wheat aphids in China's main wheat production region and their interactions with bacterial symbionts.

Sitobion miscanthi, Rhopalosiphum padi, and Schizaphis graminum are the three main pests in Chinese wheat-producing regions. In 2020, they are classified into the Chinese Class I list of agricultural diseases and pests, due to their severe harm to wheat plantings. S. miscanthi, R. padi, and S. graminum are migrant pests, and understanding their migration patterns and simulating their migration trajectories would improve forecasting and controlling them. Furthermore, the bacterial community of the migrant wheat aphid is also less known. In this study, we employed a suction trap to uncover the migration patterns of the three wheat aphid species in Yuanyang county, Henan province, during 2018 to 2020. And then the migration trajectories of S. miscanthi and R. padi were simulated using the NOAA HYSPLIT model. The interactions between wheat aphids and bacteria were further revealed by specific PCR and 16S rRNA amplicon sequencing. The results showed that the population dynamics of migrant wheat aphids was varied. Most of the trapped samples were identified to be R. padi, and S. graminum was the least collected sample. Typically, R. padi had two migration peaks in the 3 years, whereas S. miscanthi and S. graminum only exhibited one migration peak in 2018 and 2019. Moreover, the aphid migration trajectories varied over the years. Generally, the aphids originated from the south and migrated to the north. Herein, the infections of three main aphid facultative bacterial symbionts, Serratia symbiotica, Hamiltonella defensa, and Regiella insercticola, were detected in S. miscanthi and R. padi with specific PCR. Rickettsiella, Arsenophonus, Rickettsia, and Wolbachia were further identified with 16S rRNA amplicon sequencing. Biomarker searching indicated that Arsenophonus was significantly enriched in R. padi. Furthermore, diversity analyses showed that the bacterial community of R. padi had a higher richness and evenness than that of S. miscanthi. In conclusion, this study expands our knowledge about the migration patterns of aphids in the main wheat plant region of China and reveals the interactions between bacterial symbionts and migrant aphids.

Flower strips increase the control of rosy apple aphids after parasitoid releases in an apple orchard

AbstractMass releases of two parasitoid species, Aphidius matricariae and Ephedrus cerasicola, may provide an alternative measure to pesticides to control the rosy apple aphid Dysaphis plantaginea in organic apple orchards. As an exploratory study, we tested if the presence of flower strips between apple tree rows could improve the action of three early parasitoid releases––and of other naturally present aphid enemies––on the control of aphid colonies and the number of aphids per tree. Apple trees located at various distances from parasitoid release points were monitored in plots with and without flower strips in an organic apple orchard over two years, along the season of aphid infestation (March to July). Our case study demonstrated that the presence of flowering plant mixes in the alleyways of the apple orchard reduced the presence of D. plantaginea by 33.4%, compared to plots without flower strips, at the infestation peak date. We also showed a negative effect of increasing the distance to parasitoid release points on aphid control. However, our results at the infestation peak date suggest that the presence of flower strips could marginally compensate for the detrimental effect of increasing distance to the release point, probably by improving the persistence and dispersal capacities of natural enemies. Despite high variations in aphid population dynamics between years, we conclude that combining flower strips with early parasitoid releases in apple orchards is promising for biological control of the rosy apple aphid, although the method merits to be further refined.

Mitochondrial ND4 Gene as a Marker Trait for Studying Structure and Dynamics of Aphid (Hemiptera, Aphididae) Populations

Mitochondrial ND4 Gene as a Marker Trait for Studying Structure and Dynamics of Aphid (Hemiptera, Aphididae) Populations

Population Dynamics of Aphid, Aphis gossypii Glover on Bt and non-Bt Cotton and Correlation with weather Parameters

Investigations on the population dynamics of aphid Aphis gossypii Glover on Bt (G.Cot.Hy.8 BG II) and non-Bt (G.Cot.Hy.8) were carried out at Main Cotton Research Station, Navsari Agricultural University, Surat, Gujarat during the Kharif, 2020-21. The incidence of aphids initiated in the first week of July (27th SW) in Bt cotton hybrid and in the second week of July (28th SW) in non-Bt cotton hybrid and continued till the crop harvest in the second week of January (2nd SW) in both the hybrids. The peak activity of aphids was recorded during the third week of December (51st SW) in Bt as well as non-Bt cotton hybrid. In both Bt and non-Bt cotton, the aphid population had a significant negative correlation with morning relative humidity. There was a highly significant negative correlation with minimum temperature, evening relative humidity, rainfall, rainy days, and a positive correlation with sunshine hours.