| Accurate information on the age of wild animals is of great value to many fields.Similarly,for small insects,the determination of their exact age is also of great value in many fields,such as pest control,selection of insect spouses,mating behavior and evolution,population age structure and occurrence time dynamics,insect behavior and reproduction.In pest detection and early warning,it is not necessary to investigate the development progress of pests,and the occurrence period of pests can be accurately predicted by the method of insect age classification.The age structure of the population can reflect the effect of pest control and control methods,and it is an important factor to determine the reproductive potential of the population.As a population identification marker,the age structure of the population can be used to study the migration behavior of migratory insects.The determination of insect age is helpful to detect population activity and establish mathematical model of population structure,so as to predict insects effectively.The determination of insect age is very important to insect research.In this paper,the lipofuscin and pteridine were extracted and the internal reproductive organs were dissected to study the lipofuscin and pteridine concentration and the morphologies of the ovaries and testes in 1-6-day-old moths and to carry out a study on the determination of day age of these migratory pests,so as to determine the adult age of rice leaf roller and provide theoretical basis for the prediction and forecast.The following results were obtained:1.Lipofuscin and pteridine concentration of female and male adults of C.medinali(1)LipofuscinLipofuscin accumulated in head,thorax and abdomen,but mainly accumulated in the head.There were no significant differences in lipofuscin concentration in the head,thorax and abdomen of adults of Cnaphalocrocis medinalis with different sex and age.So lipofuscin can not be used as an index to judge the adult age of Cnaphalocrocis medinalis.(2)PteridineThere was no significant correlation between the content of pteridine in adult head and sex and age,and there was no interaction between sex and age.Therefore,pteridine can not be used as an index to determine the adult age of rice leaf roller.2.The internal reproductive organs of female adults of C.medinali(1)Reproductive organs of female mothsThe ovarian structure of 1-6-day old female moths was dissected and the ovarioles length,basal(first three)eggs of ovarioles length,yolk deposition and copulatory pouch length in the reproductive system were studied.The results showed that the ovarioles length increased with the increase of age and reached the maximum at 3 days of age and then decreased.Before 3 days of age,The length of ovariole of the females had significant differences between ages and the ovarioles length increased with the increase of age.After 3 days of age,the ovarioles length decreased with the increase of age.Based on the results that there were no significant differences in ovarioles length at 3,4 and 5 days,the basal(first three)eggs of ovarioles of 3-5-day old females were studied in order to find the difference between 3-5-day old females.The results showed that the basal eggs of ovarioles length were increased first and then decreased.The variation of total ovarian deposition length of female moths was basically consistent with that of ovarioles length,that is,the deposition length increases first and then decreases with the increase of age,except for 1-day and 2-day-old(no deposition).The proportion of female moth deposition to ovarioles length remained basically unchanged after 2 days of age.There was no significant difference in the copulatory pouch length,except for 2 days of age.(2)Age estimation of female mothsAccording to the length of ovarioles length and ovarian grade,the estimated age of female moths at low age can be inferred,The estimated age and chronological age had little error,the analysis of age estimation determined by the length of ovarioles showed that the mean errors of estimated age was 10.56 d in 1 day-old females and ±0.47 d in 2 day-old.But for the older female moths,the age range can only be estimated roughly.3.The internal reproductive organs of male adults of Cnaphalocrocis medinalis(1)The size of testes of male Cnaphalocrocis medinalisThe size of testes of 1-6-day old male moths were studied.The results showed that with the increase of age,the size of testes decreased gradually,and the semi-major and semi-minor axis length of testes decreased.The effects of body length,weight and mating on testis size were studied.The results showed that mating had no significant effect on the size of testis,while the length and weight of male moth had the greatest effect,but the effect was limited.Age is the main factor affecting the size of testes.(2)Age estimation of male mothsThe mean errors of estimated age determined by the semi-major axis length of testes was ± 1.28d in 1 day-old males,± 1.48 d in 2 day-old,± 1.43 d in 3 day-old,± 1.32 d in 4 day-old,±1.53 d in 5 day-old and ±1.29 d in 6 day-old.The mean errors of estimated age determined by the semi-minor axis length of testes was ±1.15 d in 1 day-old males,± 1.04 d in 2 day-old,±0.97 in 3 day-old,± 1.12 d in 4 day-old,± 1.46 d in 5 day-old and ± 1.21 d in 6 day-old.Compared with the chronological age,the estimated age is generally lower.It is concluded that lipofuscin and pteridine can not accurately reflect the age of C.medinali.Ovarioles of female moths and testes of male moths are used as indicators of age,although there are some shortcomings,but their morphology are stable and related to the adult age and have great potential applications in determination of adult age of C.medinali. |
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