Effects of nitrogen fertilization on reproduction and offspring sex ratio in Megalurothrips usitatus(Bagrall)(Thysanoptera:Thripidae)
In order to evaluate the influences of nitrogen fertilization on reproduction and sex ratio of Megalurothrips usitatus(Bagrall),an economically important pest of legumes,the 1-day-old mated females were provided daily with leaf disks cut from the first leaves of potted cowpea at the age of 13 to 15 days,which were fertilized as a single pre-plant application with three different levels of urea at rates of 0,160,and 320 N kg·hm-2,respectively.After being checked the number of eggs,each leaf disk was transferred into a glass tube containing a section of young bean pod of cowpea,which was harvested from the field plants.Oviposition days of the focal females were recorded,and their offspring adult were sexed and counted.Sex ratios of offspring were calculated as proportion of males.The results showed that the females reared on leaf disks from plants fertilized with high N had significantly prolonged survival duration and oviposition duration,and shortened pre-oviposition period,and significantly greater oviposition rate and daily oviposition rate,compared to low N and medium N treatments.Offspring sex ratios for low N,medium N and high N treatments were 0.70,0.59,and 0.45,respectively,which were significantly different among each other.The number of offspring females produced by the females increased as N application rate increased.The number of offspring adults for high N treatment was significantly higher than those for low N and medium N treatments.N application level had no effect on immature survival of the offspring.In conclusion,nitrogen fertilization impacts on development,reproduction,and sex ratio of M.usitatus.Nitrogen overfertilization increases offspring production of this thrips,with a female-biased sex ratio.
NETL
NSTL
万方数据
维普
