Effectively reduce the pest damage rate of corn and sorghum by using pheromones wisely

TACTRI has actively promoted biological pesticides in the past two years and has developed more than 20 different pheromones-related products. Agricultural pests have always plagued farmers. Among them, the Asian corn borer and corn earworm (tomato armyworm) were the insect pests of corn and sorghum. At present, the major and minor corn pests are the Asian corn borer and beet armyworm, respectively, while the major pest of sorghum is corn earworm. These pests have caused serious damage to the cultivation of corn and sorghum in Taiwan, affect the yield and quality of corn and sorghum. In response to this, TACTRI set up sex pheromone traps for the above-mentioned pests in corn and sorghum fields. The results showed that sex pheromones mass trapping can effectively reduce the pest damage rate.

Maize and sorghum are closely related gramineous crops. The planting area of ​​edible corn in Taiwan is about 15,000 hectares, mainly in Yunlin, Chiayi and Tainan; the planting area of ​​sorghum is about 2,000 hectares, and the main producing area is Kinmen. The major corn pest is the Asian corn borer while the minor pest is beet armyworm. The major pest of sorghum is corn earworm. The Asian corn borer will burrow into the ears and stalks of the corn, and the beet armyworm will spin and feed on the corn seedlings, stop the corn leaves from expanding; the corn earworm will feed on the ears of sorghum. All above will seriously affect the yield and quality of corn and sorghum and caused major losses.

In this regard, TACTRI cooperated with Taiwan Agricultural Research Institute to evaluate the effect of mass trapping with sex pheromones on corn in spring and autumn respectively. Pheromone traps were set at the amount of 40 per hectare for Asian corn borer, 20 per hectare for beet armyworm from the seedling stage of corn till corn was harvested. The traps were arranged in concentric circles in the fields. The mass trapping test area was sprayed with Bacillus thuringiensis for only once to control the Asian corn borer in fall corn field. The results show that mass trapping treatments can effectively reduce the population density of the Asian corn borer and beet armyworm(less than 10 insects/trap, surveyed every 2 weeks), and greatly reduce the damage caused by the Asian corn borer. The damage rate of spring corn done by Asian corn borer was reduced from 92.7% in the control area (conventional cultivation area) to 17.1%; damage rate of fall corn was reduced from 54.7% to 3.4% and 18.1%, with an average reduction in the damage rate of 54.6%.

The test results show that mass trapping Asian corn borer and beet armyworm  using sex pheromone traps in corn fields can not only reduce pesticide application, but also effectively reduce the damage of corn plants caused by Asian corn borer. A conservative estimate of the output value per hectare of corn can be increased by another 43,500NTD. In addition, when TACTRI cooperated with Kinmen County Animal and Plant Disease Control Center in conducting a sex pheromone trapping test, it was found that the corn earworm in Kinmen is geographically different from the same species on Taiwan Island. In order to control the pest, TACTRI has modified the sex pheromone component for this pest in the Kinmen area to benefit local farmers. According to TACTRI, with the appropriate use of sex pheromones to control pests they can effectively reduce the use of chemical pesticides and ensure environmental friendliness and safety.

Corn Earworm on Sorghum (from Kinmen Agricultural Research Institute)

Sex pheromone formula test on corn earworm

Asian corn borer damage on corn、

They effectively reduced the population density and damage when the sex pheromone traps using for mass trapping insect pests were arranged in concentric circles in field.