Effect of temperatures and diets on the life cycle of Ephestia elutella

Ephestia elutella (Hübner) (Lepidoptera: Pyralidae), an omnivorous pest with a wide range of hosts, is responsible for the damage and loss of many stored commodities. However, the parasitoid wasp Habrobracon hebetor (Say) (Hymenoptera: Braconidae) utilizes 5th instar E. elutella larvae to breed. In order to support the large-scale production of E. elutella for research and parasitoid rearing, we explored the effects of diet (artificial diet and tobacco) on the mortality, developmental duration, adult longevity, fecundity, and population parameters of E. elutella reared at 19, 22, 25, 28, and 31˚C using age-stage, two-sex life tables. Increasing the temperature from 19 to 31˚C significantly affected the stage-specific mortality, reproductive parameters, and population parameters of E. elutella. Specifically, both developmental duration and adult longevity decreased with increasing temperature. For both diets, pre-adult mortality was lowest at 25˚C, but was lower overall in populations fed an artificial diet. The developmental duration, adult longevity, and mean generation time (T) were significantly lower in populations fed an artificial diet, whereas the intrinsic rate of increase (r) and finite rate of increase (λ) were significantly lower in populations fed tobacco leaves. Temperature appears to have a significant effect on the development and reproduction of E. elutella, and a combination of 25˚C and artificial diet may be the most conducive to large-scale breeding. This study provides a theoretical basis for the mass rearing of E. elutella to support pest control applications in tobacco warehouses.

Methods
 Age-stage, two-sex life tables

烟草粉螟（Ephestia elutella, Hübner）（鳞翅目（Lepidoptera）螟蛾科（Pyralidae））是一种广食性寄主害虫，可造成多种储藏物的损害与产量损失。而寄生性天敌麦蛾茧蜂（Habrobracon hebetor, Say）（膜翅目（Hymenoptera）茧蜂科（Braconidae））则以烟草粉螟5龄幼虫作为寄主完成繁育。为支撑烟草粉螟的规模化繁育以满足科研及寄生蜂饲养需求，本研究采用年龄-阶段两性生命表（age-stage, two-sex life table）方法，探究了19、22、25、28、31℃饲养条件下，人工饲料与烟草叶片两种饲料对烟草粉螟死亡率、发育历期、成虫寿命、繁殖力及种群参数的影响。将饲养温度从19℃提升至31℃，会显著影响烟草粉螟的阶段特异性死亡率、繁殖参数及种群参数。具体而言，发育历期与成虫寿命均随温度升高而缩短。两种饲料处理下，烟草粉螟的未成熟期死亡率均在25℃时最低，但整体而言取食人工饲料的种群未成熟期死亡率更低。取食人工饲料的种群，其发育历期、成虫寿命以及平均世代时间（mean generation time, T）均显著更短；而取食烟草叶片的种群，其内禀增长率（intrinsic rate of increase, r）与周限增长率（finite rate of increase, λ）则显著更低。温度对烟草粉螟的生长发育与繁殖具有显著影响，25℃配合人工饲料的饲养条件或许最有利于其规模化繁育。本研究可为烟草仓库害虫防控所需的烟草粉螟大规模繁育提供理论依据。方法 年龄-阶段两性生命表