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The Mechanism Of Fruit-Boring Weevils Of Attelabidae’ Oviposition Behavior And Their Relationship With The Host Plants

Posted on:2021-10-27Degree:MasterType:Thesis
Country:ChinaCandidate:W LiFull Text:PDF
GTID:2493306308959369Subject:Master of Engineering
Abstract/Summary:PDF Full Text Request
Insects of Attelabidae,also called as leaf-rolling weevils,have unique behaviour of oviposition that their females destroy or cut the laid-egg organs of host plants by different ways before and after oviposition.Females of their most species use the host leaves to make leaf rolls for laying egg or cut off or damage the leaves or leaf stalk or twigs before making leaf roll,but the mechanism of the such behaviour is not reported up to now.The study took the boring-fruits Rhynchites foveipennis Fairm as the research object and made the experiments that R.foveipennis was prevented from destroying the fruit stalk and Mechoris ursulus Roelofs of boring insect was prevented from cutting off branches in both the laboratory and the filed survey under the new designs and methods.The paraffin sectioning of egg chamber’callus and the related factors affecting the formation of callus were also observed.It was also studied the mechanism of the larval growth retardation of R.foveipennis.The results are the followings.(1)After preventing the R.foveipennis from damaging the pear stalk,the egg mortality was 66.4% when the female laid eggs in the living host pear fruit;while the egg mortality was only 6.0% when the female laid eggs naturally with damaging the pear stalk.Their difference was 11.1 times.After preventing the R.foveipennis from damaging the pear stalk,the larvae could not grow and develop normally.The average weight of each larva was 3.17 mg 30d after laying eggs,and the mortality was72.7%.The average weight of each larva was 74.92 mg 30 days after laying eggs,and the larval mortality was 3.6%.The difference of their larva’s weight was 23.6times.The egg mortality of M.ursulus was 82.1% after preventing M.ursulus from cutting branches when M.ursulus laid egg in nut of Q.franchetii.(2)The paraffin sections of the pear fruit tissue in the egg chamber of R.foveipennis showed that the tissue killing egg of R.foveipennis was callus.After preventing M.ursulus from cutting off branches,the eggs were dead because of the extrusion of the host callus and the callus was also formed after mechanical damage.After R.foveipennis was prevented from damaging the stalk,the contents of IPR and IP in the pear fruits obviously increased,while the IAA content did not obviously changed.The results showed that the egg-laying behaviour of R.foveipenni induced the dynamic balance between the two hormones which formed the callus of the host plant,and the such callus made the eggs dead.(3)The egg’s development of R.foveipennis were greatly affected by temperature,and the egg duration had little relationship with the water content in the simulated host fruits.At the temperature of 20-25℃,the callus grew faster than the eggs did,and so,the eggs were dead before hatching squeezed by the callus.The egg mortality of R.foveipennis was 83.6% in the Huang pear fruits on the trees and 38.6%in the Baozhu pear fruits on the trees.And the egg mortality of R.foveipennis were also different in the young stage,expansion stage and maturity stage respectively.Therefore,it was speculated that the callus formation was different in different kinds of pear species and different developmental stages.(4)After preventing the female of R.foveipennis from damaging the stem of pear fruit in the early stage,expansion stage and maturity stage of the pear fruit,the contents of JA,SA and ABA all increased obviously compared with the healthy fruit without laying eggs,and began to increase from one day to three days after laying eggs.The contents of SA decreased 5 days or 7 days after laying eggs and the content of JA after deducting its content in the expansion period also decreased.And the content of IAA was increasing;the content of PPO increased after the females laid eggs.The content of cysteine protease inhibitor(CYS-C)began to increase 3 days after laying eggs.And therefore,the experimental results also showed that the defense response of the pear fruit might be induced by multiple conduction pathways and their synergistic action,and finally produced the defense substance that hindered the larval growth and development of R.foveipennis.(5)According to the measuring results of the larval palate’s width,the larvae of R.foveipennis were divided into four instars.In the mechanical damage experiment simulating the oviposition of the female of R.foveipennis,the larvae could not complete the growth and development after they were inserted into the live pear fruit on the tree,whether they were the newly hatching or ever instars ones.But,they could gradually resume growth and development once they were transferred into the pear fruit cut off the tree.Therefore,it is speculated that the ovipositon of female of R.foveipennis or mechanical damage would induce that the pear fruits produce the defensive substances that would hinder the growth and development of the larvae.By comparing the growth and development of the larva of R.foveipennis in the pear fruits of two pear species of Baozhu pear and Huang pear on the trees,it was concluded that the defense ability of the Huang pear might be stronger than that of the Baozhu pear.
Keywords/Search Tags:Rhynchites foveipennis Fairm, pear fruits, Ovipositing behaviour, callus, mutual relationship between insects and plants, host defense
PDF Full Text Request
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