The Use of Honeybee Hives May Boost Yields of Some Crops in Nepal

Many pollination-dependent crops worldwide need bees for the highest productivity. If the crops are not pollinated, a pollination deficit will result. Consequently, low yields of fruit set and seed set of cultivated plants may be expected. Here, we evaluated how pollination with honeybee (Apis mellifera) hives may affect the production of the bittergourd (Momordica charantia), buckwheat (Fagopyrum esculentum), and mustard (Brassica campestris) in tons or quintal per hectare in Nepal. Our experimental design involved three treatments in blocks within selected areas: (i) the effect of the honeybees alone (caged with beehives), (ii) free insect access under natural field conditions, and (iii) blocks restraining insect access (caged without beehives). We also assessed the flower visiting insects within crops using pan traps and identifying insect orders. We found that the productivity of bittergourd, buckwheat, and mustard significantly increased in the treatments with beehives inside the cage. To a lesser extent, the treatment with free access to the flying insects enhanced the production of the selected crops. Proportionally, Hymenoptera (mainly bees) was the most common taxon within bittergourd, buckwheat, and mustard crops, followed by Diptera and Lepidoptera. Hence, the provision of beehives in cultivated areas such as those evaluated here could be considered as a complementary strategy for supporting the long-term productivity of these crops in Nepal.

Assessing the effectiveness of honey bee pollinators for cultivated blueberries in South Africa

Globally, agricultural crops are often dependent on insect pollination. Blueberries are an example of such a crop and owing to their proposed health benefits they are grown around the world, including locations where their native bumble bee pollinators do not occur. In the absence of bumble bees, blueberry pollination in South Africa and many other parts of the non-native, commercial range is performed primarily by honey bees. Despite this, the effectiveness of honey bee pollination on blueberries remains understudied. This study determined the effect of honey bee pollination on components of fruit yield (fruit set and mass) of five blueberry varieties that are extensively planted in South Africa. For each variety, two metrics were calculated: 1) the benefit of bees — a comparison of fruit yields after exposure to honey bees and fruit yields after honey bee exclusion, 2) the pollination deficit — the difference in yield between hand pollination (maximum yield potential) and yields after exposure to honey bee pollinators. Honey bee pollination consistently resulted in improved yields, although the magnitude of this improvement (i.e., the benefit of bees) was dependent on the variety considered. Similarly, the pollination deficit also varied considerably across varieties and while some varieties appeared to perform close to maximum potential (small pollination deficit), others yielded well below their maximum potential under honey bee pollination. This study demonstrates that honey bees are functional pollinators of blueberries in areas where native blueberry pollinators are absent. However, in such areas, it is important that special focus be given to selecting blueberry varieties that perform well with honey bees as their sole pollinator. Further research is necessary to determine how the pollination deficit of blueberry varieties can be decreased as well as how to increase the effectiveness of honey bee pollination.

Utilization of Indian Dammar Bee (Tetragonula iridipennis Smith) as a Pollinator of Bitter Gourd

An experiment was conducted to determine the pollination deficit in bitter gourd (<em>Momordica charantia</em> L.) and the effect of the use of Indian dammar bee as pollinator on the yield. Diverse native visitors were recorded during the blooming period. Among those honeybees, stingless bee, solitary bees, and butterflies are legitimate visitors; all of them showed a selective preference for male flowers (flower sex type selection index ranged from 0.41 to 0.62). The plant species showed a pollination deficit in nature (coefficient of pollination deficit, D = 0.20), resulting in low fruit set in an open-pollination system. However, the value was significantly increased by the supplementary pollination services of a managed dammar bee colony. Furthermore, the quality of the fruits also improved in hand-pollinated and managed bee-pollinated systems in comparison to an open pollination system. Therefore, it is generally recommended that farmers use Indian dammar bee colonies in their agricultural land to increase the quantity and quality of the yield of bitter gourd.

Pollination Strategies to Improve Fruit Set in Orchards of ‘Manzanilloʼ Olive in a Nontraditional Producing Country, Mexico

