Vines crops for example as pumpkin, squash, cucumber and watermelon are some of New York State’s most valuable vegetable crops. These crops require pollination by bees, the most well known of which is the honey bee, Apis mellifera.
Honey bee hives are placed in vine crops during the time they need to be pollinated. Unfortunately, Colony Collapse Disorder (CCD), parasitic mites, viruses, and other pathogens continue to cause significant losses in populations of honey bees throughout the US.
Fewer honey bee hives are now available for vine crop growers and the cost of renting hives has increased from approximately $30 per hive too!$75 per hive.
With no relief in sight, growers will continue to pay more for renting hives, unless alternative pollinators are identified to service their vine crops.
As the number of visits of bees increases on plants their seed & flower production also increases. Similar is the case with the pumpkin as more honey bees visit pumpkin more pollination process occurs which results in more yield of that crop.
Apis mellifera L. accounted for 73.4% of the visits made by bees, collecting pollen during 34.5 s per flower and nectar in 43.9 s and 29.3 s from female and male flowers, respectively.
Importance of pumpkin (Cucurbita maxima )
Few reports are given on the pollination of commercial crops and pumpkin is one of them. It was originated in Central America and have great economic importance for them as they use it as human food and also for animals as feed.
Honey bee and Pumpkin Relationship
Honey bees visit pumpkin for their nectar and as a result, helps in the pollination. According to research, like the visits of A. mellifera to the female part of pumpkin plants, up to 16 visits, the increase in seed numbers, fruit set and also in the growth of fruits.
Only A. mellifera helps in the pollination while others only harvest nectar from the flowers and do not carries pollen. The shown graph has the data of two years of observation of bees visiting pumpkin. A. mellifera, T. spinipes and D. speciosa were the insects most frequently found on pumpkin flowers in both years.
A greater number of visits occurred early in the day with higher temperatures, but on colder days the visitation period lasted longer. Understanding the importance of honey bee A. mellifera, it is the only pollinating agent visiting at 9 A.M
The most vital pollinating insect observed on flowers of pumpkin was A. mellifera, which collects nectar & pollen. T. spinipes only collect nectar and D. speciosa suckes sap from the petals of the flowers. These both do not pollinate pumpkin flowers.
A. mellifera is an effective pollinating agent of the pumpkin crop. Fruit production occurs only when the insects visit the flowers up to 9 h. Fruit set, fruit size and weight and number of seed increased as the number of visits by A. mellifera also increased up to 16 visits per female flower, at which the highest fruit set level was reached.
So, honey bee especially A. mellifera plays a key role in the production of the best quality pumpkin crop because it is directly involved in the pollination of that crop. Honey bees pollination increases fruit size of all but decreases the individuals’ fruit size i.e., <5kg
All cucurbits require multiple flower visitation with pollen transferred to all parts of the large stigma to yield perfect, well-ripened and properly shaped results with the characteristics highly important for the marketability of these commodities. Supplemental rental of honey bee colonies as ‘crop insurance’ still is the best alternative.
In short, the pumpkin is pollinated naturally but can also be pollinated artificially by renting honey bees. This increases the yield of a crop. The flowers of the cucurbit family open in morning times only and the A. mellifera is the only bee visits at this time.
Pollinating through honey bee produces the homogeneous crop which is of great economic importance. The most important factor in this process is the number of visits on the flowers by the honey bee. The number of visits is directly proportional to the yield and seed rate of crop.
So, the country where pumpkin is staple food or has great economic importance, honey bee pollination is very vital there.
Effects of Honey Bee pollination on pumpkin fruit and seed yield
Cucurbits vegetables require insects, such as honey bee to transfer pollen from staminate to pistillate flowers(Delaplane and Mayer, 2000; Robinson and Decker-walters,1997). Honey bees and squash bees are the most important insect pollinator of pumpkin.
Jaycox et al. (1975) indicated that as the number of bees visits to pistillate processing pumpkin flowers increased from 1 to 2 fruits set is increased up to 58% and the numbers of seeds per fruit increased up to 75%. In watermelon, Brewer(1974) found a high correlation between both seed numbers and seed weight.
These results indicated that a large honey bee population ensures maximum flower visitation, pollen depositions, and tends to increase yields of cucurbit crops.
When honey bee colony presence is compared to honey bees colonies’ absence on jack-o-lantern pumpkin yields. The pollinator activities are the same for both experiments with about 2 to 3 and 5 to 7 pollinator visits to the pistillate pumpkin flowers per hour for these treatments without or with honey bees colonies, respectively.
Over the primary pollination period, a total of about 10 to 15 and 25 to 35 pollinator visits to pistillate pumpkin flowers are recorded for these treatments without and, with honey bees colonies.
Although bumblebees, carpenter bees, honey bees, and the squash bees were pollinating the pumpkin the honey bees provide the most visits in the pumpkin. honey bees provide different influence on the pumpkin cultivars but the yield production of pumpkin fruit crop increases with the increase of honey bees colonies
Is it worth supplementing pumpkin fields with bees?
Yes, the yield per acre of the pumpkin increases as we increase the total numbers of colonies in the field. Bombus impatiens is the most efficient pollinator of pumpkin compared with other common species, including the honey bee and squash bee, Peponapis pruinosa.
Not only are bumblebees efficient pollinators, but they are also naturally abundant and available for commercially, making it a perfect candidate as an alternative pollinator to honey bees in a pumpkin field.
Yet, supplementing pumpkin fields with bumblebees colonies will not necessarily increase pumpkin yield. These seemingly contrasting results may be explained by differences in the local abundance of native common eastern bumble bees population n near pumpkin fields.
For example, a pumpkin field near a locally abundant bumblebee population would not need to be supplemented because the native population would provide sufficient pollination of the crop.
Conversely, a pumpkin field that is near a low population of bumblebees may benefit from supplementing with commercial bumblebees to increase pollination and therefore fruit yield.
Authors: 1Zohaib Afzal,2Faheem Shoukat
1Department of Soil Science, 2Department of Entomology,
MNS- University of Agriculture, Multan, Punjab, Pakistan.