CC BY
78
UDC 633.12
BUCKWHEAT IN THE CONSERVATION OF INSECTS SPECIES DIVERSITY
Naumkin V.P., Lysenko N.N., Doctors of Agricultural Sciences Orel State Agrarian University, Orel City, Russia E-mail: lysenko [email protected]
ABSTRACT
Buckwheat - one of the most important of the field rotation crop, attracting and keeping a large number of insects. Entomocenosis of a buckwheat field consists of more than 170 species of insects pollinators, phytophags, entomophags. The dominant species are pollinators; there are about 90 species of them. They feed on nectar, pick up it and make pollination possible. Bee honey, wild bees, bumblebees, wasps, other hymenopterans, dipterous, beetles are widely spread. All of them are polytrophs - they visit many species of flowering plants, including buckwheat. Insects-phytophagous is the second largest group; about 50 species feed on seeds, roots, shoots and vegetating plants until the crop harvesting. The third group of insects, whose imagos feed on flowers and larvae (and sometimes imago) hymnical or parasitize on phytophags of buckwheat and on other crop rotation fields or on neighboring natural biotic communities: Coccinellidae, Chrisopidae, Syrphidae, Tachinidae, Phasiae, parasitic hymeonopterans. These insects need not only buckwheat plants, but also its phytophags that are food for their larvae. Entomophags is a group which includes about 30 species. The fifth group of insects is real predators - includes Carabidae and Staphylinidae mainly. The sixth group is insects, occasional visitors of buckwheat agrobiocenosis. Relations between insects, living in the buckwheat field, with other biocenosis components, are generally trophic (direct and indirect): «plants - insects phytophags»; «plants - insects phytophags - entomophags», «insects «neutrals» -entomophags»; and phoryc (zoochory): plants - insects pollinators. Topical communications appear under the influence of the plant defining living conditions of phytophags and entomophags (buckwheat crops as a habitat of insects with granting possibility of a shelter, a meeting of genders, reproduction and habitation of different stages of evolution).
KEY WORDS
Buckwheat sowing; Entomocenosis; Agrocenosis; Insects pollinators; Phytophags; Entomophags; Trophyc relations; Phoryc relations.
Buckwheat agrocenosis differs from others field agrocenosis that, besides the biological features of crop, chemical means of protection from undesirables practically aren't used during cultivation technology. The state catalog of pesticides and agrochemicals allowed for use in the territory of the Russian Federation in 2013 and approved by the Ministry of Agriculture of the Russian Federation, doesn't contain any insecticide, fungicide and the herbicide allowed for use on buckwheat during vegetation [1]. Only Thyram is allowed to use for seeds processing and herbicides on the base of 2,4-D dimethylamine salt (Dikopur, Dikamin-D, Aminopelik) are allowed to use in 2-3 days prior to seedlings.
The range of growth stimulators of the plants, allowed for use at vegetation of this crop is wider: in a phase of 2-3 leaves it is allowed to use a preparation Bigus - a water solution of potassium salt of humic acids, during the bud formation period - the preparation Epin-Ekstra (2,4-epibrasspolid) and Immunocitofite (ethylic ether of arakhidonovy acid), at the beginning of blossom - Novosil, Biosil, Silk (triterpenic acids), Emistim (2,4 - epibrasspolid). However, the growth regulators are rarely used in the crop production, and if they are used, their influence on the entomofauna is of no significant value. That is the technology of crop cultivation provides safety of many species of insects.
On the other hand, being entomophillous buckwheat attracts a large number of insects feeding on nectar and pollen of flowers. Phytophags present the second group according to the economic importance, and insects-entomophags present the third group [2-4].
According to the variety and abundance of insects, entomocenosis of buckwheat fields is unique in crop rotations and provides the formation of various relations between insects and crops, contributes to the reproduction and the survival of many useful species, but also presents a fodder base for phytophags. There are the following groups of insects: 1) geoby -inhabitants of the soil; 2) gerpetoby - inhabitants of the land surface layer; 3) phyloby -inhabitants of the herb layer; 4) aeroby - inhabitants of higher layer [5]. All these groups are presented in entomocenosis of buckwheat sowing.
The study of insects of buckwheat agrocenosis is important, helps to determine species diversity, number dynamics, the dominance of species and their economic value for crops and for other crops rotations.
