1Department of Earth and Environment, Agroecology Program, Institute of Environment, International Center for Tropical Botany, Florida International University, 11200 SW 8th St, Miami, FL 33199, USA; ude.uif@namielkbFind articles by
2Department of Biology, Plant Ecology Lab, Institute of Environment, International Center for Tropical Botany, Florida International University, 11200 SW 8th St, Miami, FL 33199, USAFind articles by
3Department of Earth and Environment, Agroecology Program, Institute of Environment, Florida International University, 11200 SW 8th St, Miami, FL 33199, USA; ude.uif@nahcayajFind articles by
There is an urgent pollinator decline crisis across the globe, with fewer pollinators and yet increasing agricultural reliance on them to produce food and fiber crops for growing populations. Habitat loss and chemical eradication of unwanted plants has limited the floral resources for pollinators, and in farms with only one crop, there are limited resources solely during the flowering season. Weeds, or unwanted vegetation, are often the only remaining floral resource for pollinators, yet they are compulsively removed using chemicals. This article examines how weedy floral resources affect pollinators in a mango farm, Mangifera indica, a pollinator-dependent crop in South Florida, and how fruit yield is affected by either leaving weeds or removing them.
Agriculture is dependent on insect pollination, yet in areas of intensive production agriculture, there is often a decline in plant and insect diversity. As native habitats and plants are replaced, often only the weeds or unwanted vegetation persist. This study compared insect diversity on mango, Mangifera indica, a tropical fruit tree dependent on insect pollination, when weeds were present in cultivation versus when they were removed mechanically. The pollinating insects on both weeds and mango trees were examined as well as fruit set and yield in both the weed-free and weedy treatment in South Florida. There were significantly more pollinators and key pollinator families on the weedy mango trees, as well as significantly greater fruit yield in the weedy treatment compared to the weed-free treatment. Utilizing weeds, especially native species, as insectary plants can help ensure sufficient pollination of mango and increase biodiversity across crop monocropping systems.
Cultivated crops are often subject to insect–plant interactions for high yield. There has been a growing interest in environmentally and ecologically sound agriculture using beneficial insects rather than pesticides to produce food and fiber without harmful chemicals in produce and the environment [1,2]. Ecological intensification is the use of biological regulation to manage agroecosystems at various scales [3]. Natural ecosystems can inspire cropping system designs [4], and these approaches may have greatest impact in high-input farming systems [5,6]. Ecological replacement, substituting biodiversity for synthetic inputs, can enhance ecosystem services with similar crop output [6]. The presence of non-crop plants in planted floral strips may be useful in this approach, as a recent meta-analysis has shown [7]. Weeds may also provide resources that attract and maintain populations of beneficial insects, such as pollinators. Weeds—wild plants growing where they are not wanted—are seen as detrimental to crop production in agriculture by pulling resources away from the crop. This lack of weeds diminishes beneficial insects through the loss of floral and prey resources [8]. The benefits of using insectary plants in farms is well known [9,10]; however, using weeds as such in tropical fruit production dependent on pollination is relatively unexplored. Previous work has shown increased success of beneficial insects in the presence of weeds, as these insects use nectar or pollen during their adult life stage to increase life span and fecundity [11]. Pollinator populations may be bolstered in the presence of weeds, and some have been shown to be dependent on them [12,13]. This study examined how leaving, rather than removing, weeds in a mango farm affected pollinators and fruit set of this popular tropical fruit cultivated in southern Florida.
Pollinators are especially important in crops that require pollination by insects [14,15], such as mango, which is known to benefit from the presence of a diversity of weeds. Many tropical crops may be most susceptible to pollination failure from habitat loss [16,17]. Almost 35% of crops depend on pollinators globally, with pollination of at least 63 crops vulnerable to negative effects of agricultural intensification, which may reduce the diversity and abundance of pollinators [18]. The global annual economic value of insect pollination is upward of USD $173 billion worldwide [19]. Pollination by bees and other animals increases the size, quality, and stability of yields for 70% of leading economically important crops around the world [16], including mango [20]. Because native species pollinate many of these crops effectively, conserving habitats for wild pollinators within agricultural landscapes can help promote pollination services for most of the world’s crops [21].
