Download Advantages and Disadvantages of Abamectin,The Comparison of

Advantages and Disadvantages
of Abamectin
Abamectin is bio-pesticide, which can be mixed with a variety
of insecticides or add a small amount of detergent that help
moist abamectin powder and increase its adhesion to improve
efficacy. It cannot be mixed with fungicides, or most of
biological pesticides are fungi which are the main ingredient
of abamectin would be killed by fungicides, then the pesticide
loses its effect; it can not be mixed with alkaline pesticides
as the most fungi in the drug live in acidic conditions that
alkaline pesticides will destroy the habitat of these
microorganisms, causing inactivation of fungi, pesticides
failure.
The first advantage of abamectin is efficient and can kill a
variety of pests, including lepidoptera, diptera, homoptera,
coleoptera insects, spider mites, rust mites, and also
effective at killing a variety of parasitic nematodes; second,
unlike the potency of other pesticides, it is not easy to
cause drug resistance; third, because the medicament sprayed
onto the surface of plants can quickly decompose, it is safer
to the predators, less pollution to the environment, and the
plant will not cause injury even with more than 10 times the
amount of usage.
Cons: first, abamectin kill pests slowly that it takes 2 to 4
days from slow movement to food refusal to death, so farmers
tend to think that the efficacy is bad; second, the original
drug is of high toxicity that various pesticides keep the
content of the active ingredient very low to reduce the
toxicity, but safety use is still needed.
Abamectin cannot be abused though it is a good medicine.
Currently it is expensive, usually utilized in vegetable
fields for the control of diamondback moth, cabbage worm,
leafminers, armyworm, spider mites, mites; on the fruit trees
for prevention and treatment of a variety of rust ticks,
fleas, aphids, mealybugs and lepidopteran pests; and pests
difficult to control with other agents or pests have anti-drug
resistance to other common agents such as spider mites and
cotton bollworms. It is should be the second choice as long as
other pesticides are useful, which can be considered as a sort
of environment protection.
In recent years, a series of mixing pesticides containing
avermectin have been developed such the one mixed with kinds
of pyrethroids agents or chlorpyrifos, etc., are often able to
accelerate the death of pests; increasing the tags or other
modes of action; delaying the drug resistance, worth to be put
into applications.
In addition, from the development of varieties, there is one
called emamectin benzoate, another similar drug called
methylamineavermectin which has higher insecticidal activity
than abamectin and it’s confirmed by tests, less toxic to
humans and animals, having a good application prospect.
The insecticidal activity of abamectin is 5~50 times higher
than the conventional pesticides, only 0.1~0.5g active
ingredient per mu for the usage amount. There are 84 species
of abamectin insecticide spectrum, which can effectively
prevent diptera, homoptera, coleoptera, lepidoptera pests and
a variety of mites. In the first alternative varieties of
highly toxic pesticides, avermectin is recommended for the
prevention and treatment of rice leaf roller and cotton spider
mites; emamectin are recommended for bollworm moth and small
levin. It is noteworthy that the ministry ofagriculture is
organizing experts to demonstrate for the recommendation of
avermectin applications in the fields of rice. If all goes
well, the forbidden use of avermectin which has lasted for a
long time will no longer be a problem.
The Comparison of Emamectin
Benzoate and Abamectin
Emamectin benzoate is a new type semi-synthetic antibiotic
effective insecticide abamectin B1 from the fermentation
product synthesis, ultra-efficient, low toxicity (nearly nontoxic formulations), no residue, pollution-free, just like
other biological pesticides, compared with avermectin, firstly
its insecticidal activity is higher by 1-3 orders of
magnitude, extremely strong against lepidoptera pole larvae
and many other pests and mites, of both stomach toxicity and
contact toxicity, very effective at very low doses
(0.084-2g/ha), and unharmful to beneficial insects, beneficial
for the comprehensive control of pests. In addition, it
expanded the insecticidal spectrum and reduced the toxicity to
humans and animals.
