A Preliminary Investigation On Resources Of Leaf-Rolling Weevils In Yucheng District,Ya'an,and A Study On Reproductive Strategies Of Apoderus Dimidiatus(Coteoptera:Attelabidae)

Attelabidae belong to Coleoptera,Insecta,known as leaf-rolling weevils,are famous for their special behavior of leaf-rolling,and widely distributed in China.However,the relevant research is rarely.In 2018,the resources of leaf-rolling weevils and their host-plants were investigated,and a total of 240 leaf-rolling weevil samples were collected which belong to 14 species and developed on 19 plants.Most of them are specialists,however,Apoderus dimidiatus developed on seven plants belonging to three orders.Ap.dimidiatus with broad host-plants is a suitable species for researching insects‘ reproductive strategies.The number dynamics and the distribution between plants of Ap.dimidiatus population in Huanglong Village where distributed with Ro.multiflora and Ru.Ichangensis and in Liuliang Village where distributed with Co.nepalensis and L.indica were recorded firstly.The proportion of suitable leaves on host-plants,the shape,water content and nutritional contents of leaves,egg quantity within each leaf-roll,and weight and feeding preference of new adults were all measured to research the reproductive strategies of Ap.dimidiatus,.The results illustrate that: 1)the breeding season of Ap.dimidiatus was two months longer in Liuliang than Huanglong,had one peak in April and October respectively in Liuliang,and had one peak in Huanglong,which may relate to higher daily temperature in Liuliang;2)extremely low proportion of suitable leaves on host-plant directly restrict the oviposition selection,when it higher than a certain value,the selection wouldn‘t be restricted;3)mother‘s ovipostion selection and the genetic relationship between host-plants don‘t decide offspring‘s feeding selection;4)there was no difference in the weight of new adults developed on different host-plants;5)that females laid two or three eggs separately in large leaf-rolls probably avoid cannibalism and use resources fully.Parasitic species,parasitic rate and survival rate of A.dimidiatus offspring on four host-plants were recorded.The results show that A.dimidiatus offspring parasitized by seven parasitic wasps,including three belong to trichogrammae,three belong to Pteromalidae and one belong to Braconidae,attacking the offspring of Ap.dimidiatus occurred majorly from May to September.Most of them were oophagous trichogrammae attacking eggs of Ap.dimidiatus,and the rest attacked pupa stage.The parasitic wasp communities of offspring on four host-plants were different,and both Ro.Multiflora and Co.nepalensis had a special parasitic wasp.The parasitic rate was higher in Huanglong than Liuliang,higher on Ro.multiflora than Ru.ichangensis,and higher on Co.nepalensis than L.indica.Offspring‘s survival rate was strongly negative with parasitic rate illustrating that parasitism is the major factor causing death.Combining all results,we could infer that: females lay two or three eggs in large leaf-rolls for saving energy;in Huanglong,females prefer to constructe leaf-rolls using R.multiflora leaves with higher nutritional contents,however,those leaf-rolls are strongly attacked by parasitic wasps,and females constructe some leaf-rolls(no more than 20%)on R.ichangensis could slightly cut down the parasitic rate of the population;in Liuliang,reproductive peaks of Ap.dimidiatus miss the reproductive peak of parasitic wasps,which cut down the parasitic rate effectively but let the last offspring in a lower temperature environment.