RESEARCH METHODOLOGY
Gathering of insects was carried out on buckwheat fields of The All-Russia Research Institute of Legumes and Groat Crops (GNU VNIIZBK) since 1985. Observation of insects was also conducted on industrial buckwheat seeds in farms of the Orel region. The routing method was used. Insects that live on the surface of plants or soil were taken into account, using a square frame with a side of 50 cm, which is placed on the ground so that it overlap plants, typical for the habitat and for the spacing. For some species, incapable of visual recording, was used the method of shaking off plants in the sweep net. The standard entomological sweep net with hoop diameter - 30 cm, bag depth - 60 cm and handhold length 1 m was used for mowing. One sample composed from 10 to 20 sweeps of the net. 510 samples were taken, which compose 100 sweeps of the sweep net.
Figure 1 - Carrying out the recording of insects on buckwheat crops on the experimental field of The All-Russia Research Institute of Legumes and Groat Crops (GNU VNIIZBK) by V.P. Naumkin
During the data processing, we calculated the average number of species per 10 or 100 sweeps of the sweep net. The definition of insects was carried out on the basis of identification of insects of the correlative systematic groups.
RESULTS AND DISCUSSION
In the results of investigations, and on the basis of study of the sources of information, it was found out that there are more than 170 species of insects on the buckwheat seeds of the Central Chernozem zone. The largest group (about 100 species) is insects, visiting buckwheat flowers - mainly pollinators, pickers of pollen and nectar, and feeding on them. Flowers of buckwheat are gathered in axillary racemes, we can see 500-1500 flowers on the
well-developed plant. Flowers are rather large, white, light pink, red flowers, they are well noticeable and available for the majority of insects .The peculiarity of flowers of buckwheat is their heterostilism - when one plant has short stamen and long column of a pestle, and others - on the contrary. Such structure attracts both large and small insects. Duration of blossoming of buckwheat is significant - since July until harvesting in September. During blossoming buckwheat produces a large amount of nectar and pollen that attracts a large variety of insects. It was shown earlier that 83 species of insects from 5 groups take part in pollination of buckwheat [6]. Representatives of hymenopterans (32 species), dipterans (30) and bugs (11), are wide ranged. Class of lepidopterans and the neuropterans are presented by 7 and 3 species. Syrphide (19 species), bumblebee (15), single bee (13), Coccinellidae (6 species) are the most various among systematic group. Stratiomyidae, wasps, Chrysopidae are presented by 4 species. Other groups - Tachinidae, flies sarcophagidae, Muscidae,Cantharidae, Cassidinae, Lepidoptera and other are presented by 1-2 species.
In some years the number of registered species ranges from 30 to 50. Single bees (are presented by families:Andrenid, Galiktid, Kolletid), bumblebees, Syrphidae, Coccinellidae are liable to the considerable annual changes. The total number of insects ranges from 9 to 18 rogues per 10 net sweeps.
According to the data obtained through years was found out that the greatest percentage of pollinating insects are Hymenoptera (44,76 %), 80,84 % of them are honey bees. In buckwheat fields agrocenosis honey bees appear with the first flowers blossoming. The largest number of bees appear during the period of mass buckwheat flowering. There are small numbers of bees at the end of flowering.
Honey bee shows maximum activity on buckwheat crops from 9 a.m. to 1 a.m. with the peak in 11 a.m. (50,48% of total quantities of bees). After 1p.m bee fly is significantly decreased, and by 5 p.m. stopped. Bee flight to buckwheat is determined by weather conditions. In hot days we can meet them more often in the first half of the day, it is the first, the greatest peak activity, then in the middle of the day occurred recession, and then appeared the second, smaller on number, after-dinner peak activity. In the days with low temperature bee flights is less in number, but longer and more even. For example, in summer of 2002 bees were met on buckwheat field throughout the day. Because of dry weather and weak allocation of nectar by buckwheat flowers bees pick up pad aphids. Thus, the direct link of «plant-bee» was violated.
Studying of Hymenoptera species composition shows that they are situated in the following sequence in decreasing order of its representatives: honeybee - 36,90%, single bee
- 4,64, wasps - 2,47, bumblebee - 0,72%. Flight of insects of Hymenoptera species within the day was as follows: in the morning (9-11 h) and their number in the crops ranged 25-46 %. The maximum number was registered in 11 a.m., and from 1 to 7p.m. a sharp falling in visiting was observed.
There are 12 species of bumblebees and 3 species of cuckoo bees on the buckwheat crops. The big stone bumblebee, big earth bumblebee, small earth bumblebee were prevailing types. Field, garden and city bumblebees were seldom met on buckwheat crops, other types were single met. The maximum attendances of buckwheat by them were at 11 a.m. - 1 p.m. with sharp falling at 4 p.m. The greatest number was registered in the first half of buckwheat flowering. Apparently, they don’t find the main but additional food on buckwheat. These are large insects and before starting picking up nectar, the bumblebee has to ensure steady position on a flower. That is why bumblebees don't sit on buckwheat flowers for a long time.
