Let's talk about wood lice today.
Citrus lice are a genus of hemiptera Pyllidaceae, which mainly harms plants of the family Rubiaceae.
For example, citrus, grapefruit, yellow peel, nine incense, goji berries and oranges can be used as host plants for citrus psyllids.
Wood lice are the most harmful in citrus and are the main natural vector for the transmission of citrus dragon disease.
Citrus xanthosis is one of the most devastating diseases in the production of citrus in the world, once plants are infected with this disease, there is no rescue measure, so strict control of citrus lice is currently a key measure to prevent and control citrus xanthosis.
In recent years, many researchers in China have mainly done a lot of research on the occurrence law, living habits and control methods of citrus psyllids, and have made gratifying progress.
The growth process of wood lice
1. What does a wood lice look like?
Note that this is the case with wood lice on tea leaves.
Wood lice also appear on grapefruit, so be sure to pay attention!
The larvae and adult forms of wood lice are not the same.
The adults of the wood lice are shown below:
How are the yellow dragon disease bacteria divided in the body of the psyllid?
The pathogenic bacteria of Huanglong disease can live in the body of the pyllid, and when the fungal pyllid feeds on the healthy strain, the pathogen can be introduced to the plant through the mouthpiece, and settle, multiply and expand in the plant.
Ren Suli used a bright field of view channel to determine the division of Huanglong disease bacteria in the body of the psyllid as shown in the figure above.
Citrus psyllids are the main pest of citrus, which mainly harms new shoots and shoots. It is harmful to adult and nymph clusters on young shoots, young leaves and new shoots, resulting in young shoots withering, new shoots bending, young leaves deformation and distortion, and the white secretion of nymphs commonly known as "dense dew", which can cause coal pollution on the branches and leaves, affecting the photosynthesis of the plant.
Autumn and late autumn are the outbreak periods of wood lice, so be sure to pay attention!
Someone has done research on psyllids:
1Are wood lice sensitive to color? Can I use color to catch it all?
Citrus lice have a higher tendency to yellow plates when the mouth density is higher, and the tendency response to color is not obvious when the population density is low.
2. Is it possible to use what drives the lice away and makes it hate the citrus grove?
Neem oil, neem oil and neem have obvious repellent effect on citrus wood lice, and the essential oils of 5 kinds of plants such as coriander, ma yingdan, tortoise chrysanthemum and false stinkweed also have obvious avoidance effect on citrus wood lice, and the essential oils of 5 kinds of plants such as coriander, lavender, rose, thyme and tea tree have repellent activity on citrus wood lice, and spraying on citrus leaves such as garlic and onions also has a tendency to avoid citrus lice. Some people say that intercultured guava can reduce the number of lice lice populations and reduce the incidence of yellow dragon disease, but I think this does not have much effect, it will only bring more fruit flies, avoidance is only alleviated, hungry what not to eat?
3. What is the effect of temperature on psyllids?
Temperature has an impact on the psyllid, continuous low temperature in the winter, citrus psyllid cold tolerance will weaken and poor mobility, if killed by spraying during this period, can effectively reduce the source of spring insects. However, in recent years, with the global warming and the winter temperature rising year by year, the population of citrus psyllid has expanded significantly, and its geographical distribution has also spread northward year by year, exacerbating the spread rate and harm range of citrus dragon disease.
4. What is the effect of light on psyllids?
Light also has an impact on the natural growth of citrus psyllid populations. Light provides visual cues for citrus psyllids to select host plants, and light intensity and light time can affect egg laying and female mortality of citrus psyllids.
If the sun is sufficient in the orange garden, the light intensity is large and the light time is long, resulting in a high survival rate of citrus psyllids, frequent activity, and serious occurrence; however, if the plant is too dense or there is a shelter forest, resulting in small light intensity, short light time and low temperature in the orangery, the growth and development of citrus pyllids is delayed, the activity ability is poor, and the amount of occurrence is small.
5. How do wood lice move and get infected on citrus?
When there are plants infected with huanglongbing disease in citrus orchards, nymphs aged 3 and above in citrus plants move significantly between the young shoots in the vertical and horizontal positions of citrus plants, but the transfer speed on the disease-susceptible plants is slower than on the healthy plants, and the transfer speed between the young shoots is affected by the density of the insect mouth, the higher the density, the faster the transfer speed, and the nymphs tend to be disease-sensitive plants during the horizontal position transfer process. In addition, the phenomenon of psyllid nymphs on healthy plants has obvious migration to the lower part of the plant, and the number of nymphs transferred to the lower part is significantly higher than that of the disease-susceptible plants. Therefore, the spread law of psyllid nymphs and the influence of disease-susceptible plants on the transfer and spread of citrus psyllids have important guiding significance for the prevention and control of citrus psyllids and yellow dragon disease.
6. Since the yellow dragon disease bacteria can be in the body of the pyllid, what other bacteria can be used in the lice of the lice, can it be killed with this bacterium?
There are 10 bacterial genera in citrus psylli, including Bacillus spp., Irvingia spp., Klebsiella spp., Staphylococcus spp., Tynobacterium spp., Panbacterium spp., Pectin bacillus spp., Salmonella spp. and Streptomyces spp., of which Bacillus aerophilus is the resident dominant bacteria in Pyllidum. Studying these bacteria is also one of the pathways.
7. How long do wood lice suck diseased trees?
Citrus psyllids have a short time to obtain the pathogen of huanglong disease, and the pathogen can be detected within 1 hour of feeding on the phloem of the diseased tree, and the nymphs and adults can obtain the bacteria, and the nymphs have the strongest ability to obtain bacteria. But the eggs of psyllids do not carry germs.
8. How long are the yellow dragon disease bacteria in the body of the pyllid?
Adult first-feathered citrus psyllids are picked up on diseased citrus trees at 15, 30, and 45 days, respectively
Citrus psyllids at different feeding times are collected for 60 days for testing. The results showed that the content of yellow dragon disease bacteria in citrus psyllids reached the highest level during 15 days of feeding, and then decreased with the further prolongation of the feeding time.
9. How to prevent and treat huanglongbing disease?
Three-plate axe: cut down diseased trees, prevent wood lice, disease-free seedlings and scion
Many times, the wood lice have already laid their eggs on the tender slightly, and when the young one is slightly withdrawn, the eggs of the wood lice begin to hatch into small wood lice, especially in the Guinan area, the occurrence of wood lice is more than aphids.
These are the larvae of the wood lice, and they are very different from the adults, just like the small tadpoles become frogs, the wood lice in the larval period are not flying, but they can move.
The appearance of the psyllid hatching from the egg into a larva, I looked like an armored warrior at first glance, it was very good-looking, but the harm was quite terrible.
Morphological changes in citrus psyllid 5-year-old nymphs
Wood lice and aphids are mixed together, and sometimes there are ants, which are suckers of honeydew secreted by wood lice and aphids.
The unmanaged orchard is like this, bare and tender, lined with the larvae of the wood lice.
When the wood lice become adults, they will jump and fly, and if you squeeze it with your hand, it will not die, and when you let go of your hand, it will fly away.
After adult wood lice eat citrus infected with yellow dragon disease, it has yellow dragon disease bacteria in its body, at this time, if they fly to a healthy citrus tree to suck sap, the healthy citrus tree will get yellow dragon disease.
Photographed around Nanning on March 22, 2017.
The orchard will eventually be cut down, because the fruit is deformed and smaller, the taste is light and tasteless, there is no commodity value at all, and the tree is yellowed and decadent, and the production capacity is reduced.