[Evidence of long distance migration of diamondback moth (DBM) Plutella xylostella: a review].

As cruciferous plants have been cultivated northwards due to climate warming, diamondback moth (DBM) Plutella xylostella is becoming a major pest in North China. The long distance migration of DBM not only induces its sudden outbreak over extensive areas, but also leads to its insecticide resistance by the spread of resistant genes in large area. To elucidate the long distance migration of DBM is of significance for early warning and decision-making in integrated pest managements. So far, the migration of DBM has not yet been systematically investigated in China. Here, we reviewed the literatures about the long distance migration of DBM at home and abroad, and summarized the related evidence: 1) DBM cannot overwinter in cold regions such as northern Japan, western Canada, and northeast China, where the DBM outbreak is presumed from elsewhere by long distance migration, 2) DBM adults are captured from seas, mountain tops, sea islands, and sky, etc., and the collection of large quantity of DBM presents the powerful direct evidence of DBM long distance migration, 3) the sudden increase of DBM in fields is consistent with the meteorological conditions such as the presence of nocturnal temperature inversion layer and the front passage, suggesting that these meteorological conditions supply suitable backgrounds for the insect migration, 4) the target insect characters identified by vertical insect looking radar is consistent with the measured DBM characters in laboratory and the trapping data from fields, confirming the long distance migration of DBM, 5) the biological characteristics and genetic variations of different DBM populations have no correlations with geographic distance, suggesting the frequent gene flows among the populations in different positions, and 6) the flight test of DBM indicates its long distance flight capacity, and the decreasing fitness of host plants is probably one of the trigger factors for the migration of DBM. Some future research directions are prospected: the construction of track model for DBM long distance migration to clarify the DBM long distance migration pathways in China; the further understanding on the physiological, biochemical, and ecological bases of DBM long distance migration; the strategies for the population insecticide resistance management based on the long distance migration of DBM.