Representatives of single bee were less met on buckwheat crops (from 9 a.m. to 7 p.m.
- one-two specimen on a unit of account); dynamics of their flies is similar to a honeybee fly.
Syrfidae - the most numerous species in the dipteran family .They appear early in the morning. Their greatest number was observed from 9a.m. to 5 p.m. with a maximum at 11
a.m. Other representatives of Dipterans were met on buckwheat crops throughout the day. The maximum number of species was observed at 5p.m. (19,72%).
Similarly bees, we can find bugs on buckwheat crops. The greatest number was observed at 11 a.m. Recession begins from 5 p.m. to 7 p.m. their number reaches 9,42%.
Chrysopidae - representatives of Neuropterans were registered on seeds. The largest number was noted in the 9 a.m.-1p.m., with maximum at 11 a.m.
Chrysopa carnea prevails among Chrysopidae. You can see single representatives of Lepidoptera on buckwheat crops throughout the day.
Complex of insect pollinators on buckwheat is quite dynamic. The greatest changes occur within the first half of the day, when many insects fly to buckwheat crops and back. Overlapping of feeding sources on buckwheat flowers usually occurs partly because insects which are on flowers vary in size, intensity of visits and time spending on them. Competition can arise only in bees, the number of which shall be regulated by the installation of a certain number of hives.
Besides insect pollinators there is large variety of insects-phytophags. About 30 species of insects feed on seeds, root systems and stems of buckwheat starting with the phase of sprouting and to budding [7]. Most of these species are terrestrial: representatives of the families of click beetles, and darkling beetles, scarabs, buckwheat or beet flea beetles. All of them damage in the larva stage. Some species of nematodes parasitize on the root stems. Most of these species are polyphags, and they food on buckwheat root system because this crop is dominant in comparison with weeds and insects have no choice of food. However, buckwheat is a crop of later sowing time, and this fact allows doing 2-3 cultivation before sowing. Cultivation helps to remove terrestrial pests to the soil surface, and then birds kill them, and reduce pest colonization.
Table 1 - Harmful insects of buckwheat according to various authors [8-14]
№ Pests of buckwheat Harmful stage of insect Kind of harm
1 Common mole cricket (Gryllotalpa gryllotalpa L.) Imago, larva Stripping of root system, base of stem
2 Italian locust (Calliptamus italicus L.) Imago, larva Rough chewing of the leaves, stems, flowers
3 Aphids: spindle tree (Aphis evonymi F.), buckthorn (A.nasturtii Kalt), beet (A. fabae Scop) Imago, larva Juice exhaustion
4 Trips (Anthothrips calthea L.) Imago, larva Juice exhaustion
5 Alleculid beetles (Meligethes aeneus F.) Imago, larva bugs feed on flowers, gnawing boots or leaves, larvae sometimes damage seeds and shoots
6 Leaf beetle (Cryptocephalus fulvus Goeze) Imago Feed on leaves of shoots and young plants
7 Buckwheat psylla (Aphalara colthae L.) Imago, larva Feed on leaves of shoots and young plants
8 Buckwheat flea (Chaetocnema concinna Marsh.) Imago, larva Feed on leaves of shoots and young plants, larva on root system
9 Black click beetle (Athous niger L.) Larva Destruction of seeds, root system
10 Snapping beetle (Agriotes lineatus L.) Larva Destruction of seeds, root system
11 Scarab (Lethrus apterus Laxm.) Imago, larva Bugs gnaw buds, leaves, young shoots
12 Cockchafer (Melolontha melolontha L.) Larva Destruction of root system
13 Chafer (M. hippocastani F.) Larva Destruction of root system
14 Scarab beetle (Anomala dubia Scop.) Larva Destruction of root system
15 Buckwheat weevil (Rhinoncus sibiricus Faust) Imago, larva Imago on leaves, larvae on roots
16 Striped hawk (Celerio livornica Esp.) Caterpillar Eating off leaves
17 Casebearer (Augasma aeratella Z.) Caterpillar Eating off leaves
18 Beet moth (Loxostege (Pyrausta) sticticalis L.) Caterpillar Eating off leaves
19 White -lined moth (Euxoa tritici L.) Caterpillar Eating off leaves
20 Turnip moth (Euxoa segetus Schiff.) Caterpillar Eating off leaves
21 Silver moth (Phytometra gamma) Caterpillar Eating off leaves
22 Orache moth (Trachea atriplicis L.) Caterpillar Eating off leaves
23 Cabbage moth (Barathra brassicae L.) Caterpillar Eating off leaves
24 Cabbage white butterfly (Pieris brassicae L.) Caterpillar Eating off leaves
25 Moth (Augasma aeratella Lell.) Caterpillar Eating off leaves
26 Midge (Stenodiplosis panici Plot.) Larva Inpour into flowers, feed on juice of flower chaff and on other parts of plants
