| A tobacco budworm,Spodoptera litura(Fabricius)(Lepidoptera: Noctuidae),is one of the major worldwide agriculture pests that attacks as many as 109 families and 389 species(varieties)and has a strong adaptive and reproductive capacity.The moths are mainly distributed in Northeast Asia,Southeast Asia,South Asia,South Pacific,America,Africa and other places,there are serious harm in North Africa and the Mediterranean region,tropical and subtropical regions of Asia,Southwest of Japan.In China,S.litura is widely distributed in the agricultural areas,such as the middle and lower reaches of the Yangtze river basin and eastern coastal provinces such as Jiangxi Province,Hubei Province,Zhejiang Province,Shanghai Municipality and other places..In the field of crop cultivation,the moths mainly harm cotton,tobacco,sweet potato and peanut and so on,which caused severe damage for agricultural production by larvae feeding on leaves,buds,flowers and fruits.This study systematically examined reproductive of S.litura by three aspects,the mating behavior and rhythm,mating capacity and sexual selection indoors in climate chamber.The main contents and conclusions were summarized as follows:1 Diurnal activity rhythm and time budgets of adult behavior of Spodoptera lituraIn order to investigate the behavior rhythm of S.litura adult,which paired according to sex ratio 1:1 were continuously observed for six days every 30 min indoors in climate chamber.Adult behaviors were taken into five types,such as moving,resting,mating,supplementary nutrition,oviposition behaviors.Mating behavior mainly appeared in the first and second day.Adult activity behaviors(moving,mating,supplementary nutrition,oviposition)with age rising firstly and then lowered,the third day reached a peak.Behavior budget accounting for most was resting,least was mating behavior.Female and male behaviors in diurnal time budget had a significant difference(P<0.01).The moth mainly rested during the day and activities are frequent at night,Light and dark activities showed an extremely significant difference with the Mann-Whitney U test(P<0.01).All adult activities in each stage of every day were significantly difference with Kruskal Wallis H test,(P<0.01).Activities also had significant difference except for moving,oviposition behavior of female and supplementary nutrition of male among fore-night,midnight and hind-night(P<0.01).Moving,resting,mating,supplementary nutrition,oviposition behaviors of S.litura were affected by adult age and behavior rhythm is obvious.2 Diurnal rhythm of adult reproductive behavior of Spodoptera litura feeding different hostsDiurnal rhythms of adult emergence,mating and ovulating between tobacco population and cabbage population were carefully observed and researched by feeding for three generations indoors in order to find out the differences of behavior rhythm of S.litura adults among different host plants.The results showed that diurnal rhythm of two host populations were different.Female adults of tobacco population had two emergence peaks which appeared two hours before lights out and one hour after lights out,while males had only a peak which appeared two hour after lights out.Both male and female adults of cabbage population had two emergence peaks,the main peak appeared one hour before and after lights out and subordinate peak appeared between four and five hours after lights out.Mating and ovulating behaviors of both populations appeared at night.Both populations had two mating peaks,the first peak of tobacco population appeared two hours after lights out,while the cabbage population appeared five hours after lights out,the second appeared similarly,at two hours before switches on.Two populations had only one ovulating peak,which was four hours after lights out for the tobacco population,while was five hours after lights out for cabbage population.The lifetime mating duration of the tobacco population and cabbage population were 54.78±3.09 min and 60±2.58 min respectively,and they were not significantly.Mating numbers of tobacco population were from one to three,but cabbage population was only one.The results indicated that host plants affected the reproductive diurnal rhythm of S.litura.3 Sexual selection behaviors of Spodoptera litura adultsSignificant effect has been showed on the sexual selection of S.litura among adult weight,adult day age,mating experience and morphological characteristics.Females whose weights are heavy,prefer to choose heavy male,while lighter male prefer larger female.Males select just 1-old-day females,not to choose 3-and 5-old-day females,while females would rather choose 3-,5-day males.The males which have mating preference would prefer unmated females,whereas unmated females give preference to mated males.The moth females prefer to choose males whose body length is longer,wings are wider,body length is longer,the distance compound eye is small and relatively long feelers males,while morphological characteristics of S.litura females play an unimportant role in male choice.4 Mating capacity of Spodoptera litura adultsMating capacity of S.litura was studied in the laboratory,the results indicated that male mating rate significantly decreased,adult life gradually shortened,the female oviposition quantity drops rapidly after the first rise slowly with the male and female ratio from 1:1 to 1:5,As male and female ratio ranged from 1:1 to 5:1,mating numbers of females decreased significantly,the statistical analysis showed that mating numbers of 1:1 treatment group showed significantly higher than other treatment(P < 0.01),while the mated number of males was not significant(n = 3,P = 0.303),but their mating numbers increased after the first decreases,also have an impact on shortened lifespan,female oviposition numbers significantly reduced(P < 0.01).After delaying mating,mating percentage and fecundity of S.litura reduced significantly.Longevity of adults extended obviously.Their mating duration overall increased,but hatching rate influenced by delaying mating at the same time was not significant.The influence on the female mating duration,oviposition period and fecundity by female-multiple mating showed significant differences(P < 0.05).Along with the increase in number of mating,mating duration decreased,oviposition period extended,fecundity increased obviously,but the effect on hatching rate and female longevity was not obvious. |
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