Management of the Diamondback Moth and Other Crucifer Insect ...

were applied to control DBM in 1992 and 1994, thelosses of summer cabbage were 99% and 80%,respectively compared with the insecticide-treated plots(Zhao et al. 1996).In 1953, DBM was reported by Ankersmith as the firstcrop pest in the world to develop resistance to DDT inJava, Indonesia (Ankersmith 1953). The resistancedevelopment to several insecticides had been reported inthe Philipines (Barroga 1974), Australia (Altman 1988),Hawaii (Tabashnik et al. 1987), Malaysia (Syed, 1992),Japan (Hama, 1992), North America (Shelton et al.1993), Thailand (Kuwahara et al. 1995). In 1992, Chengand Tang reported the resistance of DBM to insecticidesin PR China. Up to now, because of the extensiveselection pressure and its high potential for developingresistance, DBM had developed resistance to the majortypes of insecticides, including organophosphates,organochlorines, carbamates, synthetic pyrethroids, someinsect growth regulators, and microbial insecticides suchas Bacillus thuringiensis (Liu et al. 1981; Miyata et al.1992; Tabashnik et al. 1990; Talekar and Shelton 1993).In PR China, chemical control is still the main way tomanage the DBM. The massive abuse of chemicalinsecticides was leading to the rapid development ofinsecticide resistance. Due to insecticide resistance andeventual control failure of DBM, economical productionof crucifers had become almost impossible in certainChinese areas (Liang et al. 2001; Liu et al. 2005).In the past two decades, Chinese entomologists hadcarried out more research on DBM in PR China,including occurrence, resistance, molecular geneticmechanism and IPM, etc. Some measures had beendeveloped in cultural control, chemical control, physicalcontrol and biological control, although systematicdemonstration was lacking. In order to produce betterquality brassica vegetables and canola, it is necessary tobuild and demonstrate new integrated technologiesaccording to the local conditions of different areas. In2008, a national project, the Special Fund for AgroscientificResearch in the Public Interest, supported theresearch on sustainable management of DBM. Theproject is a group effort involving 117 entomologistsfrom ten institutes or universities, including nearly allDBM experts in PR China. The group covers fivegeographic areas, viz., south, south-west, east, north andcenter. The significant progress made in the projectduring the past three years is presented here.Investigation on population dynamics infive geographic regionsPopulation dynamics of DBM in 14 locations from 10provinces in south, south-west, east, north and centerChina were investigated. The results showed that therewere more than 20 generations in south China and it wasonly 2-3 generations in north-east China. There were oneor two population peaks in different areas during springor autumn. The time of initial peak occurred duringFebruary – March in South China and May – June inNorth-East China. The spring peak was higher than theautumn one in North China, whereas the two peaks weresimilar in South China.In 2010, the Chinese DBM population was significantlylow, and it could be due to the changes in climate, naturalenemy population and cropping systems. In terms of theclimate, mean spring low temperature and summer hightemperature was one of the reasons. At the same time,the population was also controlled by a tremendousamount of rainfall. In addition, the natural enemiesincluding Diadegma semiclausum, Cantheonideafurcellata and Erigonidium graminicola) and thecropping systems including rotating rice, corn and shallotin summer were effective in managing the DBM.Current status of insecticide resistancein DBM in PR ChinaDBM field populations were monitored for theirresistance to 11 selected pesticides (Table 1) in 34locations in south, south-west, east, north and centerChina following a standard method. The results showedthat the resistance was serious in all locations. Therewere significant differences in resistance to an insecticideamong the study sites. The resistance was more seriousin south, south-west and east China than other parts. Theresistance in Danzhou (Hainan Province) was the mostserious. High resistance is correlated to the populationdifferences and over-use of insecticides. It is verydifficult to plant vegetable brassicas in south Chinaduring summer because of high resistance in DBM. So,the farmers in the north or west China prefer plantingvegetable brassicas during summer. However, it is aremarkable fact that the insecticide resistance in DBM indifferent geographical regions is gradually decreasingyear by year from 2008 to 2010, which proves that theIPM technologies demonstrated and promoted throughthe project are effective.Over-wintering and migrationSome research work was also carried out on the natureand north limit of over-wintering. The super-coolingpoint was high with the growth of larva, and the meanwas -13.72°C. The super-cooling point was lowest forthe pupa. The freezing point had the same trend as thesuper-cooling point. The research on the north limit ofhibernation in PR China showed that the north limit wasthe area from Wuhan to Zhu-ma-dian based on theinvestigation on over-wintering in 19 locations.The genetic differences among 10 geographic DBMpopulations were lower. Hence, DBM could migratefrom south to north. The adult migration and climatecondition were monitored in 19 locations. The resultsshowed that there were two models of migration, viz.,move in and move out (e.g., in Wuhan and Nanjing) andmove in and settle down (e.g., Datong and Shenyang).Simultaneously, the resistance of DBM in differentlocations was analyzed and found that it was very similarto different insecticides among Wuxue (eastern Hubeiprovince), Luoyang (western Henan province) andBeijing (northern China), which could be due tomigration.16 AVRDC - The World Vegetable Center