We know that emamectin benzoate is an upgraded avermectin
product, and its activity is much higher than avermectin, such
as its stomach toxicity is 2146 times as avermectin. So in
general, emamectin benzoate is far more effective than
avermectin, and it’s supposed to have better effect than
abamectin on diamondback moth control. But we found a strange
phenomenon during production, that is, avermectin is better at
diamondback moth prevention than emamectin benzoate, why?
Another important property of avermectin series is involved
here, that is the positive temperature coefficient rule.
Simply put, avermectin series of insecticidal pest virulence
(especially stomach toxicity) increases with increasing
temperature. However, emamectin benzoate is inconsistent with
avermectin in terms of virulence increasing along with
temperature: when the temperature is 16°C, the activity of
emamectin benzoate is 2-3 times as the same content of
avermectin; when the temperature is 16°C~22°C, the virulence
of avermectin (all referring to stomach toxicity) increased by
about six times while the virulence of emamectin benzoate only
increased 2-3 times, that is the same content (pay attention
that it is the same content) avermectin and emamectin
virulence is actually comparable when the temperature is about
22°C. But we know that the use of avermectin level for
production is generally higher than emamectin (emamectin
benzoate mostly at 1% or 0.5% while avermectin at generally
1.8% or 2%) , and the dilution ratio of emamectin benzoate is
generally higher than avermectin (1000-1500 times for
avermectin, 2000-3000 times for emamectin benzoate), that led
to the effective use of content in avermectin is actually much
higher than emamectin benzoate; as a result, the effect of
avermectin seems to be superior to emamectin benzoate at about
22°C.
As the temperature rises to above 25°C, the virulence of
emamectin benzoate is greatly increased, even increased by
more than 1,000 times while the virulence increase of
avermectin is limited (by a range from several times to 10
times), when the advantage of emamectin benzoate can really be
brought into full play. Leaf borer usually occurs above
28-30°C, so the effect of emamectin benzoate should be much
better than the avermectin to prevent leaf borer. Spodoptera
generally occurs at the time of high temperature and drought,
which is the annual July~October period (midsummer), so the
effect of emamectin benzoate is undoubtedly far better than
avermectin.
Analysis
of
the
Effect
of
Abamectin Used in Plant Roots
In China, many vegetable growers reflect that abamectin has
little effect on prevention meloidogyne, and some farmers even
say there is no effect at all. However, studies have shown
that abamectin has a strong repelling and killing efficacy on
root-knot nematode, ectoparasites and other arthropods. Why do
vegetable growers say it doesn’t work?
Through exchanges with some vegetable growers, Chinese
researchers learned that the poor effect of avermectin was
related to their use. Many vegetable growers felt that
spraying avermectin to the roots very troublesome, so they
just let avermectin flow with water into the ground, in order
to control root-knot nematodes, which the effects must be
greatly reduced in such a way, because avermectin need using
1500-2500 multiples times to ensure its effectiveness. That
is, every cubic meter of water needs about one pound
avermectin, for such a large amount, few farmers can make it.
Once less than this concentration, it is difficult to give
full play to the role of averment, which is the reason why the
vegetable growers reflect the poor effect of avermectin
control on root-knot nematode.
According to information that not only abamectin avermectin,
but there are a lot of other pesticides (mostly used for
spraying the roots), which farmers use to flush with water
that actually, is just a waste of pesticides and the effect is
not good as it is difficult to control the working
concentration of pesticide by water flushing which is hard to
control the water flow and to calculate how much pesticide
should be filled, so farmers can only do the spraying in an
approximate concentration range, once fail to reach the
optimal concentration range, then the effect would be
difficult to guarantee.
Furthermore, the cost of pesticide for spraying roots is quite
high. For a time of moderate quantity watering, about 20 tons
of water per acre, you need 40 kg pesticides if the effective
concentration of the drug is 500 times; If it is 2000 times,
you also need 10 kg pesticides, in this way the cost of buying
pesticide becomes a big deal.
