Research On The Relationships Between Oviposition Preference And Offspring Performance Of Ostrinia Furnacalis

The relationships between oviposition preference and offspring performance of herbivorous insects are central for understanding the co-evolution between them and their host plants.According to the "preference-performance" hypothesis(PPH),insects lay eggs on the host with the best-performing offspring.However,this phenomenon is often influenced by many biotic and abiotic factors.Most previous studies have mainly considered the mediated effects of insect traits on oviposition preference and offspring performance,but the effects of other biotic and abiotic factors are understood poorly.In this study,we examined the responses of oviposition selection and offspring fitness of Ostrinia furnacalis,an important insect pest of corn,for host plants Zea mays under different biotic and abiotic treatments(endophytic entompathogenic fungi,water stress,the interaction between water stress and nitrogen fertilizer reduction),and further determine the relationships between oviposition preference and offspring performance.Under controlled conditions,endophytic entompathogenic fungi treatments(Control,A8 Beauveria bassiana,D1-5 and A3),water stressed treatments(well-watered,moderately watered-stressed and severely watered-stressed),and the interaction between water stress and nitrogen fertilizer reduction(suitable water and suitable fertilization,suitable water and low fertilization,low water and suitable fertilization,low water and low fertilization)were set up,and the oviposition selection(number of egg masses and eggs)of O.furnacalis for maize plants under different treatments were tested,and the number of larvae,pupae and adults,food consumption,and weight of larvae and pupae were studied by feeding trial.The underlying mechanism of the effects changed physical characteristics of maize plants(plant height,leaf length,leaf width and leaf area)and chemical properties(leaf water content,N content,free amino acid content,C content and soluble sugar content)under different treatments on oviposition selection and offspring fitness were identified.The relationships between the oviposition preference and offspring performance of O.furnacalis were further discussed.The main conclusions of this study were as follows:1.The number of eggs laid by O.furnacalis on the maize plants colonized by A3 treatment was higher than that of other B.bassiana treatments,but the survival number/rate,the number of pupae and the number of eclosion/rate after feeding on the preferred maize plants significantly decreased,as well as the weight of larvae and pupae.Reduced leaf length and leaf area of maize plants colonized by A3 treatment was one of the explained factors for oviposition responses of O.furnacalis.Decreased N content in maize plants resulted in lower performance of O.furnacalis.These results indicated that the oviposition on the maize plants colonized by B.bassiana is not beneficial to the growth and development of the larval.2.Insect females preferred to lay eggs on well-watered maize plants,and the number of larval survival/rate,pupal number/rate and adult number were higher after feeding on the host plants that prefer to lay eggs.Such oviposition preference was caused by the increase in physical characteristics and nutrients(leaf water content and C content)of maize plants under well-watered treatment.In addition,the change in water content and C content in maize leaves under well-watered treatment had a positive effect on O.furnacalis offspring.Thus,the oviposition preference of O.furnacalis adults can enhance the growth and development of their offspring under well-watered conditions.3.O.furnacalis females preferred to ovipsit on maize plants in the treatments of suitable water and low fertilization,that is,the number of egg masses and eggs was significantly higher than that of other treatments.When the larvae fed on maize under suitable fertilization treatments(including suitable water and suitable fertilization,low water and suitable fertilization),larvae,pupa and adults survive better,larvae and pupae developed faster,the larval weight and food intake increased significantly.Changed height,leaf length,leaf water content and C content of maize under suitable water and low fertilization treatments was closely related to oviposition preference.Significant increase in N content and free amino acids of maize plants could lead to better growth and development of O.furnacalis.The finding demonstrates there is no relationship between oviposition preference and offspring fitness under the interactive treatments of stressed water and reduced nitrogen fertilizer.In summary,the responses of the oviposition preference and offspring performance of O.furnacalis,and their relationships are mediated by B.bassiana,water stress,the interaction between stressed water and reduced nitrogen fertilizer,with showing different respsonses under different treatments.Therefore,the relationship between oviposition selection and offspring performance of insect herbivores is complex,and biotic and abiotic context-dependent.This study is important for understanding "preference-performance" hypothesis,and further provides theoretical basis for predicting population dynamic of O.furnacalis,and guides effective control for O.furnacalis under B.bassiana,water stress,the interaction between stressed water and reduced nitrogen fertilizer.