Pulses are key components of Indian food, cultivated on 35 million hectares, contributing 37% to the global area and 29% to total production. The country’s pulse requirement is projected to be 32 million tonnes by 2030 and 39 million tonnes by 2050, with a 2.2% annual growth rate (Singh et al., 2018). Blackgram and greengram are important short-duration pulses grown under rainfed, irrigated and rice fallow conditions. In Tamil Nadu, blackgram is cultivated on 40.02 million hectares with 26.31 million tonnes produced and 657 kg/ha productivity (Kavisri and Sunderraj, 2025). Greengram is grown on 48.52 million hectares with 26.48 million tonnes produced and 546 kg/ha productivity (Anonymous, 2022).
       
Pulses productivity remains below global average in India. Among yield limiting factors, insect pest infestation is a major concern for farmers, especially in short duration pulses. The sucking insect pests, whitefly Bemisia tabaci, aphid Aphis craccivoraand leafhopper Emposca kerri, are important concerns apart from borers. These insects transmit yellow mosaic, leaf crinkle and leaf curl viral diseases, which reduce yield and quality. Among Lepidopterans, spotted pod borer Maruca vitrata, gram pod borer Helicoverpa armigera, plume moth Exelastis atomosa and blue butterflies Lampides boeticus are economically important. Justin et al., (2015) revealed that insect pests cause 30% yield loss in blackgram and greengram.
       
Farmers primarily apply insecticides for pest management. Overreliance leads to issues like resistance and resurgence in target and nontarget insect pests. Insecticides persist in soil, plants and harvestable produce (Ahouangninou et al., 2012; Malarkodi et al., 2021). Sustainable pest management aims to reduce insecticide usage. Seed treatment with insecticides and biologicals reduces early season spraying (Taylor et al., 2001). These treatments reduce insect pests early without harming natural enemies in the crop ecosystem (Krauter et al., 2001).
       
Efficacy of seed treatment insecticides against pulses sucking insect pests has been reported by few researchers (Alekya et al., 2022; Chaudhari et al., 2024). Studies on entomopathogenic fungi and botanicals as seed treatments in short duration pulses are scanty. Laboratory investigations on seed treatment insecticides against sucking insect pests in short duration pulses are limited in India and these studies will indicate the suitability of insecticides, botanicals and microbial control agents as seed treatments. The present investigation studied the efficacy of three chemical seed treatment insecticides, two EPFs and one botanical as seed treatments in two short duration pulses. 

Insect cultures (Aphid A. craccivora and whitefly B. tabaci)
 
Cowpea seeds Co (CP)7 were grown in polyvinyl pots containing soil, sand and FYM in a 1:1:1 ratio. Plants were raised inside insect-proof cages to prevent insect damage and irrigated using flowerpots. A. craccivora from cowpea fields were released into these plants for development. Simultaneously, cowpea plants were raised in another insect cage in a staggered manner and provided to aphid cultures as needed. These populations were maintained for three generations and used for laboratory investigations. Similarly, B. tabaci were mass multiplied using brinjal (Simran hybrid) seedlings. Both aphid and whitefly cultures were maintained at 32±2°C, 60-70% relative humidity and under natural photoperiod conditions.
 
Pot culture experiments
 
Pot culture experiments were conducted at the Department of Agricultural Entomology, TNAU, Coimbatore. Blackgram (Co6) and greengram (Co8) seeds were sown in polyethylene pots with growing media. Seeds were treated with seed treatment insecticides, EPF and botanicals and shade-dried for 30 min (Table 1). Seeds were sown at 3 seeds/pot in ten pots and replicated three times, using 30 pots for each treatment. Pots were kept inside insect-proof nets and irrigated using flower pots. Untreated seeds under the same conditions served as a control. Foliar spray of thiamethoxam was applied on the 5^th day after plant emergence using a garden sprayer.


       
Leaves from seed-treated and untreated control plants were collected on the 7^th, 14^th and 21^st days after germination and washed with distilled water. These leaves were kept in petri dishes with moistened filter paper. Aphids from laboratory populations were released to dishes @ 5 aphids/plant and replicated three times @ 10 petri dishes/replication. In total, 150 aphids per treatment were used to assess seed treatment efficacy. Foliar spraying of thiamethoxam (T10) was performed 5 days after emergence and laboratory assessment was conducted as described earlier. Efficacy against whiteflies was also studied simultaneously. Mortality data was collected up to 72 hours for insecticide treatment and up to 96 hours for EPF and botanicals.
 