In addition, flushing pesticide with water increases the
pesticide residues in soil. If the pesticide flushing is all
year round, the excessive pesticide residues in soil will then
break the balance of soil microorganism, the harm existing for
a long time, and it is also difficult to estimate the
potential problems.
In this regard, here is the reminder for vegetable growers
from the researchers: When using pesticides, you must operate
strictly according to the instructions, for instance, to
prevent root knot nematode with avermectin, it is preferably
to use monoclonal irrigating cooperating with chitin in the
growing season spraying, using 1000-1500 times avermectin
liquid, 250 ml per plant irrigation. This can ensure its
concentration, and cause no waste.
Use 1.8% avermectin EC. In order to prevention root knot
nematodes, you need full spray the soil surface evenly before
planting with per square meter 1 to 1.5 ml potion, diluted
into 2000-3000 times, then immediately rake into 15-20 cm of
topsoil, seed or plant after fully mixed. According to the
test and production application, it shows that 1.8% avermectin
EC has an effect up to 65%~88% on root knot nematode disease
control. But in some places, the defending efficiency
decreased for years of continuous use. Other soil
sterilization techniques should be matched with or used
alternately. Besides, among not a few avermectin mixed
pesticides on current market, the effective composition
content (for preventing and controlling of root knot
nematodes) of these mixed pesticides is very low, and the
survey found that the abamectin insecticides some producers
provide are of very poor efficiency.
The Reason for the Rapid
Development of Abamectin
Abamectin also known as avermectin,
has been well developed
in recent years; experts say that avermectin will have a good
development potential and prospect in the future. Well, why
avermectin can get such a good development? Based on what?
Avermectin is a mixture of natural fermentation, occupying an
important position in China pest control system. Currently
there are more than 10 enterprises producing avermectins. The
commercially available avermectin series on market are
abamectin insecticide, ivermectin, eprinomectin and emamectin
benzoate salt, etc. The fine avermectin is a kind of white
crystalline powder, mp 155-157℃, due to no acidic or basic
functional groups on its structure, which is stable under
normal conditions, do not decompose in the PH = 5-9(it will
decompose if there is light).
Avermectin is a nerve poison, acting on the mechanism of
insect neuromuscular synapse or synaptic GABAA receptors, to
interference messaging insect nerve endings that stimulate
nerves to release neurotransmitter inhibitors γ-amino butyric
acid (GA-BA), prompting GABA-gated chloride channel to extend
the opening of the chloride channel with activation, resulting
in a large influx of chloride ions nerve membrane potential
hyperpolarization, resulting in the inhibition of the nerve
membrane, thereby blocking the contact between nerve not tips
and muscles; as a result, insects become paralyzed, food
refused, then dead. Because of its unique mechanism, there is
no cross-resistance with commonly used pharmaceuticals.
It is reported that, in
addition to the GABA receptor chloride channel control,
avermectin can also affect other ligand-controlled chloride
channels. At the same time, avermectin has good layer shift
activity which means that avermectin can penetrate the leaf
tissue after crop spraying, forming a thin-walled sac in the
epidermal cells for long-term storage, so avermectin can have
a long-lasting effect. Because of its good level shift
activity, making avermectin more effective than conventional
drugs on pests difficult to control such as pest mites, leaf
miner, leaf miner and borer pests or sucking pests. What is
more, avermectin biodegrades easily in soil and water, then
absorbed by the soil without leaching or residue, having no
harmful effects on the environment; nor accumulating
persistence of residues in bodies, hence it’s supposed to be
pollution-free pesticides.
