Water Pepper Rivaled a Chemical Spray on Rice Grasshoppers

0:00 My name is Andrew and I am from Cameroon. This afternoon I will present to you my research on the comparison of chemical and bio insecticide in rice. This work has been supervised by Professor Se Chul Chun and Professor Doo Hwan Kim. My colleague has just presented the same rice where I am carrying out my experiment. So to save much time, I won't go into the details of the rice production, but I will present to you the technical aspects and the results of my experiment. So the rice crop is highly attacked by rice insects that generally cause more than 35%

0:51 yield losses, and these insects include the rice water weevil and termites, which are predominant root insects, and the stem borers that attack the stems. Meanwhile we have the leafhoppers, planthoppers and larvae and adults of beetles and grasshoppers that generally attack the leaves, and the stink bug is the common enemy to the rice grain. It's an example of a stink bug. So to test these pesticides, since morning we have been talking on the techniques of improving sustainable food. That is food that is environmentally friendly and healthy. All along we have been developing strategies. But

1:34 when the world will change and adopt natural farming, surely insects and other pests will also change the strategy to survive and how to move. They will also change the way they enter crops, and our natural farming products will be in danger. So it is high time we develop natural pesticides to ensure that our products will survive in the future. So to do this, I carried out two experiments. One was in Paju on natural rice farming and one was in Yeoju. So at the end, the results were compared and then I will present what I found.

2:12 So in experiment one, as I said my colleague was already presented the experiment on rice, so I will present only the salient points of the experiment. So in experiment one, we used bio-extracts which were obtained by boiling plant samples for 8 hours, diluting them to 1 to 15 ratio and applying as foliar sprays. And the following treatments we use: the plant extracts we use are red pepper and then lemon peels, from which we obtain the insecticide.

2:58 Then Persicaria longiseta, which is commonly called water pepper, and in Korea they call it yeokkwi. We equally use tobacco leaves. That is a tobacco. I just pay this chemical, this molecules, because I know maybe it will cause problems. These are the active ingredients in the chemicals that are responsible for the insecticidal effects of the products we use. So, I just present to you the plant species, and if there is someone who wants to know detail why the plant is an insecticide, maybe he can then follow up by reading more of it. And then the last one was neem oil.

3:47 So, when we obtain these extracts, we first tested the extracts in the laboratory to make sure that the extracts have insecticidal effects, that is that they could kill insects. And this was done by introducing 10 insects in a cage and then applying the extracts from the plants directly on the insects and observing them after some time and data recording. After carrying out the laboratory screening to make sure that the pesticides, the plant plant extracts are really insecticides, we now carried out a field trial where we tested these

4:24 plant extracts on the field and to do this we used 24 experimental plots of five by five meters each in two blocks of 12, and we applied six treatments replicated four times following a randomized complete block design, and treatments were applied at 15 ... 45, 60, 90 days, that's five times, and in the field we selected 12 hills per plot for growth data collection. Meanwhile, in experiment two, on conventional farming, that is where we use chemicals, we transplanted seedlings of Hopum rice variety at this density, and we supplied plant nutrients

5:08 using chemical fertilizers. We applied 4.5 kilograms of NPK fertilizers at 14 days after transplanting and 4.5 kilograms of nitrogenous fertilizers at 80 days after transplanting. We equally used herbicides for weed control. So these are the treatments we use at the conventional farm. We use a popular chemical insecticide in Korea known as Pyretan, which we diluted at 1 to 1000, and the active ingredient is cypermethrin. And then the second treatment was water pepper, or yeokkwi. The third treatment was neem oil and the fourth treatment was chili pepper. Those are the

5:56 concentrations we used with the chemicals. And we applied to the plants on these days, four times. Then we observed that in the laboratory evaluation screening test, laboratory evaluation of bio-pesticides, water pepper and tobacco leaves performed best, because after treating them with these substances for two days, all the insects in the cage where water pepper and tobacco were used, all of the insects died. But 20 percent of the insects were still remaining in the cage treated with chili and neem oil, while 60 percent of the insects were remaining in

6:46 the cage treated with lemon peel extracts. And in the control cage, where no insecticide was applied, all the insects were living, no insect died, showing that really the plant extracts we are using have insecticidal effects, that they can successfully kill insects. Then we proceeded to the field, and this was the result we obtained. In the field, after treatment, we observed that water pepper, tobacco leaves and neem oil were efficient in controlling these rice insect pests, that is rice water weevil, green grasshopper, rice stem borer, rice

7:30 stink bugs, than chili pepper and lemon. So from there we can see that these three extracts, water pepper, tobacco and neem, have better insecticidal properties. And in this field, one thing to remark is that there was the presence of beneficial insects. That is, we had a lot of dragonflies in the field, and spiders. We go ahead, you see the other piece. Then, when we compare the effects of these plant extracts on the growth of rice, we noticed that the plot treated with water pepper again produced shorter plants.

8:19 My friend just showed some plants which were lodged and some which were standing. So we see that when plants are very tall, they are not very good in rice because they can easily lodge. But water pepper produces shorter plants. And paradoxically, these shorter plants produce the highest number of tillers, as you can see, and the highest number of panicles than all other pesticides tested. So now, in experiment two, where we used the chemical insecticide cypermethrin and the other bio-pesticides,

8:58 we observed that water pepper in particular had a similar performance to cypermethrin, a chemical pesticide. That means water pepper can be substituted to cypermethrin if we can use it and have almost the same results. And when we look at the percentage of insects in the field, we see that in the plot where we use conventional, there are no beneficial insects which proves that the chemical pesticides are dangerous to the environment, to insects and to human beings as a whole. And that is why, in conclusion, we can proudly say now that

9:38 natural pesticides can successfully replace chemical pesticides and that neem oil, water pepper and tobacco leaves extract have promising insecticidal effects and can improve rice productivity in Asia and in other countries. Thank you.