Efficacy of an esfenvalerate plus methoprene aerosol for the control of eggs and fifth instars of Plodia interpunctella (Lepidoptera: Pyralidae)

Abstract  Aerosol insecticides may provide an alternative to fumigants for control of the Indianmeal moth, Plodia interpunctella (Hübner), the Indianmeal moth, a major insect pest of stored processed food. In this study, eggs and larvae (5th instars) of P . interpunctella were exposed to aerosol applications of the pyrethroid esfenvalerate and insect growth regulator methoprene, alone and in combination, in open and obstructed positions inside small sheds. When larvae were exposed to methoprene alone, adult emergence from those exposed larvae was 7.1%± 1.5%. In contrast, adult emergence was 92.5%± 3.5% when larvae were exposed to esfenvalerate alone. When eggs were exposed to methoprene, adult emergence of those exposed eggs was approximately 75%; however, when eggs were exposed to esfenvalerate, adult emergence was approximately 35%. In the combination treatment of methoprene plus esfenvalerate at their respective label rates, adult emergence following larval exposure was 0.91%± 0.61% compared to 16.3%± 9.6% when eggs were exposed. Based on our results, methoprene alone is highly effective in reducing adult emergence after larval exposure. However, it is not as effective on eggs as esfenvalerate. A combination treatment of esfenvalerate plus methoprene could be used to control eggs and the wandering-phase larval stages of P . interpunctella . An economic risk analysis also supports a strategy of combining methoprene and esfenvalerate.     

明亮熊蜂繁育室内印度谷斑螟的形态特征与生物学特性

明亮熊蜂Bombus lucorum L.是一种重要的温室果菜传粉昆虫,印度谷斑螟Plodia interpunctella(Hbner)是危害明亮熊蜂繁育的主要害虫之一。2年的研究结果表明,印度谷斑螟的形态特征与危害蜜蜂巢房的大蜡螟Gallerie mellonellaL.和小蜡螟Achroia grisella Fabricius明显不同。印度谷斑螟以饲喂熊蜂的花粉为载体传播进熊蜂繁育室,在熊蜂繁育室内可以连续繁殖,1年发生6～8代,且世代重叠。印度谷斑螟幼虫主要以蜂群内的剩花粉为食,当花粉不足时,就开始取食巢房和蜂蛹,对熊蜂的规模化繁育危害较大,每年的5～8月、11～2月为危害高峰期。印度谷斑螟的发育受环境和食物的影响很大,在温度为28℃、相对湿度为60%熊蜂繁育室内,印度谷斑螟的卵期为4d,幼虫期为19～23d,蛹期为11d,成虫期为4～20d。成虫羽化后3～4h即可进行交配,雌蛾交配后当天就开始产卵,产卵期4～10d不等,平均产卵量107.8粒。在熊蜂繁育室消毒期间,食物短缺,印度谷斑螟幼虫进入休眠状态,各龄幼虫均可发生休眠现象。印度谷斑螟不危害蜜蜂,在蜜蜂巢房中不能存活。     

Effect of Bacillus thuringiensis on Habrobracon hebetor during combined biological control of Plodia interpunctella

Abstract  The suitability of combining microbial pesticides and an insect parasitoid for pest management of stored cereal in China was evaluated using laboratory assays. For this purpose, interactions between Bacillus thuringiensis ( Bt ), Bt -intoxicated host larvae and the parasitoid Habrobracon hebetor (Say) (Hymenoptera: Braconidae) were tested against Plodia interpunctella Hübner (Lepidoptera: Pyralidae) . Bt or H. hebetor alone caused 41.67% and 35.35% P. interpunctella larval mortality respectively. The Bt –parasitoid combined treatment significantly increased mortality of P. interpunctella (86%). Progeny development of H. hebetor was dependent upon its susceptibility to Bt . Fewer parasitoids emerged from Bt –parasitoid combined treatment than in non- Bt treatments. However, since Bt did not prevent parasitoid development, a combined treatment with Bt and parasitoid release could produce better protection against P. interpunctella than either treatments when used singly, because their lethal effects were additive to each other.     