There is a pollinator crisis in areas of intensive human land use and landscape simplification, including farmlands [22]. Insects have shown marked population declines over the past 30 years, with the average decline of terrestrial insect abundance at about 9% per decade [23]. Decline in pollinators is intertwined with habitat simplification through the expansion of monoculture practices [24] and increased applications of pesticides and fertilizers [25,26]. Pollinator abundance increases with flower abundance, vegetation height, and floral diversity [27]. The conservation of plant diversity safeguards native pollinator diversity as well as overall biodiversity and ecosystem services [28]. Mass flowering plants can act as “pollinator hogs”, which can reduce the pollination success of adjacent co-flowering neighbors by drawing pollinators from these plants [29,30]. However, mass-flowering plants can also act as magnets, producing pollination “spillover effects” through increased pollinator movements to adjacent co-flowering taxa, potentially either increasing pollination [31] or impacting it through the transfer of mixed-species pollen [32]. The presence of flower diversity before and during crop flowering facilitates pollination of the hyperabundant crop flower resource [20,33]. For a pollinator-dependent crop, creation of flowering areas can be profitable, improving production within existing areas and reducing the need for agricultural expansion, contributing to the conservation of biodiversity within a region, and increasing the habitat and resources for insects within farms [34].
Weeds have the potential to increase biodiversity of native pollinators by providing alternative floral resources for beneficial insects and encouraging them to remain in an area between crop flowering events [14,35,36]. Pollinators can use weeds as alternative resources before, during, and after the bloom of a crop, and increase crop yields if given these resources [37]. Weeds are an essential pollen and nectar resource for insects because of their continuous flowering phenology and their high species richness, which contributes directly to the pollen diversity dietary needs of insects [28]. Pollinators are healthiest, with at least 15 flowering species providing a season-long food supply [38], and weeds can provide this floral diversity. Arable weeds have specific functional traits that make them tolerant to farmlands, such as soil disturbances and fertilization, making a large overlap in the weedy potential of non-weed species.
Effective insect pollination is essential for good fruit set and yield in mango (Mangifera indica L., Anacardiaceae) [39]. Mango flowers are unspecialized, enabling pollination by most insects that are critical for fruit yield [40]. Nectar production for the attraction of insects indicates entomophilous pollination, and mango does not show adaptations for wind pollination [41]. Managed pollinators are unsuitable [42] or insufficient when acting alone [20,43,44]; honeybees are generally not attracted to mango flowers [45,46], and hand pollination is not economically viable [47]. Pollination is highly dependent on a diverse assemblage of flying visitors, which is strongly negatively affected by distance to natural habitat [46]. Small patches of native flora, planted in nonproductive margins of large mango orchards, enhance the abundance and diversity of mango flower visitors in South Africa, ameliorating the negative effects of isolation from natural habitat and pesticide use [34]. These increases were associated with significantly higher mango production, including the Keitt variety. Two co-flowering species can compete with or facilitate each other for flower visitors, although some studies suggest that facilitation is more likely between plants with unequal flower abundance [29] or that attractive species may facilitate less attractive species, as is the case with mango [20,33].
The insect orders Diptera, Hymenoptera, Lepidoptera, and Coleoptera are the most common insect visitors to mango flowers and carry mango pollen [39,41]. Most pollinators of mango belong to order Hymenoptera, but Diptera (flies) have been suggested as the dominant pollinators in Israel [39]. Dipteran species are good pollinators of more than 550 species of flowering plants, and the family Calliphoridae (blowflies) are the suspected main pollinators of mango in India [48]. Additionally, Chrysomya, Lucilia, and Musca sp. (Diptera) were reported as mango pollinators because of their visiting frequency and abundance [48]. Flower flies (Syrphidae) are also good pollinators of mango [49], as they transport pollen for long distances and reproduce rapidly [50]. The introduction of three pollinators—the honeybee, the bumblebee (Bombus terrestris), and the housefly—resulted in much higher yield of mango vs. caged pollinator-free trees [39]. Common blow flies may also serve as effective mango pollinators and are less likely than honeybees to abandon the mango orchard for more attractive blooms, in Israel as well as in the United States [39].
