Mating Disruption of Striped Rice Stem Borer: Importance of Early Deployment of Dispensers and Impact on Airborne Pheromone Concentration

Mating disruption(MD)is an effective environmentally-friendly control method against the striped rice stem borer(RSB),Chilo suppressalis(Lepidoptera:Crambidae).In this study,the current MD dispensers release the pheromone exponentially,with higher initial release rates that decrease throughout the time.To adjust the timing of dispensers'deployment and evaluate the importance of controlling the early first or the second male flight,field trials were carried out to test the efficacy of two strategies:the early dispenser deployment prior to the first male flight(May)and the late deployment prior to the second flight(June).The early dispenser deployment was more effective in reducing plant damage inflicted by RSB when assessed at harvest.However,neither of these strategies was able to inhibit the male catches of the third flight due to the dispensers5 depletion.Attending to the airborne pheromone concentrations obtained,around 1.60 ng/m3 were capable to inhib社C.suppressalis male flight effectively.

Production of Volatile Moth Sex Pheromones in Transgenic Nicotiana benthamiana Plants

Plant-based bioproduction of insect sex pheromones has been proposed as an innovative strategy to increase the sustainability of pest control in agriculture.Here,we describe the engineering of transgenic plants producing(Z)-11-hexadecenol(Z11-16OH)and(Z)-11-hexadecenyl acetate(Z11-16OAc),two main volatile components in many Lepidoptera sex pheromone blends.We assembled multigene DNA constructs encoding the pheromone biosynthetic pathway and stably transformed them into Nicotiana benthamiana plants.The constructs contained the Amyelois transitella AtrΔ11 desaturase gene,the Helicoverpa armigera fatty acyl reductase HarFAR gene,and the Euonymus alatus diacylglycerol acetyltransferase EaDAct gene in different configurations.All the pheromone-producing plants showed dwarf phenotypes,the severity of which correlated with pheromone levels.All but one of the recovered lines produced high levels of Z11-16OH,but very low levels of Z11-16OAc,probably as a result of recurrent truncations at the level of the EaDAct gene.Only one plant line(SxPv1.2)was recovered that harboured an intact pheromone pathway and which produced moderate levels of Z11-16OAc(11.8μg g^(-1) FW)and high levels of Z11-16OH(111.4μg g^(-1)).Z11-16OAc production was accompanied in SxPv1.2 by a partial recovery of the dwarf phenotype.SxPv1.2 was used to estimate the rates of volatile pheromone release,which resulted in 8.48 ng g-1 FW per day for Z11-16OH and 9.44 ng g^(-1 )FW per day for Z11-16OAc.Our results suggest that pheromone release acts as a limiting factor in pheromone biodispenser strategies and establish a roadmap for biotechnological improvements.