Tips: This article involves the actual map of insects, careful observation may find its cuteness, but really scared readers should be cautious Oh ~ ~
Many friends who plant flowers, especially those who plant flowers in the moon, have experienced this situation: when they wake up, the carefully cared for plants are not known to be patronized by some creatures, and the strange gaps in the leaves are unbearable to look at, but the murderer is missing. Just when he was confused and angry, a furry bee flew in front of his eyes. Don't think that it is only visiting the flowers to collect nectar, it is the one who causes the evil of the leaves.
Crime scene Image source: agrilife.org
The one that cuts the leaves and creates a half-moon or full moon-shaped gap are the Megachilidae insects, and the megachile nipponica that prefers to patronize the moon flowers in urban ecosystems is the Megachile nipponica. What is the purpose of the leaf-cutting bee's special behavior of "mutilating plants"? Is it a beneficial insect or a pest? What should I do when I encounter it?
The killer Image source: go.gov.sg/
Brother of the Bee
Leaf-cutting bees are similar in appearance to bees bees because they are originally brothers of a family, both of which belong to the general family of bees, but leaf-cutting bees have very different habits. Common bees (such as the Oriental Bee Apis cerana) are social bees that live in groups; Leaf-cutting bees, on the other hand, prefer to be alone and belong to solitary bees.
As the name suggests, the biggest feature of this type of bee is that it can cut leaves. Looking at the entire insect class and even the animal kingdom, there are only two types of creatures with such special habits, in addition to leaf-cutting bees, the other is leaf-cutting ants (to review the latter, please click: This is the ant farm, where I farm!). ）。 Both types of insects use well-developed mouthparts to cut plant leaves and bring them back to their nests. The difference is that leafcutter ants do this to grow food, while leafcutters are doing this to build houses, specifically, to build "nursery rooms" for offspring.
Busy leaf cutter bee: "All for the child" Image source: pinterest.com
Master Builder: Site Selection - Cleaning - Building Houses
Leafcuttering bees' special nesting behavior is only seen in female individuals, which means that these people who are busy flying around cutting leaves are expectant mothers who are about to lay eggs. In fact, cutting leaves is not the first step in nesting, before the female leafcutter bee will first determine a suitable place. Small environments with natural openings such as tree holes, dead branches, reed poles, empty snail shells and even bricks are the nesting points that female leaf-cutting bees like.
Image source: nhsn.org.uk
Image source: beebettercertified.org
After determining a suitable nesting site, the female leafcutter bee will first clean up the garbage such as small mud blocks or dead leaf fragments in the natural small hole. Once the nesting site has been cleaned, the female leafcutter bees take the busiest step: finding and cutting a large number of plant leaves nearby. At this point, the female leafcutter bee turns on the efficient mode, and the leaf cutting speed is very fast, because it prepares a separate nest chamber for each egg in the abdomen, and each nest chamber needs to be rolled with nearly many leaves.
For example, the double-spotted leafcutter bee (M. leachella) will cut the leaves within 2 meters of the nesting point, cut one piece as soon as every 5 seconds, and then use up to 14 leaves to form a nest chamber. What's more, the white-spotted leafcutter bee (M. strupigera) to build a nest chamber with a blade dosage of up to 33 pieces.
Guess how many studios there are in this row of apartments Image source: extension.msstate.edu
Under the X-ray, the separation of the nest room is obvious, and this time it can be counted clearly Image source: Reference 7
After the "single room" is ready, the female leafcutter bee will prepare food inside for the offspring, also known as "bee food", which is often a mixture of pollen and nectar. Once the food is prepared, the female leafcutter bee carefully lays an egg on the bee food and seals the individual nest chambers with leaves before continuing to make the next nest chamber. Each nest chamber is closely connected, end to end, like a townhouse.
After the eggs hatch in the nest chamber, the larvae feed on bee food and molt and grow, eventually becoming adults. During the adult stage, the leaf-cutting bee has a well-developed jaw, which can bite through the leaves and leave the nest to find the next generation of the same kind.
Baby leaf-cutting bees in a single room, mating their own food Image source: mindenpictures.com
There are always exceptions to everything, and not all leaf-cutting bee insects have this special nesting habit, but there are also "lazy" guys who don't nest on their own, such as the coelioxys spp. that steals and parasitism. The sharp-bellied bee itself does not cut leaves or build a nest, but always circles around other types of leaf-cutting bees, the purpose is to "steal the house". After selecting the wronged head, the pointed bee will lay its own eggs in the nest built by the other party, and the sharp-bellied bee eggs will kill the original leaf-cutting bee babies after hatching. This kind of behavior is completely the cuckoo bird of the insect world!
C. C. (C. A. Kelly) waiting for an opportunity at the door of someone else's house. aurolimbata) Image source: eunis.eea.europa.eu
Cutting leaves and cutting flowers, is it not a pest?
In addition to the leaves, the flowers can also be used as material for female leaf-cutting bees to build their nests. Researchers investigated the material composition of 92 leaf-cutting hive chambers and found that 54% of them used marigold petals. There have been numerous cases where leafcuttering bees use both leaves and petals to build their nests, and that this practice does not affect the growth and development of leafcuttering bee offspring. Call it a leaf nest flower nest, living comfortably is a good nest.
The question is, is the leaf-cutting bee, which cuts both leaves and flowers, considered a pest that harms plants?