27 Cranefly (Tipula palludosa Meig.) Larva Stripe root, stems and leaves of the young plants in spring.
The considerable part of buckwheat entomocenosis (about 40 species) is presented by species feeding on stalks and leaves of buckwheat. Seedlings are damaged by caterpillars of different moth - turnip, silver, and cabbage, orache, white-lined and other. The imago of buckwheat flea is more dangerous for seedlings. The larva of buckwheat midge damage leaves. Caterpillars of beet moth are of great damage for seedlings in the period of mass reproduction. Different kinds of trips, moths, leafhoppers damage buckwheat. Among polyphagans some species of nongregarious acridoid, grasshoppers, tettigonoid grasshoppers, Tipula paludosa, the Italian locust as representatives of gregarious were registered in the south-west of region.
Buckwheat flowers serve as food for blossom weevil, but a large number of bugs of other species can feed on generative parts: chafers (the golden - Cetonia aurata L., smelly -Oxythyrea funesta Poda. ),buprestids (Buprescidae),malachiid beetles (Melyridae), antlike flower beetles (Anthicidae), burbels (Cerambrycidae), alleculid beetles(Alleculidae), nitidulid beetles (Nitidulidae), ladybirds (Coccinellidae). As it was stated earlier by E.K. Grinfeld and
I.V. Issi, some anthophilous bugs systematically fly to flowers and feed on only pollen and nectar, and, practically don't damage flowers, others can do harm to flowers [7].
The number of pest insects on buckwheat crops doesn’t reach high density, however during the summer periods of 2002, 2010-2013, dry and hot weather during the first phases of buckwheat growth,when plants are less resistant to damages, but are attractive to pests, were favor for spreading of plant pests . Some fields were completely populated with plant aphids and their number reaches 150 on some plants. In recent years cases of increasing of damages of plant pests on buckwheat became frequent and it leads to sharp weakening of plants and productivity can be only 2-4 c/hectare [15]. The additional list (to table 1) of harmful insects of buckwheat, registered by us in the Orel region is presented in table 2.
Table 2 - Harmful insects registered on buckwheat crops in the Orel region
№ Pests of buckwheat Harmful stage of insect Kind of harm
1 Leafhopper - Macrosteles laevis Rib. Imago, larva Exhaustion of plants juice
2 Bugs Lygus: L. Pratensis L., L. Lugulipennis Popp., L. Gemellatus H.-s. Imago, larva Exhaustion of plants juice
3 Alfalfa plant bug - Adelphocoris lineolatus Gz. Imago, larva Exhaustion of plants juice
4 Notostria aruatica L. Imago, larva Exhaustion of plants juice
5 Desert com flea beetles - Claetocnema arida Fondr, Ch. Hortensis Geoffr. Imago, larva Imago on leaves, stems, larva -on roots
6 Black flea beetles - Phyllotreta atra F. Imago, larva Imago on leaves, stems, larva -on roots
7 Flea beetle - Ph. Undulate Kutsch. Imago, larva Imago on leaves, stems, larva -on roots
8 Striped flea beetles - Ph. Triolata Fabe. Imago, larva Imago on leaves, stems, larva -on roots
9 Striped flea beetles - Ph. Vittula Redt. Imago, larva Imago on leaves, stems, larva -on roots
10 Click beetles - Agriotes sputatos L. Larva Destruction of seeds and root system
11 Chrysomelid beetles: buckwheat Gastroidea polygoni L.and dock G.viriduls deg. Imago Feed on leaves
12 Lema lichenis Voet. Imago, larva Imago, larva on leaves and stems
13 Beet leaf bug - Poeciloscytus cognatus Fieb. Imago, larva Exhaustion of plants juice
14 Alfalfa bug - Coptosoma scutellatum Geoffr. Imago, larva Exhaustion of plants juice
15 Click beetle - Selatosomus aeneus L. Larva Seeds, seedlings
16 Dark - winged grasshopper - Stauroderus scalaris F.d.W. Imago, larva Eating off leaves
17 Oedaleus decorus Germ. Imago, larva Eating off leaves
18 Great green bushcow Tettigonia viridissima L. Imago, larva Eating off leaves
19 Agrotis ipsilon Hufn. Caterpillar Eating off leaves
20 Striped leafhopper - Psammotettix striatus L. Imago, larva Exhaustion of plants juice
21 Green leafhopper Cicadelia viridis L. Imago, larva Exhaustion of plants juice Exhaustion of plants juice
Control of pest species number is find out on the basis of monitoring, varying of sowing date, carrying out of agrotechnical and chemical (preventive) actions to combat weeds as food, attracting phytophags, the attraction of entomophags, the use of growth regulators, fertilizers, irrigation, and other measures which promote good state of buckwheat crops and for the creation of opportunities «to leave» from mass phytophags damages.