Avermectin can also be decomposed into derivatives with higher
activity by the soil microorganism, like the insecticidal
effect on plant nematodes. Now China has more than a dozen
manufacturers of avermectin, the annual production capacity
being 200-800 t/Y, but their skill levels are different, that
the gaps mainly focus on the fermentation contamination rate
and potency. Chinese abamectin suppliers titers are generally
around 3500μg/ml, individual manufacturers reaching more than
4000μg/ml; the contamination rate is generally below 10% while
one or two can keep it under 3%. It’s lately reported that the
newly breed bacteria with higher activity cultivated by a
institute can achieve 8000μg/ml in potency, which is highly
concerned by various manufacturers that if this technology
gets industrialized, China’s overall technological level of
production of avermectin will be greatly improved, expected to
reach the international advanced level.
50% of avermectin produced in China is used for its downstream
products, 30% for export and 20% for a variety of
preparations. As the major existing bio-pesticide varieties,
avermectin is short of supply, which directly led to the
constantly rising price. So far the development of new
formulations avermectin has become an international hot spot,
which has many types of formulations, such as cream,
microemulsion, soluble granules, microcapsules, etc. With the
huge increase in its preparations usage, avermectin has been
recognized by the international market, especially in
developing countries, such as Thailand, Pakistan, India, where
the imports has increased year by year. As you see, avermectin
really has extremely broad prospects for development.
Unearthing key function of
plant hormone
Plants, like animals, employ hormones as messengers, which
coordinate growth and regulate how they react to the
environment. One of these plant hormones, auxin, regulates
nearly all aspects of plant behavior and development, for
example phototropism, root growth and fruit growth. Depending
on the context, auxin elicits a range of responses such as
cell polarization or division. In this week’s edition of
Science a team of researchers including Jiři Friml from IST
Austria and led by Zhenbiao Yang of the University of
California, Riverside, report finding the molecular mechanism
by which the plant hormone auxin affects the organization of
the cell’s inner skeletons.
Plants like these trees on the campus of IST Austria rely on
auxin. This plant hormone regulates nearly all aspects of
plant behavior and development.
Credit: © IST Austria / Photo by Roland Ferrigato
Auxin is a remarkable molecule, impinging on a variety of
plant responses in growth and development. How auxin can play
such a range of roles is as yet unexplained, though auxin may
activate distinct signaling systems in different contexts and
so convey different signals for different responses. For
example, a nuclear receptor pathway modulates gene
transcription in response to auxin. Auxin binding protein 1
(ABP1) has been proposed to act independently of this nuclear
pathway, regulating responses at the plasma membrane and in
the cytoplasm. ABP1 was discovered nearly 40 years ago, but
how it transmits the auxin signal and regulates responses
remained unclear to date. In their Science publication, the
researchers show that at the cell surface ABP1 interacts with
transmembrane kinases (TMKs). In genetic variants of
Arabidopsis in which TMKs are mutated, pathways regulated by
ABP1 are impaired such as the characteristic arrangement of
pavement cells.
TMKs and ABP1 are also both required for the activation of ROP
GTPases, which regulate the organization of the cell’s inner
skeleton. This cytoskeleton is disrupted when TMKs are
mutated, as filamentous actin does not localize correctly and
cortical microtubules are disorganized. The researchers show
that all of TMK1 as well as around a quarter of ABP1 can be
found at the plasma membrane. In the presence of auxin, TMK1
and ABP1 bind to each other. The researchers propose that
secreted ABP1 binds to TMK1 at the plasma membrane in response
to extracellular auxin, and signal to ROP GTPases which affect
the cytoskeleton.
TMK1 is at least one of the long-sought docking proteins of
ABP1, which couple extracellular auxin and its perception by
ABP1 to downstream cytoplasmic events. Solving the mystery of
cell surface-cytoplasmic auxin perception, this research opens
up a new horizon in auxin biology.
Source:
Institute
of
Science
and
Technology
Austria.
“Unearthing key function of plant hormone.” ScienceDaily.
ScienceDaily,
28
February
2014.
<www.sciencedaily.com/releases/2014/02/140228103429.htm>.