The aim of this study was to examine if weeds can increase biodiversity of pollinators and ultimately benefit Mango (Mangifera indica) crop cultivation. We asked the following questions:
If weeds benefit mango trees, we anticipate a higher abundance and diversity of pollinating insects on the mango trees where weeds have been left to grow (weedy treatment) in comparison to mango trees that have been cleared of all weeds (weed-free treatment). Perhaps this enhanced pollinator abundance will increase fruit production.
As an artillery plant enthusiast, I’m always looking for ways to maximize the yield of these fascinating indoor plants. Proper pollination is crucial for ensuring healthy growth and optimal seed production. In this comprehensive guide, I’ll walk you through the key steps for successfully pollinating your artillery plants and boosting your yields.
Artillery plants scientifically known as Pilea microphylla are unique tropical houseplants prized for their oval-shaped leaves and their remarkable ability to “shoot” out pollen when the leaves are touched. They are primarily self-pollinating plants, meaning they can self-fertilize without the need for external pollinators.
However, manually assisting with pollen transfer between flowers can further improve seed set and increase yields. Pollinating your artillery plants allows for cross-pollination between different plants, leading to greater genetic diversity and more robust plants. It also directly impacts the number of seeds and fruits produced.
Below I’ll outline the key steps involved in effectively pollinating your artillery plants and maximizing your harvest
When to Start Pollinating Artillery Plants
Identifying the optimal time to pollinate is crucial Artillery plants will start flowering when they reach maturity, usually 8-12 months after propagation The small, white flowers will emerge from the leaf axils, signaling the plant is ready for pollination.
Monitor your plants closely to catch the flowers as soon as they appear. Pollinating early in the flowering stage will give the plants more time to develop fertile seeds.
Step 1 – Prepare the Pollen
Start by gently shaking or tapping the flower clusters to release the pollen. Use a small brush, cotton swab, or your finger to collect the pollen grains. Transfer the pollen to a piece of paper or plastic wrap to avoid contaminating the brushes.
Examine the pollen closely to ensure it is viable – fresh, yellow pollen grains are ideal. Discard any pollen that appears dry, crunchy or discolored.
Step 2 – Transfer the Pollen to the Stigma
Using your pollen applicator, gently brush the viable pollen grains onto the stigma of the artillery plant flowers. The stigma is the sticky, raised structure located at the tip of the flower’s pistil.
Be sure to evenly distribute pollen across all available flowers. Adequate pollen transfer is key for successful fertilization.
Step 3 – Repeat Daily
Pollinating your artillery plants is not a one-time event. For maximum seed production, you’ll need to manually transfer pollen daily throughout the entirety of the flowering period.
Repeat the pollen collection and application process for all open flowers each day. Consistency is vital for fruit and seed development.
Step 4 – Allow Time for Fertilization
Once pollinated, give your artillery plant flowers sufficient time for the pollen to germinate and fertilize the ovules.
Properly fertilized flowers will begin forming seeds pods after approximately 4-6 weeks. Monitor seed growth and collect seeds once pods turn brown and dry.
5 Tips for Maximizing Pollination Success
Follow these key tips to ensure effective pollination and increased yields from your artillery plants:
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Maintain ideal growing conditions – Proper lighting, temperature, water and nutrients promote flowering.
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Encourage natural pollinators – Introducing beneficial insects can supplement hand-pollination.
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Avoid over-handling flowers – Gently collect and distribute pollen to prevent damage.