Field experiments
 
Field experiments were conducted at the Department of Pulses, TNAU, Coimbatore (11.025526 N; 76.929674 E) and farmers’ fields in Pariyapattipudur, Dharmapuri (11.994872 N; 78.417644 E), in a 0.2 ha area per crop. Seeds were treated as described above for sowing. Each treatment was sown in 60 m² plots (10×6 m). Land preparation and agronomic practices followed the recommendations of the Tamil Nadu Agricultural University. Seeds were sown at 30x10 cm spacing in ridges and furrows. The incidence of sucking insect pests (aphids, whiteflies, leafhoppers and thrips) and natural enemies was recorded weekly for three weeks on five randomly selected plants per treatment and expressed as numbers per leaf.
 
Data analysis
 
The mean of aphid and whitefly mortality data collected for each replication in the laboratory bioassays was calculated. Aphid, whitefly, thrips, leafhopper and natural enemies details collected from the field experiments were averaged for each replication and analyzed using Analysis of Variance (ANOVA) with Statistical Analysis System (SAS) version 13.0. The cumulative means of individual sucking insect and natural enemy populations were estimated for each location in the field experiments. The means were subjected to arcsine and square root transformations, as needed. Tukey’s Honestly Significant Difference (HSD) test was used to differentiate the mean significance (P<0.05). To examine the interrelationships between pest populations and natural enemies under different treatments, Pearson’s correlation coefficients were computed using numerical field data for each season. The resulting correlation matrices were transformed into a long format using the reshape2 package in R (Wickham, 2007).

Laboratory investigations showed seed treatment efficacy decreased with crop age. Chemical seed treatment insecticides were more effective than entomopathogenic fungi and botanicals. In greengram and blackgram, seed treatment exhibited a similar trend. Among chemical insecticides, thiamethoxam 30 FS was most effective, followed by imidacloprid 600 FS and cyantraniliprole 19.8%+thiamethoxam 19.8% FS in blackgram, while the trend varied in greengram. Cyantraniliprole 19.8%+ thiamethoxam 19.8% FS was the second most effective for greengram. Among EPF, M. anisopliae 10 ml/kg was most effective, followed by M. anisopliae 5 ml/kg and B. Bassiana 5 ml/kg and 10 ml/kg in both crops (Fig 1 and 3). Similar efficacy was observed against whiteflies with chemical insecticides in laboratory investigations (Fig 2 and 4). Higher doses of M. anisopliae showed no significant difference against whiteflies under laboratory conditions. Laboratory tests confirmed that Azadirachtin 1% at both doses as seed treatment was least effective. Laboratory and field investigation confirmed that B. bassiana seed treatment in maize effectively reduces the fall armyworm Spodoptera frugiperda infestation (Kuzhuppillymyal-Prabhakarankutty et al., 2021).








       
Seed treatment insecticides did not significantly influence stem fly infestation in blackgram. All seed treatment combinations recorded lower infestation than the untreated control at both locations up to 15 DAS. In the Coimbatore field experiment, cyantraniliprole 19.8%+ thiamethoxam 19.8% FS was found to be statistically significant in reducing the stem fly population at 21 DAS. Whitefly, aphid and leafhopper infestations showed almost similar trends at both experimental locations in blackgram.  The sucking insect pest population was lowest in thiamethoxam 30FS treated plots at both experimental locations up to 15 DAS. This was followed by cyantraniliprole 19.8% + thiamethoxam 19.8% FS and imidacloprid 600 FS. The seed treatment insecticides effectively reduced the population of sucking insect pests during the first fortnight, which is a crucial period of crop growth (Table 2).


       
In greengram, the order of efficacy of seed treatment insecticides was thiamethoxam 30 FS > cyantraniliprole 19.8%+thiamethoxam 19.8% FS > imidacloprid 600FS. The botanicals were least effective in both crops as seed treatment (Table 3). Panduranga et al., (2011) and Patel et al. (2012) revealed that thiamethoxam 70 WS and imidacloprid 70 WS reduce the whitefly population in cowpea and mungbean, respectively. Mahalakshmi et al., (2018) revealed that seed treatment followed by thiamethoxam 25 WG or acetameprid 20 SP spray effectively reduced thrips and whiteflies in greengram. Anusha et al., (2016) revealed similar results for 600 FS @ 10 ml/kg seed treatment in cowpea. In the present study, imidacloprid 600 FS also reduced the sucking insect pest population up to 21 DAS.


       
Improved growth parameters due to seed treatment have been recorded by several researchers (Herbert et al., 2008; Narayanan et al., 2017; Devi et al., 2021). Visual observations in the field experiments revealed that crop growth was good in seeds treated with insecticides, followed by entomopathogenic fungi. The endophytic influence of EPF has been reported by many researchers (Monisha et al., 2025). In the present investigation, the population of sucking insect pests increased after 21 DAS. Seed treatment with cyantraniliprole 19.8%+thiamethoxam 19.8% FS @ 4 ml/kg + spraying of acephate @ 3 g/l at 20 and 40 days after germination reduced the aphid, whitefly and thrips populations in greengram (Alekya et al., 2022). The combination seed treatment insecticide was second in the order for most of the sucking insect pests in blackgram and greengram.  
       
