Why dragon flies are important to Human beings?

Tweet

Buddha once said that human has more to study from butterflies than from text books. Same is the case with dragonflies, as far as ecologists are concerned. But why? Wonder why do the elite human race with well-developed brains at his command to survive natural challenges care such a weak creature?

Dragonfly resting on a leaf

The first reason is that they are just like us, living creatures. Let them live. But if you insist on getting benefits, there are many.

Best bio-indicators

Recent researches say that dragonflies, just like butterflies, are prominent indicators of ecosystem health. Any change in the ecosystem will first make a visible mark on dragonflies, be it the climate change or a chemical war.

For instance, some districts in the South Indian states of Karnataka and Kerala report large scale health issues among the people due to the areal spray of Endosulfan, a pesticide which is banned in many European countries. The adverse effect of the pesticide was not studied before starting its use. It grabbed media attention only when a doctor practicing in one of the villages noticed large number of cancerous abnormalities among his patients, years later.

But, the sign was visible very early, but nobody had the eyes to see it.

The area recorded an abnormal fall in the population of damsel flies and butterflies. They were the first creatures wiped out by the pesticide reaction. If an ecologist or nature lover detected the change and raised the alarm, they would have been able to avert many of the deaths (thousands of them, which still continue) in the area.

Any such changes to the ecosystem first reflect on these weak creatures. In South Africa, it was found that the species diversity of dragonflies directly relates to human disturbance and resulting degradation of an ecosystem. The dragonflies in the undisturbed areas were rare or endemic to that region while those found at the disturbed riparian patches were common or general in nature.

Biological Pest Control Agents

Damsel flies also offer important ecological services

 

Dragonfly larvae are known predators of larvae of mosquitoes and black flies which are vectors of fatal diseases. The adult dragonflies devour mosquitoes and similar blood sucking flies which carry diseases.

It has made them effective bio control agents against mosquitoes and insect vectors of some diseases. Granite Ghost (Bradinopyga geminate), a container breeding dragonfly is widely used in Thailand as a biological controller of Aedes mosquito which spreads dengue fever. Its use in the urban areas was proved effective in preventing dengue outbreak and spread.

Similarly, dragonflies help the farmers in pest control too.

Do you know anymore reasons? Share it with us here.

8 best practices to eliminate weeds in Conservation Agriculture method

Tweet

Conservation agriculture is a new method of agriculture which avoids the conventional methods of tilling the land before sowing the seed. Instead, it focuses on minimal soil disturbance and retention of residue to keep the moisture of the soil and to avoid erosion of manure and herbicides.

Maize under Conservation Agriculture in Malawi
Photo courtesy CIMMYT

 However, a major issue with the method is the presence of weeds. Following are some of the best practices to avoid weeds in conservation agriculture. However, they are modified to meet sustainable agricultural practices.

The methods avoid chemical herbicides as they cause environment pollution and turn less effective in long term.

1. Prevent weeds

·         Prevention is always better than herbicides. So make sure that you use clean crop seeds and machinery for seeding, harvesting and threshing, since many weed seeds actually reaches the seed bed in this way.

·         Keep field margins and irrigation canals free from weeds.

2. Stale seedbed techniques

·         Irrigate the seedbed lightly in advance so that the weed seeds which are often found in the soil surface germinate in two three days. Once they germinate in this period, first clear them off manually or using organic herbicides.

·         It is also advised to encourage seed predator insects or birds in the seed bed before sawing.

3. Adjust time of crop sowing

·         Make the crop sowing early in the season so that the crop gets a competitive edge over late germinating weeds.

·         This method has been proved successful in North India against certain weeds like Phalaris minor (Red Rice) when wheat crop was sowed early in the season.

4. Grow a cover crop which gives thick mulch

·         Grow crops like cowpea or sun hemp, which will produce thicker residue, between two main crops. Then cut down it before the main crop season.

·         The dead mulch of the cover crop not only helps retaining the moisture of the farm land, it also suppresses the weed germination by releasing allelo-chemicals and blocking sunlight which is needed for the seeds to germinate.

5. Use of narrow row spacing

·         Place crop rows closer so that they grow thicker, often blocking the sunlight to the space in between two rows, thus decreasing the chances of weed growth in between two consecutive crop rows.

Ground nuts under Conservation Agriculture
Photo courtesy CIMMYT

·         The space between two rows is a vulnerability of the conventional method which actually helps weeds, especially in maize and soya bean cultivation. Narrowing the gap between two consecutive rows can control weeds to a great extent.

·         15 centimeter row spacing is found very successful against P.minor.

·         Long term adoption of the method will bring down the availability of viable weed seeds in a seed bed.

6. Higher seeding rates

·         Increased crop density sometimes helps the crops compete better against weeds.

·         Higher seeding rate is proved to help in weedy or partially weedy seedbeds, though the method may not bring good yield in weed-free environments.

7. Use of weed competitive cultivar

·         The wild or traditional seed varieties which produce long shoot plants are more weed competitive though their yield is not on par with the short stature, high yielding modern seeds.

·         A continuous use of conventional weed-competitive cultivars coupled with narrow row spacing and other methods will bring down the weed presence and number of available weed seeds in a seed bed considerably if the farmers are ready to afford the decrease in production during a short term.

8. Adopting crop rotation

·         Crop rotation helps decrease certain crop specific weeds like P. minor in the case of rice or wheat crops.

·         Rotating the rice crop with a non-rice crop like maize or soybean can disrupt the lifecycle of such weeds.

·         Rotation the management practices also disrupts weed life cycle.

·         Crop rotation improves the soil quality too.

These methods are proved as effective weed management methods in conservation agriculture practices. Many of them are effective in other types of agriculture practices too. However, anyone of these methods when practiced alone may not bring a good result in eliminating weeds. But a brilliant coupling of different methods will surely produce a good result.

If you know any other weed management methods, share it for our readers in the comments.

Reference:
 Chauhan, B. S. & Mahajan, G (2012), Role of integrated weed management strategies in sustaining conservation agriculture systems, Current Science Journal, Volume 103, Issue 2, July 25, 2012, Indian Academy of Sciences, Bangalore, Retrieved from http://www.currentscience.ac.in/Volumes/103/02/0135.pdf on July 25, 2012.