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Use freshly collected pollen – Old, dry pollen has lower viability for fertilization.
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Practice good hygiene – Clean tools between plants to prevent pollen contamination.
What Results to Expect After Pollination
With consistent, effective hand-pollination, you can expect:
- Increased number of seeds and seed pods
- Larger, more abundant fruit production
- Improved plant vigor and vitality
- Greater genetic diversity among offspring
- Higher propagation success rate
- An ongoing supply of new artillery plants
In essence, diligent pollination efforts directly translate to higher yields from your prized artillery plants.
Troubleshooting Pollination Issues
Sometimes, even with regular pollination, seed yields may still be lower than expected. Here are some potential issues and solutions:
Problem: Few or no seeds forming after pollination
Solution: Pollen may be sterile or non-viable. Collect fresh pollen and re-apply.
Problem: Seeds not reaching full maturity
Solution: Growing conditions may need improvement. Assess light, watering, etc.
Problem: Seed pods shriveling before maturity
Solution: Pollination was unsuccessful. Check pollen viability and technique.
Concluding Thoughts on Artillery Plant Pollination
Pollinating your artillery plants by hand is extremely rewarding and can significantly boost your propagations success and overall yields. Pay close attention to plant signals, use viable pollen, and maintain diligence in repeating the process daily. With the right approach, you can master the intricacies of pollination and unlock the full potential of your artillery plant collection.
Materials and Methods
The field experiment was installed at a conventional mango farm (20 acres), variety “Keitt”, within the major agricultural area of Homestead, Florida (25°29′42.9″ N 80°29′30″ W). Trees were evenly spaced in 20 × 20 feet intervals. Distance between rows was approximately 20 feet. Two treatments were applied to the trees: weedy vs. weed-free. Three sections of 10 trees were assigned per treatment, with buffer rows and trees surrounding the treatments ( ). For the weedy treatment, unadulterated weed growth was allowed between the trees, and weed species identified. All were in the same area of the site as per maintenance requirements of the farmer. For the weed-free treatment, weeds were removed around the crop, using a mower and string trimmer, a tool for cutting grasses, small weeds, and vegetation. All weed specimens within the weedy treatment were vouchered and identified.
The mango cultivation area of this farm is made up of 24 rows with 47 mature mango trees each and a mix of Tommy, Keitt, Kent, and Florida Red varieties. The weed treatment was placed in row 24 ( ), with buffer trees separating the sections, due to restrictions in field maintenance of separating the treatment across multiple rows. The 3 weed-free sections were assigned to 10 trees each in rows 2, 4, and 6.
The management practices used at the study site are ecologically oriented and minimal for a large conventional farm compared to other mango farmers in the area, and no insecticides are used by the grower to allow balanced insect biological control of pests. Similarly, mango farmers in the United States are limited in what chemicals they can apply to trees compared to those in other countries; for example, the use of Topsin to treat mango malformation is outlawed in the US [51]. The major chemicals applied to the trees by the grower were fungicides to kill anthracnose, bacterial, and fungal pathogens. Before fruiting, micronutrients were added to all the trees as well as cow manure instead of synthetic fertilizers. Mowing occurred in the farm as needed (outside of the weedy treatment) with a sickle bar mower beneath the trees, rather than herbicidal eradication of weeds.
3. Field Data Collection
Observations and collections of insects were made from the mango trees in both treatments. Insects interacting with the crop M. indica were recorded and collected weekly for six months including the major 8-week blooming period of mango. Five-minute watches were made recording insect interactions, observing, and collecting specimens on each of the 30 mango trees in both treatments totaling 7500 min of observations across the 25 weeks. Timed focal point observations were conducted weekly before, during, and after the peak mango flowering season (from November until May), similar to methods outlined in Carvalheiro et al. 2012 [34].
