The Biology And Behavior Mechanism Of The Rapid Development Of Chlorantraniliprole Resistance In Plutella Xylostella (L.)

The diamondback moth, Plutella xylostella (L.), is an important pest of cruciferous crops. With fast breeding and strong adaptability, it has become one of the most serious resistant pest, which is greatly difficulty to be control. Chlorantraniliprole is a new insecticide that has ryanodine receptor as the target, which is good for controlling diamondback moth. However, after using the pesticide for 2-3 years, P. xylostella has produced up to 640-2000 fold resistance in southern China. The resistance development of this pesticide was faster than many commonly used pesticides. Meanwhile, P. xylostella also appeared a similar phenomenon in many parts of the world. For the rapid development resistance of diamondback moth to the chlorantraniliprole, current researches mainly focused on enhancing of the detoxification capacity and target site mutations, and biological and behavior changes in pest resistance formation also play a crucial role, then are the biology and behavior changes the mechanism of rapid development of chlorantraniliprole resistance in P. xylostella? There is no answer on this issue in China and abroad, so this paper studied and analyzed the biological and behavioral mechanism of the rapid development of resistance in P. xylostella with a laboratory strain whose lethal concentration of chlorantraniliprole is 0.26 mg/L as control. Our work aimed to provide more comprehensive evidence for in-depth understanding the mechanism of diamondback moth to rapid development of chlorantraniliprole resistance. The main results are summarized as following:(1) Compared to the LAB strain, the larvae and mean length of generation were longer than that of HR strain. The innate capacity for increase, the finite rate of increase, and the net reproductive rate of LAB strain were 0.23,1.26 and 44.98, respectively. They were all significantly bigger than that of HR strain, with the value being 0.18,1.19 and 34.55, respectively. But it was not conducive to reproduce faster because of the longer mean length of generation. The results showed that the population growth ability of LAB strain was stronger than that of HR strain. The female survival time of HR strain was shorter, but spawning time was longer, and fecundity was more.(2)There was significant difference between the choice times of HR female and LAB female for LAB male. The choice times of HR female was larger than LAB female when HR male chose female, which was no significantly different. That showed the mating choice between LAB and HR was not random, and there was a certain choice preference.(3) The resistant strains preferred to lay eggs on the middle underside of the leaves of cabbages and laid more eggs than the LAB strain on leaves L1-L5. Resistant strains laid a greater proportion of eggs on lower and higher leaves than the LAB strain, but there was no significant difference in the proportions of eggs laid by the different strains on growing points (GP), stem (S) and petioles (P).(4) Most mating activity in all three strains took place between 00:00-06:00, but the timing of the second mating peak differed between strains. The LAB (29.40%) and MR strains (25.91%) occurred between 18:00-24:00, whereas that of the HR strain (28.67%) occurred from 12:00 to 18:00. (3) The percentages of eggs laid in the daytime by the LAB, MR and HR strains were 39.49%,37.57% and 42.67%, respectively, but the proportion of eggs laid in the daytime by the HR-strain was significantly higher. All three strains were similar in the timing of oviposition; oviposition periods could be ranked in descending order of egg abundance from, 00:00-06:00,12:00-18:00,18:00-24:00 to 06:00-12:00.The reproductive contribution of the resistant strain is higher. The resistant strain of males was preference to female strains. Resistant strains prefer to lay their eggs on the mid-underside of lower cabbage leaves. There were some differences in the timing of mating and oviposition between the resistant and LAB strains. Furthermore, the peak mating periods of the HR and LAB strain were partly staggered. These behavioral differences facilitate the vertical transmission of resistance genes, but further research is required to determine what extent they affect the speed of developing resistance to chlorantraniliprole in P. xylostella.