Studies on Tomato (Solanum lycoperisicum L.) major insect pests seasonal incidence and their correlation with weather parameters

Introduction

Tomato (Solanum lycopersicum L.), belonging to the family Solanaceae, is one of the major vegetable crops with high economic value grown across the world (Kumar et al., 2020) [6] . It is grown under both open-field and protected cultivation systems for fresh consumption as well as for processing into products such as juice, paste, puree, sauces, soups and ketchup (Maurya et al., 2025) [8] . Owing to its high nutritional and medicinal value, the tomato occupies a prominent place among vegetable crops and ranks second after the potato in India. The fruits are an excellent source of vitamins A, B-complex and C, minerals such as calcium, phosphorus and iron, and the antioxidant lycopene, which is known for its role in reducing the risk of several chronic diseases (Rasheed et al., 2022) [15] . The crop is believed to have originated in South America, while its cultivated forms were developed in Mexico before spreading to different parts of the world (Knapp and Peralta, 2016) [5] . In India, tomato is widely cultivated as one of the main vegetable crops, contributing significantly to the national economy. It grows best under moderate climatic conditions with an optimum temperature range of 21-24°C. However, the changes in the climatic conditions affect its growth and make it easily susceptible to several insect pests (Deb and Bharpoda, 2017) [3] . Although advancements in agricultural technologies and the use of protected structures have enhanced production, insect pests remain the major constraints hampering tomato yield and quality. The major insect pests include tomato fruit borer (Helicoverpa armigera), whitefly (Bemisia tabaci), leafhopper (Amrasca devastans), thrips (Scirtothrips dorsalis) and serpentine leaf miner (Liriomyza trifolii) (Pratheek, 2023) [13] , which attack tomato plants throughout the growing season and cause severe quantitative and qualitative losses. Among these, the tomato fruit borer is known to cause the most damage to the crop, as the larvae feed on foliage, flowers and developing fruits. They even make fruits unmarketable once they start boring into the fruits. Yield losses due to H. armigera range from about 18 to 80 per cent depending upon pest intensity, crop stage and dominant climatic conditions (ul Haq and Ismail, 2026) [17] . Similarly, sucking pests including whiteflies, aphids, thrips and leafhoppers also cause direct damage by feeding on the sap and also act as vectors for the spread of viral diseases, reducing the in the crop productivity. The prevalent weather conditions, including temperature, relative humidity, rainfall, photoperiod and crop phenology, largely influence the occurrence and abundance of insect pests on tomato. For the prediction of pest outbreaks and the development of effective integrated pest management (IPM) strategies, a thorough understanding of the seasonal incidence and population dynamics of these pests is important (Mengasha et al., 2025) [9] . Regular monitoring of pest populations in the prevailing weather conditions is necessary for determining the proper time for carrying out management practices and reducing the usage of pesticides. The overuse of synthetic insecticides has led to severe damage to the environment, humans and animals, including destruction of natural enemies, development of insecticide resistance and presence of pesticide residues in fruits (Barathi et al., 2024) [1] . Therefore, there is an urgent need for the adoption of sustainable and scientifically built pest management methods based on monitoring of pest incidence rather than repetitive pesticide applications. In light of this need, studies on seasonal incidence help farmers to identify peak activity periods of economically important pests for the timely application of control measures, especially at the most vulnerable stages of pest development (Mrosso et al., 2023) [10] . Moreover, such information plays a crucial role under changing climatic conditions, where the variations in temperature and humidity alter the pest behaviour, their survival and distribution. Despite being of great economic importance, complete information on the seasonal incidence of major insect pests of tomato under different agro-climatic conditions still remains limited. Therefore, the present investigation was undertaken to study the seasonal incidence of major insect pests of tomato and to determine their relationship with prevailing weather parameters. The findings of the study will contribute to a better understanding of pest population dynamics and provide a scientific basis for developing timely, economical and environmentally sustainable pest management strategies for tomato cultivation.

Materials and Methods

Experimental Site

The field experiment was conducted during the tomato cropping season of 2025 (February to June) at the Research Farm, Faculty of Agriculture, Maharishi Markandeshwar (Deemed to be University), Mullana-Ambala, Haryana.

Procurement of seed

The seeds of the tomato variety Heemasohna were procured from Bhatia Seeds and Pesticides store, Shahabad.

Experimental details

The experiment was laid out in a Randomized Block Design (RBD) comprising ten treatments (Table 1; Fig 1) with three replications. Tomato variety Heemasohna was transplanted in February 2025 at a spacing of 60 × 45 cm on raised beds. All recommended agronomic practices were followed uniformly except for plant protection measures.

Observations recorded

Observations on the seasonal incidence of major insect pests, namely tomato fruit borer (Helicoverpa armigera), whitefly (Bemisia tabaci), leafhopper (Amrasca devastans) and serpentine leaf miner (Liriomyza trifolii), were recorded at weekly intervals from transplanting to final harvest by randomly selecting and tagging five plants. The population of each pest was recorded using standard sampling methods and the observations were correlated with prevailing weather parameters to study their seasonal incidence and population dynamics.

Data Analysis

The experimental data were subjected to correlation using OPSTAT software.

Results

Seasonal incidence of major insect pests 3.1.1 Whitefly (Bemisia tabaci)

The population of whitefly first appeared during the 8 th SMW with a mean population of 0.13 whiteflies per leaf (Table 1; Fig 1). Thereafter, the population increased gradually with the advancement of the crop growth stage and favourable weather conditions. The whitefly population reached its maximum of 4.56 whiteflies per leaf during the 16 th SMW when the maximum and minimum temperatures were 40.29 °C and 24.14 °C, respectively, with an average relative humidity of 50.36%. Subsequently, the population declined gradually to 3.75 and 3.21 whiteflies per leaf during the 17 th and 18 th SMW, respectively.

