The investigation on diversity of insect visitors and their role on Indian mustard was conducted at Agronomy Farm, S.K.N. College of Agriculture, Jobner during Rabi, 2023-24. During the study a total 20 insect species were found visiting mustard inflorescence, which belonged to 18 families of 8 different orders and further based on categorization, 5 insects were found as only nectar foragers, 6 as both pollen and nectar foragers, while 9 as casual visitors.

Indian mustard, diversity, pollen foragers, nectar foragers.

Indian mustard (Brassica juncea) is an important oilseed crop in India, known for its seeds rich in oil content. Rajasthan leads the country in   rapeseed-mustard production, contributing approximately 46 per cent of the total output. Alongside Rajasthan, states like Uttar Pradesh, Haryana and Madhya Pradesh play significant roles, collectively accounting for 77 per cent of the cultivation area and 82 per cent of production (Bansal and Kukkar 2020). In the 2023-24 period, rapeseed-mustard cultivation spanned 9,183 hectares, yielding 13,259 tonnes with a productivity rate of 1,444 kg/ha (Anonymous, 2024). Common insect pests affecting mustard crops include mustard aphid, leaf webber, flea beetle, painted bug and mustard sawfly (Srija et al., 2024). Although primarily self-pollinating, B. juncea benefits from insect-assisted cross-pollination, which can significantly improve both seed yield and quality. Understanding the diversity and behaviour of insect pollinators is essential for optimizing mustard cultivation. Effective pollinator identification and promotion can lead to enhanced crop productivity. A study recorded 88 insect species from 63 genera across 31 families and nine orders visiting mustard blooms. Among these, insects from the Hymenoptera order were predominant, with Apis cerana and A. mellifera showing higher abundance through scan sampling methods (Devi et al., 2017).

An attempt was made in identifying other insect visitors (apart from mustard aphid) and their role in Indian mustard (variety-Giriraj) inflorescence during Rabi, 2023-24 in five selected plots (3 × 2.4 m2). Weekly observations were recorded from the flower initiation phase and continued till 90 per cent flowering on 10 randomly selected plants from each experimental plot at two hours interval from 08:00 hrs to 16:00 hrs. Based on the activity these insects were further categorized into pollen foragers, nectar foragers and casual visitors, respectively. 

Table 1 illustrates the distribution of insect species from eight different orders observed visiting mustard inflorescences. Hymenoptera was the most prevalent order, accounting for 30 per cent of the total insect population with six species, followed by Diptera at 25 per cent with five species. Hemiptera constituted 15 per cent with three species, while Coleoptera represented 10 per cent with two species. Thysanoptera, Odonata, Neuroptera and Lepidoptera each contributed 5 per cent with one species, reflecting a diverse assemblage of insect visitors. These results are consistent with previous studies conducted by Neha et al. (2014); Pudasaini et al. (2015); Nagpal (2016); Abrol and Bajiya (2017); Devi et al. (2017); Giri et al. (2018); Das and Jha (2018); Poonam et al. (2022); Rao et al. (2022); Bijarniya et al. (2024); Prajula et al. (2024), who also identified Hymenoptera as the most dominant insect order in mustard ecosystems.

A total of 20 insect species from 18 families and 8 different orders were observed (Table 2). Among them, six species (Rock bee, little bee, syrphid fly, bumble bee, sweat bee and green lacewing) were identified as both pollen foragers (PF) and nectar foragers (NF). Five species, which include one Lepidoptera and four species from order Diptera as only nectar foragers (NF). Casual visitors (CV) included nine species, such as ladybird beetle, wasp, tingid bug, sap beetle, banded thrips, dusky cotton bug, black ant, shield bug and dragonfly. Sankarsan et al. (2014) findings revealed that four out of six hymenopteran species that visit mustard flowers feed for both pollen and nectar, whereas two species only forage for nectar. Three species of dipterans and all lepidopterans were found to be exclusively nectar foragers. The remaining orders, Coleoptera, Odonata and Hemiptera, were described as casual visitors to the mustard inflorescence; these findings are consistent with the present findings.

This diversity highlights the significant roles played by various insect families in pollination and their interactions with plants, with Hymenoptera being dominant among both pollen and nectar foragers. 

Table 1: Predominant insect orders present in Indian mustard ecosystem.

Table 2: Insect species (Pollen foragers, Nectar foragers and Casual visitors) present in Indian mustard ecosystem.

The study highlights the importance of insect visitors in Indian mustard cultivation. Future research should focus on enhancing pollinator conservation, evaluating pollination efficiency and developing eco-friendly pest management strategies. Additionally, studies on climate impacts and insect behaviour can help optimize crop productivity and promote sustainable agricultural practices.

T. Revanth Sri, R.K. Meena, Akhter Hussain, B.L. Jat, S.L. Sharma and J.K. Bana  (2025). Insect visitors in Indian Mustard [Brassica juncea (L.) Czern and Coss]: Diversity and their Role. Biological Forum, 17(2): 35-38.