Among the eleven treatments evaluated by Chaudhari et al., (2024), imidacloprid 48 FS seed treatment and spray with flubendiamide 48 SC recorded the lowest number of sucking pests and borer incidence, apart from the highest yield and profit in greengram. Imidacloprid 600 FS @ 10 ml/kg and thiamethoxam 30 FS @ 5.7 ml/kg seed treatment in blackgram recorded the lowest sucking pest population up to 30-35 DAS (Shobharani et al., 2019). The results of the present study are consistent with these findings. As we designed the experiments exclusively for early season sucking insect pest incidence in blackgram and greengram, we did not apply a second round of insecticides in the present investigation.
       
Although the foliar application of systemic insecticides reduces the sucking insect pest population, timely application is crucial to check population buildup in the field. Moreover, the labor cost involved in seed treatment is lower than that of foliar spray. Early protection up to one week is crucial for healthy crop growth because a sudden increase in the sucking pest population reduces growth. In addition, disease-transmitting whiteflies must be curtailed during the first week of sowing to reduce the prevalence of viral diseases. Bony et al., (2017) revealed that seed treatment with imidacloprid and thiram reduced the incidence of viral diseases in soybean.
       
M. anisopliae ICIPE 20 inoculation in beans resulted in lower infestation of stem maggots Ophiomyia phaseoli  (Mutune et al., 2016). The ability of entomopathogenic fungi to produce secondary metabolites inside the plant system may be the main reason for their negative effects on herbivore population (Jaber and Ownley, 2018). M. anisopliae and B. bassiana seed treatment also showed decreased insect pest incidence compare to the untreated control. Native EPF strains may have greater potential than general strains (Monisha et al., 2025). Identifying native strains with induced resistance capabilities enhances their potential as seed treatment candidates. 
       
Coccinellid and spider populations were more abundant in the untreated control, followed by botanicals, EPF and insecticides (Supplementary Table 1 and 2). The EPF-treated plots recorded a higher number of coccinellids and spiders than the insecticide-treated plots. Heatmap analysis revealed distinct patterns of associations between pest populations and natural enemies across treatments and locations (Fig 5 and 6). Whitefly, aphid and leafhopper populations showed high positive correlations in both blackgram and greengram ecosystems, suggesting that they occurred concurrently under similar field conditions. In contrast, the numbers of coccinellids, hymenopterans and spiders were negatively correlated with these major sucking pests, indicating active predatory management. Swarupa et al. (2019) recorded a lesser number of coccinellids and spiders in the chemical insecticide treated plots compared to the untreated control plots in cowpea. Resource availability influences the abundance of natural enemies in crop ecosystems. The sucking insect population was the lowest in the insecticide-treated plots compared to those treated with EPF and botanicals. Studies on the endophytic capabilities of EPF in pulses are scarce. These studies will provide further insights into the role of EPFs as seed treatment and growth promoters in short-duration pulses.

Short duration pulses are prone to sucking pest infestations during the early stages, adversely affecting productivity. Disease-transmitting vectors must be controlled in the early stages, with minimum expenditure, to avoid viral disease occurrence. Among the components evaluated against the sucking insect pests, viz., aphid, whitefly and leaf hopper, chemical seed treatment insecticides were found to be more effective, followed by entomopathogenic fungi. Azadirachtin was least effective against the early stage sucking insect pests in both blackgram and greengram. The natural enemies showed a negative correlation with sucking insect pests across the treatments in both locations, indicating that seed treatment insecticides do not have an impact on the natural enemies. The present study revealed that chemical seed treatment insecticides can be used for early season sucking insect pest management in short-duration pulses. Entomopathogenic fungi can be employed as seed treatment agent in organic farming systems.  

The authors acknowledge the Department of Agricultural Entomology, Centre for Plant Protection Studies, Tamil Nadu Agricultural University, Coimbatore and the Department of Pulses, Centre for Plant Breeding and Genetics, Tamil Nadu Agricultural University, Coimbatore, for providing the necessary facilities to conduct this study. The authors are also grateful to Mr. Venketasan, Farmer, Pariyapattipudur, Harur for providing land and labour to conduct the field experiments. 
 
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The views and conclusions expressed in this article are solely those of the authors and do not necessarily represent the views of their affiliated institutions. The authors are responsible for the accuracy and completeness of the information provided but do not accept any liability for any direct or indirect losses resulting from the use of this content.
 
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