Fifth Pest Surveillance

 

Time: 11: 30 AM

The day was warm and sunny today. We performed our final pest surveillance today, the sky was partly cloudy with the temperature reaching 27° Celsius and relative humidity recorded at 48 %. The cauliflower plants have grown a lot, but the growths were not uniform. The weather over the week has been partly cloudy, marked by two light showers of rain and a steady increase in day temperature. As stated in the previous blog many fields below our sample field were cleared for new vegetable cultivation.

Our group decided to conduct a Blitz survey and record all the pests and insect predators encountered in the field. The major insect found were aphids and cabbage white butterfly larvae, about 56 aphid colonies were encountered and 88 ladybugs were spotted. Many aphids with wings were also observed. There were around 15 groups of cabbage white butterfly larvae. We noticed symptoms of red ant infestations as some plants were rapidly dying. About half a dozen grasshoppers were observed hopping from plant to plant. We saw few spiders too (Spiders were never observed in previous field visits). Harlequin bugs were found in few plants but not in high numbers. We also saw some diamond back-moths, like other bugs they were less in numbers. Although there were many pests, their combined damage can safely be summed up to be of a negligible amount. This can be attributed to the researcher’s hard work in keeping his field clean.

Fourth Pest Surveillance

10th March 2021

 As always at 10 AM, we conducted our fourth pest surveillance today, since last Friday the weather has been cool and mostly cloudy. There was heavy rain on Friday and it has been relatively cool for the past few days. There was some improvement today as clouds began to clear. It was a sunny day, the temperature was 21° Celsius and the relative humidity was 87 per cent for the area.

Like last time we opted for a blitz survey, considering the small size of our field. The prominent pest found in the field was aphids. The population density of each colony has increased to more than 80 aphids. There are around 30 aphid colonies, similarly, the number of ladybugs in the field has increased too there are 71 ladybugs. As reported last time, there are sporadic red ant infestations but limited to few plants and their symptoms can easily be identified by looking at the sudden wilting and death of cauliflower plants. The researcher has been promptly replacing sick plants especially the ones infested by red ants. The last pest that we found was eggs of cabbage white butterfly on the underside of the leaves, there were six batches of eggs. They were diagnosed as cabbage white butterfly eggs due to their conical and longitudinal shape and orange color eggs. The researcher promptly removed the eggs and disposed of them.

One interesting activity that we noted was that fields lying below our field were cleared, ploughed and readied for other crop cultivation. These cleared fields had Cole crops.

Third Pest Surveillance 03-March-2021

Today at around 10 AM, a week after our second pest surveillance, we performed our third pest surveillance. In the past few days, we felt a gradual increase in temperature here in the Lobesa area. Marked by some light rains, the sky has been partly cloudy most of the time with light showers on two occasions (Saturday and Sunday). However, with the gradual increase in temperature, there has been a noticeable increase in relative humidity too. It was partly cloudy today, with high humidity at around 89% and the temperature from the installed thermometer on the field was 18° Celsius. We learned that our field was 200 Meter square big. The cauliflower seedlings have matured significantly.

Considering the change in weather, we decided to perform a blitz survey today. After a thorough inspection, we found more than twenty aphid’s colony, almost all the colonies were feeding on young shoots (new growths). The population density of each colony was more than 60 aphids and consequently, there were about 64 adult ladybugs in the field. We also noticed few plants with stunted growth and rapid wilting symptoms, upon digging the root part we found heavy red ant infestation. These ants were easy to diagnose because of their reddish-brown colour. They were reported to feed on seedling roots of cole crops. (NPPC, 2017). As reported earlier we noticed felled plant parts on many beds, as suspected these were obvious damages of cutworms. We found cutworms on many beds, even though the researcher has been collecting cutworms every morning.

References: National Plant Protection Center.(2017). Pests of Bhutan. http://pestsofbhutan.nppc.gov.bt/

Second Field Visit

On 24th February at around 10 AM, exactly a week later we visited the same field again. This time our objective was to perform a blitz survey and make a list of all the pest we might detect today. As it’s a research field the field was clean and neat, the sky was clear and sunny and it didn’t rain for the last one week. The researcher had installed a thermometer too, the temperature at that moment was 20 °Celsius. The cauliflower seedlings has grown by few inches. We divided ourselves in groups of two and inspected the field.

We observed more than ten colonies of cabbage aphids spread across the field. Each aphid colony had more than thirty aphids and discoloration of leaves surrounding the aphids was also noticed. Like previous observations the aphid colonies established their colonies on ventral side of the leaves. The fields surrounding this field also reported numerous cabbage aphid infestation and an increase in lady bug population. The bunds between the upper and this field had conifer plants (Esp. Bidens pilosa) which could be an alternate host. We also counted more than fifty lady bugs. Some red ants had damaged a cauliflower plant and upon closer inspection we found red ants. A heavy infestation of cut worm was also observed, about twenty cut worms were counted. There were obvious signs of cutworm damages on some plants, as there were sliced trunks lying around on the beds. A green shield bug in one of the plants was observed too.

References: National plant protection centre. (2017). Agriculture pest surveillance manual.

First Pest Surveillance of Mini farm in CNR.

17th, February 2021

At around 11 am today we visited the mini-agri farm to conduct our first pest surveillance. As it’s our first pest surveillance we formed an objective and tried to use Agriculture pest surveillance manual published by National Plant Protection Centre (NPPC). Our main objective for today was detection of pests in the field. The type of pest surveillance system we followed here was specific survey as it involved an on farm activity. 

We had a clear sky with sunny day today, there was a light shower couple of days ago. The temperature was 15 degree Celsius and it is spring time of the season. The field we selected is a well maintained field, as it is a research field. The field has raised beds and cauliflower for research were planted on it, and it was fenced with green nets.

Close up of Aphids

The type of sampling method we employed today was full sampling method considering the size of our field. The cauliflower plants are still in seedling stage. After thorough inspection we detected a small colony of adult cabbage aphid feeding on a cauliflower plant. We were able to diagnose it after noticing the grayish and waxy appearance of the aphids. The aphids were located on the ventral side of the cauliflower leaf. The number of aphids detected today is below 50. There was discoloration of the area around the aphids. We also noticed a lady bug roaming around, probably hunting for aphids. As it is a clean field we did not find other pest.