Composition Analysis And Field Application Of Volatiles Attracting Harmonia Axyridis In Vitex Negundo

Herbivore-induced plant volatiles are a key component of plant-phytophagous insect-natural enemy insect communication.In fact,plants attract natural enemies to respond to herbivore feeding by releasing pest-induced plant volatiles.In organic production management,biological control technology has begun to use pest-induced plant volatiles as a key component of chemical pheromones.Using chemical pheromones to regulate natural enemy insects is also one of the important measures for green pest control.In this dissertation,functional plants with high conservation ability to predatory ladybugs were screened,and the V.negundo volatile components attracting H.axyridis were analyzed,and the field application effect of V.negundo active volatiles was studied.The main conclusions are as follows.In order to clarify the number of predatory ladybird populations on functional plants.The dynamics of predatory ladybirds were monitored by setting up functional plant plots in the field,the survey found that among the 25 functional plants,the average number of predatory ladybirds on a total of 15 functional plants,such as Crepidiastrum sonchifolium was less than 5 heads/area.The number of predatory ladybirds on the top 10 functional plants,including Lagopsis supine,Cosmos bipinnatus,Anemarrhena asphodeloides,Salvia miltiorrhiza,Capsicum frutescens,Vigna unguiculata,Artemisia sieversiana,Zea mays,Helianthus annuus and V.negundo was 7,41.67,9,7.33,52.67,8.33,50,23.67,28,and 62 heads/area,respectively.The predatory ladybirds migrated back and forth between the orchard and the surrounding functional plants,and the V.negundo played a role in conserving natural enemies in the early stage.It can provide an initial source of natural enemies for orchards.In order to clarify the information substance that causes the behavioral preference of H.axyridis,an olfactory behavior selection experiment was conducted using V.negundo.It was found that H.axyridis showed significant olfactory preference for V.negundo after damage by A.gossypii.The volatiles of V.negundo were analyzed by GC-MS,which showed that the fold change of methyl salicylate(Me SA)had the largest among the substances released after damage by A.gossypii and the five volatile compounds were significantly up-regulated,and the five substances in the terpenoid biosynthesis pathway were significantly down-regulated.The candidate active compounds mediated by A.gossypii that could attract H.axyridis were screened,and the olfactory behavior of the candidate active compounds to H.axyridis was tested,olfactory behavioral responses showed that H.axyridis had significant preference for Me SA,sclareol,eucalyptol,nonanal and terpineol.In order to clarify the field application effect of active substances(Me SA).The population dynamics of predatory ladybirds and Aphis citricola were investigated,and the slow-release rate of Me SA was detected.The effects of Me SA on the spatial distribution characteristics of predatory ladybirds and A.citricola were analyzed,it was found that the peak period of A.citricola in apple orchards in Beijing was from the end of May to mid-June.The number of predatory ladybirds in the treatment area was significantly higher than that in the chemical control area,and the number of A.citricola was significantly reduced by hanging Me SA PE slow-release rubber one week before the peak period.The results of spatial distribution showed that A.citricola showed the characteristics of marginal aggregation distribution in each apple orchard.In addition,the release rate of Me SA PE slow-release rubber was about 0.68 g/week,which could last for more than 4 weeks in the orchard,the highest density of A.citricola appeared on the edge of the park treated with Me SA PE rubber.In summary,through the population dynamics of predatory ladybugs,it was found that V.negundo can be used as a habitat plant for reserving natural enemy insects in the early stage,and it can significantly attract H.axyridis after being damaged by A.gossypii.Me SA,sclareol,eucalyptol,nonanal and terpineol showed significant attraction to H.axyridis.The application of Me SA in the field can reduce the occurrence of A.citricola,increase the occurrence of predatory ladybirds,regulate the distribution pattern of A.citricola,and prevent its spread to the park.It provides an important basis for functional plants in the integrated pest control system and chemical pheromones in natural enemy attraction technology,it also provides an evaluation method for visual analysis of orchard pests.