The described types of insects are the main part of the agrocenosis of buckwheat fields. They are the direct parts of the trophic relation «plant-insect». The relation «plant-insect pollinators» occurs, when insects carry pollen from one plant to another or to other field. The special group of insects of buckwheat agrocenosis is presented by species in imago stage, feeding on pollen or nectar, and in stage of larva (some species and in imago stage) - by other insects. Lady beetles, syrphids, soldier flies, lacefly, tachina flies and parasitic hymenopterans - belong to this group of insects.
About 25 species of insects, in larva stage and in imago stage only are indirectly related to buckwheat crops-carabid beetles and road beetles. As typical predators they feed on insects flying to buckwheat or living in agrocenosis. Pecularities of buckwheat cultivation, insecticide treatments absence, the species variability of entomocenosis, allow insects to find comfortable conditions for existence. They appear on the field in the first half of vegetation, and live there until ripeness and migration to other natural biocenosis begins only before harvesting
Non typical species of insects - ants, leaf beetles, pea weevils, and other who also can have food preferences and populate buckwheat agrocenosis can find temporary shelter with food in this agrocenosis.
CONCLUSIONS
Agrocenosis of buckwheat field is unique in modern crop rotations according to attraction and a persistence of various insects. Insects that live in it can be divided into several groups. The first and the largest group is represented by pollinators and feeding on flowers. They feed on nectar, pick it and help pollination: bee honey, wild bees, bumblebees, wasps, other hymenopterans, dipterans, coleopterans and other. All of them are polytrophic and fly to many flowering plant species, including buckwheat. The second group - insects feeding on flowers pollen, nectar and generative organs. Due to the peculiarities of nutrition and behavior on the flowers they are pollinators, but sometimes they can do them damage. Such beetles as scarab beetles, barbells, some species of leaf beetles and alleculid beetles belong to this group.
The third group of insects whose imagos feed on flowers and larvae (and sometimes imago) parasitize on buckwheat phytophags and on other fields and natural biocenosis. Coccinellidae, lacewings, syrphid flies, tachina flies, phasiae, parasitic hymenopterans belong to this group. These insects need not only buckwheat plants, but also its phytophags that serve them as food for their larvae.
The fourth group of insects-phytophags, feeding on sown seeds, root systems, seedlings and vegetating plants until harvesting.
The fifth group of insects - real predators, mainly from carabid and road beetles families.
The sixth group is insects, casual visitors of buckwheat agrocenosis.
The most mass species of insects are pollinators-hymenopterans and first of all, bee honey, then coleopterans, and dipterans. The number of harmful insects-phytophags can sharply increase in some years, it depends on the weather conditions, favorable for their evolution. In our region they are aphids, beet webworm.
Relations between insects living in buckwheat field with other components of the ecosystem are mainly trophic (direct and indirect): «plants - insects phytophags»; «plants insects phytophags - entomophags», «insects «neutral» - entomophags»; and phoria: plant -insect pollinators. Topical contacts arise under the influence of plans, which determines the existence conditions of pest and entomophags (buckwheat crops as a habitual area for insects with opportunity for meetings of genders, reproduction and habitation of different
generation stages). Undoubtedly, there are other relations between insects in the biocenosis of buckwheat, for example, with weeds, pathogens (entomophthorales fungus, phytopathogenic, viruses), and other organisms inhabiting the biotope. Insects can transmit buckwheat diseases. It is important to continue studying the reaction of insects to changes of environment conditions, to the effect of abiotic, biotic and anthropogenic (technological) factors in different combinations and intensity. These studies allow controlling the state of the agro-ecosystem of buckwheat better, using its potential not only as a bee plant, but also as a biotope, favorable for conservation of the diversity of entomofauna and help to increase harvest and its quality.
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