Study On The Ontogenesis, Oviposition Behavior And Host Selectivity Of Scleroderma Guani Xiao Et Wu

Scleroderma guani Xiao et Wu was one of the most effective exoparasitic natural enemyinsects against the longhorn beetles and other borer pests. It has been widely used in the controlof the borer pests of forests, gardens, cash crops and medicinal plants. It will play an importantrole in the protection of forest resources and the sustainable development of forestry. Theontogenesis, spawning behavior and host selection mechanism of the S. guani were studied inthis paper. The main conslusions were as follows:1. Culture in vitro method of eggs was put forward in this paper, which reduced thedifficulty of a large collection of different developmental stage eggs. This method provided asimple and practical cultivation technique for indepth study of individual development andphysiology and biochemistry.2. In embryonic developmental researches, the author screened the Schiff's reagent-pyridine staining method. This method is suitable for embryo dyeing production observation.The embryonic developmental period of Scleroderma guani Xiao et Wu was divided into fourstages on the basis of morphological feature.It included the early development stage, the germband elongating and organic differentiation stage, the dorsal closure stage, and the embryomaturation stage.3. The author measured the stylet length and width of larvae. According to frequencyhistograms, Dyar's law, Crosby's growth law and regression analysis, the instar nummer of thelarvae could be divided into4instars. The dividing result was verified by the actual moltingobservation. On the basis of above researches, the larval stylet morphology was studied toevaluate its application in instar dividing. The result showed that the method of applicationstylet morphology to divide the instar was more simple and accurate than that of conventionalobservation molting.4. The ovipositional preparatory behaviors of the Scleroderma guani Xiao et Wu wascomposed of assembing, stinging, feeding, resting and cleaning stage. The female spendeddifferent physical and time on different behavioral stages. The ovipositional preparatory periodof the female under the normal circadian rhythm culture is shortened by about0.65days thanthat under the completely dark conditions. There was a closely relationship between theovipositional preparatory time and stinging the host time.5. The Scleroderma guani Xiao et Wu prefered to oviposit on the abdominal back ofMonochamus alternatus larvae, and most of the eggs distributed in the3-7abdominal segment.There is an approximately positive relationship between the area of Tenebria molitor pupaabdominal segment and the number of eggs. The total number of eggs of the T. molitor pupasurface was increased day by day. The number of eggs reached the maximum in the third day ofoviposition period. On the surface of T. molitor larvae, eggs of S. guani mainly distributed in theabdominal segment, which accounted for87.23%of the total number of eggs. The number ofeggs reached the maximum in the second or third day of oviposition period. Most of the eggswere fed gradually by the female, and seldom eggs could complete their development.6. In Micromelalopha troglodyta larvae and pupa, Lymantria umbrifera larvae and pupa,low instar larvae of Conogethes punctiferalis and Polychrosis cunninhamiacola, Bombyx morilarvae, Apocheima cinerarius larvae, Noctuidae pupa, Cnidocampa flavescens larvae, Latoiaconsocia larvae and Thosea sinensis larvae, Scleroderma guani Xiao et Wu did not exhibit parasitic behavior. S. guan could completed oviposition in Pyrophorinae larvae, Tenebria molitorlarvae, Dioryctria rubella larvae, Monochamus alternatus pupa, and Bombyx mori pupa. Theoviposition behavior was different among the host species. Among them, Pyrophorinae sp.larvae body was flat. This form was beneficial to eggs distribution in the body surface. Moreover,Pyrophorinae sp. larvae had a high successful parasitism rate, so it was considered to be an idealalternative host.7.3rdto5thinstar larvae of Monochamus alternatus as host were more suitable than theyoung period larvae. Compared with M. alternatus larvae,0h and4h pupae of Tenebria molitorbreeded less average single pipe out of offsprings, and other three evaluation indexs includingoffspring average body weight (per thousand) and length, sex ratio (female/male) were notfounded significant difference.The breeding results of T. molitor larvae with different bodylength were low in all evaluation indexs.It showed that T. molitor larvae was not suitable asartificial propagation host.8. The author measured the nutrients of commonly used hosts. In addition to the moisturecontent, the protein, total sugar and fat content were found differences between the various hosts.There were liner correlations between evaluation indexs of breeding and nutrients content, bodyweight of hosts respectively. Morever, the fat and sugar content, the fat content and the sugarcontent were also of a linear relationship. There was obviously linear relationship between thetotal fecundity per host and the sugar content. The parasitic rate, offspring average body weight(per thousand) and length, sex ratio (female/male) were not founded the linear relationships withnutrients.9. Along with the parasitic time progresses, the content of protein, trehalose, glycogen andthe body weight of Monochamus alternatus larvae continued declines at various ranges.Reducing sugar content at various parasitic stages increased at different levels. The difference ofthese indexs between the control and the treatment were obviously.