In countries new to producing ‘Manzanillo’ olive trees (Olea europaea), free cross-pollination is often insufficient to obtain high levels of fruit set. An appropriate pollination design is therefore essential to ensure a timely, abundant, and compatible pollen supply. With a view to determining whether a pollination deficit exists in a nontraditional olive area such as the northern Mexico, pollination experiments were carried out in two consecutive seasons in both a monovarietal and a multivarietal Manzanillo orchard, where Sevillano, Barouni, Picual, Pendolino, Mission, Nevadillo, and Frantoio trees were growing nearby. The pollination treatments were self-, open, and cross-pollination with ‘Barouni’ and ‘Sevillano’ pollen, the latter only in the multivarietal orchard. The results confirmed the full self-incompatible condition of ‘Manzanillo’. Open-pollination did not improve fruit set in the monovarietal orchard, but it did so significantly in the multivarietal plot, where fruit set levels under open-pollination matched those of cross-pollination. Lower pollen adhesion, as well as occasional decreased germination, and reduced and delayed pollen tube growth were observed under self-pollination, highlighting self-incompatibility reactions. The reduction in fertilization rates led to low fruit set under self-pollination. Positive effects of open- and cross-pollination treatments were also noted on fruit weight (despite higher crop loads) and pulp-to-pit ratios. A strategic plantation design, including appropriate pollinizers in the right number and position, is therefore suggested for increasing ‘Manzanillo’ fruit quality and yield in Mexico. Both ‘Barouni’ and ‘Sevillano’ served as efficient pollinizers for ‘Manzanillo’, although we recommend ‘Barouni’ as a more efficient because the bloom periods of them matched that of ‘Manzanillo’

Cross-pollination Enhances Macadamia Yields, Even With Branch-level Resource Limitation

Macadamia is partially self-incompatible and cross-pollination is considered important to improve yields. However, questions remain regarding the importance of self- vs. cross-pollination, and subsequently whether managed pollinators are useful in commercial orchards. Pollinators play a key role in cross-pollination, but for self-pollination, the protandrous florets might also benefit from the movement of potentially more viable self-pollen among florets, racemes, and trees through pollinator movement. There is also a lack of information on pollination deficits throughout orchards and whether by increasing the intensity of cross-pollination, final nut yield is limited by within-tree resource allocation. Using caged and bagged racemes on three cultivars, we found strong evidence for self-pollination, but no evidence that hand moving self-pollen within racemes, between racemes, or between trees improved final nut set. In all cases, hand cross-pollinated racemes yielded significantly more nuts. Hand cross-pollinated racemes also produced significantly more developed nuts than open-pollinated racemes (all racemes were exposed to pollinators). However, by increasing the intensity of hand cross-pollination per tree, we showed that resource allocation probably overinflates these measures of pollination deficit in macadamia. Despite this, our findings point to an opportunity to increase yields through additional cross-pollination, as high-intensity hand cross-pollination of flowering racemes within trees still resulted in increased nut set. Although self-pollination can occur in macadamia, to optimize yield potential, strategies to maximize cross-pollination should be adopted.

Pollen-ovule relation in Adesmia tristis and reflections on the seed–ovule ratio by interaction with pollinators in two vertical strata

The vertical distribution of pollinators is an important component in the foraging pattern of plants strata, and it influences the reproductive system (pollen/ovule ratio) and seed/ovule ratio. Niches in two different strata from Adesmia tristis Vogel were evaluated in these aspects. This plant is an endemic shrub from the Campos de Cima da Serra in Southern Brazil. The studies were carried out from January 2010, to January 2011, at Pró-Mata/PUCRS (Catholic University of Rio Grande do Sul) (29°27′-29°35′S and 50°08′-50°15′W), São Francisco de Paula, sate of Rio Grande do Sul, Brazil. Breeding system of A. tristis is mandatory allogamy. The vertical profile in A. tristis has differentiated foraging niches among the most common pollinators. Bees of Megachile genus forage in the upper stratum, and representative bees of the Andrenidae family explore the lower stratum. The upper stratum of the vertical profile had more contribution to seed production. Adesmia tristis showed evidence of pollination deficit.

Effect of pollination on rapeseed (Brassica campestris L. var. Toria) production in Chitwan, Nepal

Rapeseed is an important cash crop of Nepal and an experiment was conducted to study the effect of pollination on its production in Chitwan during 2012-2013. The experiment was designed in Randomized Complete Block with four replications and five pollination treatments. The rapeseed plots were caged with mosquito nets at 10% flowering except natural pollination. Two-framed colonies of Apis mellifera L. and Apis cerana F. were introduced separately for pollination, and control plot caged without pollinators. Seed set increased by 48.72% with Apis cerana F. and 45.73% with Apis mellifera L. pollination as compared to the control. The highest seed yield was obtained from Apis cerana F. (1.11 mt/ha), followed by Apis mellifera L. (0.88 mt/ha), hand (0.75 mt/ha), natural pollination (0.66 mt/ha) and control (0.13 mt/ha), respectively. This study clearly indicated pollination deficit under natural condition, and therefore, management of honeybee is necessary for higher production and productivity of rapeseed under Chitwan condition.