The timing of observations per treatment per day was changed for each data collection day by alternating the order each tree was visited, to have a breadth of observations across the day. Close focusing binoculars were used to observe specimens in the upper canopy of the mango trees if needed. In each watch period per tree, all insects and flower visitors were recorded and collected for identification. Each insect specimen was collected if novel or if sight identification was not possible. Additionally, specimens were collected if they displayed notable behavior such as pollinating flowers using an insect aspirator, collection bag, or net. Specimens collected from the field were immediately placed into a plastic bag that were kept cool and stored in a freezer (0 °C) until further identification. Voucher specimens were pinned or stored in ethanol in vials and are maintained in the authors’ collection; they will eventually be deposited in the Florida State Collection of Arthropods. There were two flushes of inflorescences on the mango trees during this season, allowing insects to be collected from mango flowers from 12/05/2019–05/08/2020.
Statistical analyses were performed with SPSS software. Descriptive information is presented to describe the variables of interest overall and by treatment. These include means, standard deviations, frequencies, and proportions. To compare means between treatments, a two-sample t test was used, and to compare proportion, chi-square test was used to see if the observed distribution of insects differed from the expected distribution. Statistical analyses of effect of treatment on insects compared between the weedy and no-weed treatment, as well as these effects on fruit yield, was performed using a general linear model by applying multivariate analysis of variance (MANOVA) with insect/fruit yield measures as the dependent variable (multiple Y’s) as a function of treatment while adjusting for tree age. Multivariate tests such as Pillai’s Trace, Wilk’s Lamba, Hotelling’s Trace, and Roy’s Largest Root examined overall model significance, followed by further analyses using simplified F-test comparison adjusting for multiplicity. All differences or associations were considered significant at the alpha level of 0.05 after the adjustment for multiplicity where appropriate.
Fruit counts per tree were performed visually when nearly mature fruit were set on the tree as well as counted when harvested by the grower. Visual fruit yield counts were performed after bloom and all fruit had been pollinated and set (number of unripe fruits per tree, circa 6 weeks after the end of flowering ceased, as in Carvalheiro et al., 2012 [34]. For each visual count, two different observers’ counts were averaged. A marker for the starting point of observation was placed on the ground, and an observer used a hand clicker counter and moved around the tree counting each individual mango fruit. Early fruit set is only an indication of pollination efficiency but may not be a good indicator of pollination quality and, hence, of final crop production and economic value [34]. Therefore, we also obtained information on final production as pounds of commercially suitable mangoes directly from the farmer. Fruit was harvested green for the Asian market early in the season in May and July. Harvest of mango is performed manually by pickers; therefore, a count was to be taken as each tree was picked.
This was part of a larger study in which all insects associated with mango and weeds were collected. There were 3786 total records of flower visitors observed and/or collected during this study.
How to increase yield with Hand Pollination
FAQ
How does pollination increase crop yield?
How can we boost pollination?
What are two strategies of plants to increase the chance of pollination?
Why does cross-pollination increase yield?
Is hand pollination a good idea?
Here are some signs that hand pollination is a good idea for your plants. You never see bees or other insects hovering around your plants. You’re growing plants indoors, in a screened porch, or inside of a greenhouse. The fruit on your plants shrivel and die before maturing.
How do you hand pollinate a flower?
Self-pollinating plants are the easiest to hand pollinate. Typically, you’re just making sure the pollen gets down into the middle part of the flower. All you need to do is gently use your brush and place it inside of each flower on the plant. Doing so moves the pollen down into the pistil, which is the middle part of the flower.
Why do gardeners use manual pollination?
Many gardeners use manual pollination to increase the likelihood of pollinating their plants, especially if they worry that bees might be lacking in their area. Zucchini plants, for instance, usually send out male flowers before the female flowers emerge. No big deal if the males are out and fruit hasn’t formed, yet.
Why is hand pollination necessary for zucchini plants?
Hand pollination is necessary for zucchini plants because they have separate male and female flowers. The pollen from the male flower must be transferred to the female flower for successful fruit development. How often should I hand-pollinate my zucchini plants?