| The Yellow peach moth, Conogethes punctiferalis (Guenée), is an omnivorous pest insect. In recent years, the damage to corn caused by C. punctiferalis has increased in Huanghuaihai Summer Corn Region and Southwest Hilly Corn Region in China. It has become the major pest of maize in these regions, where the population and damage of C. punctiferalis were even more serious than Asian corn borer, Ostrinia furnacalis in some years and some districts. The investigation on the survival of overwintering larvae of C. punctiferalis in corn stalks and sunflower heads in field in spring in Langfang, Hebei province indicated that the overwintering survival rates of C. punctiferalis was very low, no survival larvae was observed. It was reported that the supercooling point of C. punctiferalis overwintering larvae was low. In addition, the population of C. punctiferalis was observed through radar detection. It was asummed that the C. punctiferalis might be a migratory pest insect. In this study, we examined the flight capacity of C. punctiferalis adults and the effects on adult flight capacity when the larvae developed from different host plants: corn, sorghum, and sunflower, respectively. Meanwhile, we also studied the population differentiation and genetic diversity of eleven C. punctiferalis populations from different districts in China by using Inter-Simple Sequence Repeat (ISSR) markers. The main results are as follows:1. Flight capacity of C. punctiferalis adults was not significantly different between male and female moth at first day after emergence. The flight distance of male and female is 9.12±0.28 km and 9.58±0.49 km, respectively in a 36 h duration flight. The pupal weight had no significant correlation with flight distance (|r| =0.11780.05)and flight duration(|r|=0.078850.05).2. Temperature and humidity affected the flight capacity of C. punctiferalis adults. Adults could fly normally from 20℃to 32℃with the strongest at 28℃. Higher or lower than 28℃, the flight capacity would decline. Adult flight capacity increased with the increase of humidity. The flight capacity was the strongest at the 80% RH. Supplementary nutrition for C. punctiferalis adult had no significant effect on the flight capacity of the adult. However, mating behavior could significantly affect the flight capacity of C. punctiferalis. The mean flight distance, mean flight duration and mean flight speed of unmated months was significantly higher than that the mated, respectively. The distance, duration and speed of fight were significant different between months developed from overwintering and nonoverwintering larvae. The flight distance and flight duration of the months developed from overwintering larvae were higher, but the fight speed was lower than that from nonoverwintering ones .3. The C. punctiferalis moth has a strong ability to fly. The strongest flight ages of C. punctiferalis was 3-5 days after emergence. The flight capacity of C. punctiferalis collected from corn and sunflower reach to the highest point at the 3rd day after emergence, and the flight distances was 21.14km and 22.86km, respectively, in a 24 h duration. The flight capacity of C. punctiferalis collected from sorghum was strongest at the 5th days after ermergence, the flight distance is 21.74 km. No significant was observed in mean fight distance of C. punctiferalis adults at different ages among the months from the three host plants, except for the 7 days after emergence. However, the flight capacity of C. punctiferalis at different ages was significantly different among the three host plants in flight duration and flight speed. It indicated that feeding on different host plants in larval stage had affected the flight capacity of adult subsequently.4. Genetic diversity among 11 geographic populations of C. punctiferalis collected from 6 provinces in China was investigated using Inter-Simple Sequence Repeat (ISSR) markers in this study. Six of the 34 used primers were chosen for our ISSR polymorphic analysis. The results showed that 209 bands were polymorphic, making up 99.05% of the total 211 amplified bands. The genetic distances between different C. punctiferalis populations were 0.0059-0.0237; the Nei`s index, Shannon information index, coefficent of genetic (gene) differentiation among populations (Gst) was 0.1750, 0.2966, 0.053, respectively, and the estimated value of gene flow from Gst was 8.8724. Analysis of Nei`s genetic diversity showed that there was a low level of population genetic structure with a considerable frequency of gene flow.This study provide theoretical basis for further study on dispersal behavior, population dynamics and genetic diversity of C. punctiferalis. It contributes to explore the possibility of migration in C. punctiferalis. It has also suppled the fundamental data for making the effective strategy of C. punctiferalis managemnet in China. |
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