The Effects Of Host Plants And Abamectin On Oviposition And Feeding Behavior Of Plutella Xylostella (L.)

The purpose of this experiment was to study the effect of cruciferous plants and biopesticide abamectin on oviposition and feeding behavior of DBM, and the reasonable refrigerated time of DBM eggs and pupae. At the same time, it improved the breeding methed of DBM. The results are as follows:1. The effect of refrigeration on DBM4℃, the hatching rate of DBM eggs generally decreased with the increasing of refrigerated time. When refrigerated time reached30days, the average hatching rate decreased to26.5%, but when refrigerated time was10days, the average hatching rate was the highest. The emergence rate of pupae decreased with the increasing of refrigerated time. When refrigerated time reached25days, the average emergence rate decreased to27.3%; The number of eggs decreased with the in creasing of refrigerated time. When refrigerated time reached15days, the average number of eggs decreased to33.0, When refrigerated time reached20days, DBM didn’t oviposit any longer.2. The oviposition selectivity and feeding selectivity test of DBMDBM tended to oviposit on the bok choy(Brassica rapa L. Chinensis Group.) and rape seedlings, didn’t like oviposit on the cabbage(Brass/ca oleracea L. var. capitata L.) and broccoli(Brassica oleracea L. var. boteytis DC) seedlings. Indoors, DBM larvae liked eating the rape seedlings the most, then the mustard(Brassica juncea Czern.), bok choy, Chinese flowering cabbage(Brassica campestris L. ssp. chinensis var. utilis Tsen et Lee) and cabbage seedlings, didn’t like eating the radish(Raphanus sativus L.) and broccoli seedlings; In the fields,DBM larvae liked eating the rape seedlings, then the mustard seedlings, didn’t like eating cabbage, radish, bok choy and broccoli seedlings.3. The effect of abamectin on oviposition selectivity of DBM10pairs DBM adults oviposit299.17on the bok choy seedlings without spraying abamectinon average, oviposit92.17on the bok choy seedlings spraying abamectin on average. There was a significant difference(p<0.05); The average ratio of egg number was1.42when there was n oabamectin on the bok choy and rape seedlings. The average ratio of egg number was0.42wher there was abamectin on the bok choy seedlings but there was no abamectin on the rape seedling There was a significant difference(p<0.05). The average ratio of egg number was19.43when ther was no abamectin on the bok choy and broccoli seedlings. The average ratio of egg number wa4.48when there was abamectin on the bok choy seedlings but there was no abamectin on th broccoli seedlings. There was not a significant difference(p<0.05).4. The effect of abamectin on feeding selectivity of DBMIndoor test:10DBM larvae ate447.33mm2on the rape seedlings without spraying abamectii on average, ate157.17mm2on the rape seedlings spraying abamectin on average. There was a significant difference(p<0.05). The average ratio of feeding area was1.96when there was n abamectin on the rape and mustard seedlings. The average ratio of feeding area was0.42wher there was abamectin on the rape seedlings but there was no abamectin on the mustard seedlings The averageratio of feeding area was40.75when there was no abamectinon the rape and broccoli seedlings. The average ratio of feeding area was2.02when there was abamectin on the rape seedlings but there was no abamectin on the broccoli seedlings. The differences were significan (p<0.05).Field test:20DBM larvae ate719.17mm2on the rape seedlings without spraying abamectin on average, ate346.67mm2on the rape seedlings spraying abamectin on average. There was a significant difference(p<0.05). The average ratio of feeding area was1.67when there was no abamectin on the rape and mustard seedlings. The average ratio of feeding area was0.52when there was abamectin on the rape seedlings but there was no abamectin on the mustard seedlings, There was a significant difference(p<0.05). The average ratio of feeding area was74.08when there was no abamectin on the rape and broccoli seedlings. The average ratio of feeding area was4.13when there was abamectin on the rape seedlings but there was no abamectin on the broccoli seedlings. There was not a significant difference(p<0.05).