A nest of a mixture of petals and leaves Image source: Reference 6
In fact, leafcutter bees cause limited damage to plants and do not cause plant wilting and death, so leafcutter bees are not "pests" in the traditional sense. In contrast, leafcutters are also important pollinators for many plants, such as alfalfa grass, blueberries and other important crops. Some specific species of leaf-cutting bees have strong pollination specificity and high pollination efficiency, so they have become the object of introduction by countries to promote their own agricultural and animal husbandry production. Rotundata) is like this.
Native to Europe and West Asia, Alfalfa leaf-cutting bees have a highly synergistic pollination relationship with Alfalfa, which can open the special keel petal structure in its petals to achieve efficient pollination of alfalfa, and is a powerful helper in the alfalfa cultivation industry. The United States first introduced alfalfa leaf-cutting bees from Europe in the mid-1930s to improve the seeding rate of local alfalfa and was successful. In the 1960s, Canada introduced the bee and developed a stable and mature breeding and application system.
Release of captive-farmed alfalfa leaf-cutting bees Image source: ars.usda.gov
The continent is also a large livestock country, with large areas of alfalfa fields, but the low yield of Medicago sativa seeds on the mainland is partly due to the lack of efficient pollinators. As early as 1988, the mainland began to introduce alfalfa leaf-cutting bees and conduct field experiments in Beijing, Gansu and Jilin. The field experiment data is gratifying, showing that the seeding rate of alfalfa has increased significantly, with an increase of 51.6% to 107.0%, which is 3-5 times the pollination effect of other bees.
Don't warp, know that you are very good at pollination Image source: wikipedia.org
Pollination more efficient than bees? That's a good name for leaf cutter bees! Leaf cutters are able to pollinate efficiently, and the hair on its stomach and body is not small. Common bees collect pollen on specific structures of the hind feet, while leafcutters pollinate through a large number of brush-like hairs on the ventral surface of the abdomen, while the denser and more developed fine hairs on the whole body are also stained with more pollen.
Look for it, one with pollen on the leg and one with the belly Image source: utsc.utoronto.ca
What should I do if I find a leafcutter bee?
In this way, the leaf cutting bee is more powerful than excessive, and even the work is far greater than the excessive. The next time the small garden at home is patronized by leaf-cutting bees, don't kill it, after all, it cuts a few leaves and a few flowers, it will not kill the plant. And the leaf-cutting bee has a gentle temperament, as long as we don't hurt it, it will not actively sting. The way to deal with it is not to deal with it.
Not driving away and not killing leaf-cutting bees is a "basic operation". The advanced "advanced operation" is to give them more room to live and retain these beneficial insects.
There are about 4,000 species of leaf-cutting bees worldwide, accounting for about 20% of pollinator bees, but these bees, like other organisms, are suffering from declining diversity, and the lack of living space caused by rapid urbanization is one of the reasons for this phenomenon. The hot "insect lodge" in horticulture and nature education in recent years may be one of the effective ways to increase the diversity of leaf-cutting bees in cities.
Image source: Shanghai Chenshan Botanical Garden public number
The practice of insect hotels is to place materials such as dead branches and leaves and wooden stakes to provide shelter for all kinds of insects to attract them. Recently, the insect hotel built by Shanghai Chenshan Botanical Garden has welcomed the special "guest" of leaf-cutting bees. Leaf-cutting bees have a small shelter in the developed city of Shanghai; It will use its powerful pollinatory ability to repay the city, allowing more garden plants and wildflowers to bloom in a city full of reinforced concrete.
Hopefully, leafcutters with special nesting habits and efficient pollination will be more common in the future, because that means that the spring colors in the coming year will be more colorful.
Nanchang City leaf-cutting bee visiting flower species survey Image source: Reference 2
Author: Ge Yingqiang
Resources:
He Bo, Huang Dunyuan, Su Tianjuan, et al. Observation of biological characteristics of leafcutter wasps[J]. Acta Environmental Entomology, 2016, 38(6):1237-1237.
Jin Xiaofang, Hao Fuliu, Xu Zijun, et al. Preliminary discussion on the conservation of bee diversity in urban solitary bee[J]. Modern Horticulture, 2019(18):3.
Meng Yanhua, Xu Huanli. Nesting habits of bilobited leafcutter wasps[J]. Acta Entomology, 2008(11):1170-1176.
Tai Fahong, Zhang Yongdong. Research and application status of Alfalfa leafcutter wasps in alfalfa seed production[J]. Journal of Animal Husbandry and Veterinary Medicine, 2022(041-001).
ZHU Mengmeng, LI Dongning, ZHANG Rong, et al. Preliminary study on nesting law of alfalfa leaf cutting bees[J]. Ningxia Agriculture and Forestry Science and Technology, 2017,
58(12):3.
[6] Cecala J , Rankin E W. Petals and leaves: quantifying the use of nest building materials by the world's most valuable solitary bee. [J]. Literature Cited, 2021:e03584.
[7] Pitts-Singer T L, Cane J H. The alfalfa leafcutting bee, Megachile rotundata: the world's most intensively managed solitary bee. [J]. Annual Review of Entomology, 2011, 56(1):221.
[8] Rozen J G, Vinson S B, Coville R, et al. Biology and Morphology of the Immature Stages of the Cleptoparasitic Bee Coelioxys chichimeca (Hymenoptera: Apoidea: Megachilidae)[J]. American Museum Novitates, 2016, 70(3679):1-26.
[9] en.wikipedia.org/wiki/Megachilidae
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