Roots to
transport
shoots:
in
Hormone
plants
deciphered
Plant growth is orchestrated by a spectrum of signals from
hormones within a plant. A major group of plant hormones
called cytokinins originate in the roots of plants, and their
journey to growth areas on the stem and in leaves stimulates
plant development. Though these phytohormones have been
identified in the past, the molecular mechanism responsible
for their transportation within plants was previously poorly
understood.
Now, a new study from a research team led by biochemist ChangJun Liu at the U.S. Department of Energy’s (DOE) Brookhaven
National Laboratory identifies the protein essential for
relocating cytokinins from roots to shoots.
The research is reported in the February 11 issue of Nature
Communications.
Biochemist Chang-Jun Liu with Mingyue Gou, Huijun Yang,
Yuanheng Cai and Xuebin Zhang, whose work could lead to
sustainable bioenergy crops with increased growth and reduced
needs for fertilizer.
Credit: Image courtesy of DOE/Brookhaven National Laboratory
Cytokinins stimulate shoot growth and promote branching,
expansion and plant height. Regulating these hormones also
improves the longevity of flowering plants, tolerance to
drought or other environmental stresses, and the efficiency of
nitrogen-based fertilizers.
Manipulating cytokinin distribution by tailoring the action of
the transporter protein could be one way to increase biomass
yield and stress tolerance of plants grown for biofuels or
agriculture. “This study may open new avenues for modifying
various important crops, agriculturally, biotechnologically,
and horticulturally, to increase yields and reduce fertilizer
requirements, for instance, while improving the exploitation
of sustainable bioenergy resources,” Liu said.
Using Arabidopsis, a small flowering plant related to mustard
and cabbage that serves as a common experimental model, the
researchers studied a large family of transport proteins
called ATP-binding cassette (ABC) transporters, which act as a
kind of inter- or intra-cellular pump moving substances in or
out of a plant’s cells or their organelles. While performing
gene expression analysis on a set of these ABC transporters,
the research team found that one gene — AtABCG14 – is highly
expressed in the vascular tissues of roots.
To determine its function, they examined mutant plants
harboring a disrupted AtABCG14 gene. They found that knocking
out this transporter gene resulted in plants with weaker
growth, slenderer stems, and shorter primary roots than their
wild-type counterparts. These structural changes in the plants
are symptoms of cytokinin deficiencies. Essentially, the longdistance transportation of the growth hormones is impaired,
which causes alterations in the development of roots and
shoots. The disrupted transport also resulted in losses of
chlorophyll, the molecule that transforms absorbed sunlight
into energy.
The team then used radiotracers to confirm the role of the
AtABCG14 protein in transporting cytokinins through the
plants. They fed Carbon-14-labeled cytokinins to the roots of
both the wild-type and mutant seedlings. While the shoots of
the wild-type plants were full of the hormones, there were
only trace amounts in the shoots of the mutant plants, though
their roots were enriched. This demonstrates a direct
correlation between cytokinin transport and the action of
AtABCG14 protein.
“Understanding the molecular basis for cytokinin transport
enables us to more deeply appreciate how plants employ and
distribute a set of signaling molecules to organize their life
activity and for their entire body building,” Liu said.
“From a biotechnology view, manipulating the activity of this
identified transporter might afford us the flexibility to
enhance the capacity and efficiency of plants in energy
capture and transformation, and the storage of the reduced
carbon, or the ability of plants to adapt to harsh
environments, therefore promoting either the production of
renewable feedstocks for fuels and bio-based materials, or
grain yields to meet our world-wide food and energy demands.”
This work was completed in concert with researchers from
Palacky University & Institute of Experimental Botany, and St.
John’s University. It was funded by DOE’s Office of Science
and the National Science Foundation toward understanding plant
cell wall biogenesis and functions of ABC transporters,
respectively.
Source: DOE/Brookhaven National Laboratory. “Roots to shoots:
Hormone transport in plants deciphered.” ScienceDaily.
ScienceDaily,
20
February
2014.
<www.sciencedaily.com/releases/2014/02/140220132530.htm>.