Serpentine leaf miner (Liriomyza trifolii)

The incidence of serpentine leaf miner was first recorded during the 8 th SMW with a mean population of 0.87 larvae per plant (Table 1; Fig 1). The pest population increased progressively throughout the crop season and attained its peak population of 4.85 larvae per plant during the 16 th SMW under prevailing weather conditions of 40.29 °C maximum temperature, 24.14°C minimum temperature and 50.36% average relative humidity. Thereafter, the population declined to 3.98 larvae per plant during the 17 th SMW and further decreased to 2.81 larvae per plant during the 18 th SMW.

Tomato fruit borer (Helicoverpa armigera)

The fruit borer (Helicoverpa armigera) was absent up to the 9 th SMW and its first appearance was observed during the 10 th SMW with a mean population of 0.89 larvae per plant (Table 1; Fig 1). The larval population increased steadily from 1.12 larvae per plant during the 11 th SMW to 3.76 larvae per plant during the 15 th SMW. The highest population, 3.94 larvae per plant, was recorded during the 16 th SMW under high-temperature conditions. Thereafter, the population declined gradually to 3.62 and 3.38 larvae per plant during the 17 th and 18 th SMW, respectively.

Leafhopper (Amrasca devastans)

The leafhopper population first appeared during the 8 th SMW with a mean population of 3.20 leafhoppers per plant (Table 1; Fig 1). The population increased continuously during the succeeding weeks and reached a peak of 8.60 leafhoppers per plant during the 14 th SMW, when the maximum temperature was 36.86°C, the minimum temperature was 21.86°C and the average relative humidity was 44.57%. Thereafter, the population gradually declined to 7.80, 6.70, 6.10 and 5.30 leafhoppers per plant during the 15 th , 16 th , 17 th and 18 th SMW, respectively.

Correlation of major insect pests of tomato with weather parameters

The correlation analysis indicated that the population of major insect pests of tomato was positively influenced by the prevailing weather parameters (Table 2; Fig 2). Whitefly exhibited a highly significant positive correlation with maximum temperature, minimum temperature and average relative humidity, with correlation coefficients of 0.918, 0.968 and 0.923, respectively. Similarly, the population of serpentine leaf miner showed highly significant positive correlations with maximum temperature, minimum temperature and average relative humidity, recording correlation coefficients of 0.887, 0.938 and 0.911, respectively. Tomato fruit borer also exhibited a highly significant positive association with all the weather parameters, with correlation coefficients of 0.942 for maximum temperature, 0.964 for minimum temperature and 0.890 for average relative humidity.

Leafhopper population showed a significant positive correlation with maximum temperature, recording a correlation coefficient of 0.676, while it exhibited highly significant positive correlations with minimum temperature and average relative humidity, with correlation coefficients of 0.752 and 0.756, respectively. These findings indicate that increasing temperature and favourable relative humidity played an important role in the multiplication and seasonal abundance of major insect pests of tomato and may be useful for forecasting pest outbreaks and planning timely pest management strategies.

Discussion

The present investigation revealed that the seasonal incidence of major insect pests of tomato was greatly influenced by prevailing weather conditions and crop growth stage. Whitefly, leaf miner and leafhopper first appeared during the 8 th SMW, whereas fruit borer infestation commenced during the 10 th SMW. The populations of all pests increased gradually and reached their peak during the 14 th to 16 th SMW before declining towards crop maturity. Whitefly and leaf miner attained their highest populations during the 16 th SMW, while leafhopper reached its highest population during the 14 th SMW and fruit borer during the 16 th SMW. Similar findings for whitefly were reported by Padhi et al. (2017) [10] and Radhika et al. (2018) [14] . The seasonal incidence of leaf miner observed in the present study is in agreement with the findings of Dibbad et al. (2020) [4] . The present observations on fruit borer are in conformity with the reports of Chakraborty et al. (2012) [2] , who also observed peak infestation during the middle reproductive stage of the crop. The correlation analysis indicated that the population of major insect pests was significantly influenced by weather parameters. Whitefly, leaf miner and fruit borer exhibited highly significant positive correlations with maximum temperature, minimum temperature and average relative humidity, whereas leaf hopper showed a significant positive association with maximum temperature and highly significant positive correlations with minimum temperature and average relative humidity. These findings suggest that increasing temperature, coupled with favourable relative humidity, created suitable conditions for pest multiplication and seasonal abundance. Similar findings were reported by Sharma et al. (2017) [16] , who observed a positive relationship between temperature and the population dynamics of major tomato insect pests. Moreover, whitefly multiplication is found to be favoured by higher temperatures and a significant positive association between temperature and whitefly incidence has also been reported (Latif and Akhter, 2013; Pavan, 2021) [7,12] . Similarly, an increase has also been observed in Helicoverpa armigera. These findings indicate the significance of weather parameters, particularly temperature and relative humidity, in influencing the seasonal pest occurrence and their utilization in forecasting pest outbreaks and the timely implementation of integrated pest management practices in tomato cultivation.

Conclusion

The study showcased the close association of the incidence and abundance of major insect pests in tomato with predominant environmental conditions and crop growth stage. Among the pests observed, the highest populations of whitefly, leaf miner and fruit borer were recorded during the 16 th SMW and that of leafhopper during the 14 th SMW. Weather parameters, mainly the maximum and minimum temperatures and average relative humidity, showed a significant positive influence on pest population dynamics. These findings, thus, underscore the importance of predicting pest outbreaks and the adoption of timely, effective and sustainable pest management strategies in tomato cultivation via continuous pest surveillance and weather-based monitoring.

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