Abundance and foraging behavior of native insect pollinators and their effect on mustard (Brassica juncea L.)

Abstract

A field experiment was carried out in Gazipur, Bangladesh to find out the abundance and behavior of native insect pollinators and their impact on the yield and seed quality of mustard (Brassica juncea L.). Total 8 species of insects under 8 different families in 3 orders were found as pollinator and their abundance ranged from 0.5 to 6.6/30 sweeps. The pollinator insects revealed statistically higher abundance compared to pest, predator and other category. The pollinators were most abundant at 11.0 hrs of the day and differed in their landing duration on flower. Ant and cabbage butterfly stayed statistically similar and longer time (24.1 and 23.5 sec., respectively). The highest yield (994.3 kg/ha) was obtained from insect managed pollination treatment followed by open (759.7 kg/ha) and enclosed condition (272.3 kg/ha). Insect pollination revealed higher percentage of germination, t100-seed weight, per cent oil and protein content but the results did not differ statistically.

Mustard plants distant from forest fragments receive a lower diversity of flower-visiting insects

“…Therefore, even though Apis-bees commonly dominate Brassica spp. fields in Asian regions (Bajiya & Abrol, 2017;Devi et al, 2017;Mandal et al, 2018;Mishra et al, 1988;Pudasaini et al, 2015;Stanley et al, 2017), we found that some solitary bee species can also be relevant in mustard crops in Nepal. As a result, we suggest that local farmers could modify their agricultural practices to preserve the regional insect diversity especially those bee species with solitary lifestyles.…”

“…The dominance of Apis-bees, mainly A. mellifera, found in other studies seems to be attributable in part to the presence of hives near mustard crops (Bajiya & Abrol, 2017;Devi et al, 2017;Mandal et al, 2018;Mishra et al, 1988;Pudasaini et al, 2015;Stanley et al, 2017). Nevertheless, in our study, we did not evaluate the presence of apiaries around our sampling units.…”

“…Our findings demonstrate that a large diversity of insects as bees and, to a lesser extent, flies and butterflies, visit the (Bajiya & Abrol, 2017;Devi et al, 2017;Mandal et al, 2018;Mishra et al, 1988;Pudasaini et al, 2015;Stanley et al, 2017). Flies and butterflies may also pollinate mustard crops, but their contribution is negligible (Bajiya & Abrol, 2017;Mishra et al, 1988;Pudasaini et al, 2015;Stanley et al, 2017).…”

“…However, mass flowering crops may, at least temporarily, provide abundant food resources for flower-visiting insects (Diek€ otter, Peter, Jauker, Wolters & Jauker, 2014). For example, mustard fields (e.g., Brassica campestris, Brassica juncea, Brassica napus) are mass flowering crops that are quite attractive for a large diversity of generalist insects (Bajiya & Abrol, 2017;Devi et al, 2017;Mandal, Amin, Rahman & Akanda, 2018;Mishra, Kumar & Gupta, 1988;Pudasaini, Thapa, Chaudhary & Tiwari, 2015;Stanley, Sah & Subbanna, 2017). As with most Brassica spp., the morphology of mustard flowers (open) makes it easy for multiple insects like flies (Diptera), butterflies (Lepidoptera), wasps and bees (Hymenoptera) to feed from them (Bajiya & Abrol, 2017;Devi et al, 2017;Mandal et al, 2018;Mishra et al, 1988;Pudasaini et al, 2015;Stanley et al, 2017).…”

“…Therefore, even though mass flowering crops, such as mustard, may be pollinated by all of the insect groups mentioned above, they are particularly favoured by social bees, such as Apis mellifera, A. cerana, A. dorsata and A. florea, as they are dominant in such ecosystems once they nest or are managed near such crops (Bajiya & Abrol, 2017;Devi et al, 2017;Mandal et al, 2018;Mishra et al, 1988;Pudasaini et al, 2015;Stanley et al, 2017). The solitary bees and, to a lesser extent, flies and butterflies, have a similar role as Apis-bees (Bajiya & Abrol, 2017;Devi et al, 2017;Mandal et al, 2018;Mishra et al, 1988;Pudasaini et al, 2015;Stanley et al, 2017). However, Apisbees may forage over wider distances (revised by Abou-Shaara, 2014).…”