Biology and development of some stored grain pests as affected by δ‐endotoxin and β‐exotoxin of Bacillus thuringiensis

Exposure of Plodia interpunctella and Sitotroga cerealella to sublethal concentrations of Dipel 2X® (Bacillus thuringiensis var.kurstaki‐HD‐1)with its spores and endotoxin crystals led to an increase in the sum of larval‐pupal duration. A decrease in moth emergence, egg production and fertility was observed with increase of Dipel 2X concentration, while the longevity of the moths was not affected by treatment. Sublethal concentrations of β‐exotoxin (ABG‐6162 A) had no significant effect on the sum of larval—pupal duration of either insect species. Percentage of moth emergence decreased with the increase of β‐exotoxin concentrations. The longevity of both male and female adults of P. interpunctella and of females of S. cerealella were shorter at high concentrations. Egg production in P. interpunctella was reduced by all concentrations of the β‐exotoxin, and hatching of eggs was reduced by concentrations of 15 ppm and above.     

光学相干层析分子成像方法初探

介绍了分子对比剂在光学相干层析成像(optical coherence tom ography,OCT)技术中的研究现状,概述了迄今出现的几种不同的光学相干层析分子成像方法(m olecu lar contrast OCT,简称为MCOCT),讨论了MCOCT的几个重要的实际问题:对比剂的选择范围、激发光强的限制、各种方法灵敏度比较以及MCOCT应用于临床与生物学领域需要考虑的因素。     

温度对麦蛾柔茧蜂功能反应的影响

为明确温度变化在麦蛾柔茧蜂Habrobracon hebetor对印度谷螟Plodia interpunctella寄生作用中的影响, 研究了室内17, 20, 23, 26, 29, 32和35℃条件下, 麦蛾柔茧蜂对不同密度的印度谷螟5龄幼虫的麻痹和寄生作用。结果表明: 在17～29℃范围内, 寄生蜂的寄主处理时间与温度成反比, 从17℃的0.341 d到29℃的0.068 d, 但温度再升高时, 处理时间又延长。寄主搜索率也随温度的改变而变化, 17℃时最低, 为0.056; 29℃时最高, 为1.895; 当温度升高到32～35℃时, 寄主搜索率又下降。温度调节的功能反应模型表明, 在26～29℃范围内, 寄生率较高。可见, 在26～29℃时, 麦蛾柔茧蜂对印度谷螟有较好的寄生效果, 对寄生蜂繁殖后代有利。     

Influences of sex, size, and symmetry on ejaculate expenditure in a moth

Although sperm fundamentally function to fertilize eggs, forcesarising from both sexes select for optimal ejaculate composition.Sperm competition is one recognized agent in the evolution ofsperm and ejaculate structure. Few studies, however, have examinedhow female factors influence ejaculate structure, despite somebehavioral evidence for male mate choice. Male Plodia interpunctella(Lepidoptera, Pyralidae) accrue all resources for reproductionas larvae. Adults emerge with a limited sperm complement andare therefore under intense selection to optimize gamete allocation.I detected no effect of male body weight on ejaculate size.However, female reproductive potential (ovary masses) was dictatedby body weight In addition, heavier females had greater spermathecalvolumes, but there was no such relationship with bursal size.Finally, heavier females showed a higher mating frequency. Ifound that mating males were sensitive to female size and producedlarger ejaculates when mating with heavier females. Males mayejaculate more sperm into larger females either because it paysthem to "spend" more reproductive resources on matings thatprovide greater reproductive potential, or because heavier (longerlived and more attractive) females mate more frequently andhave larger spermathecal volumes. Alternatively, females maycontrol spermatophore formation and "accept" an appropriateejaculate to maximize fertility. Males may therefore be alsoselected to ejaculate more sperm into larger females to counteractgreater risks of sperm competition associated with heavier females.There was no association between male or female femur asymmetryand ejaculate size. P.interpunctella may be selected to exercisemodulation of ejaculate size because males invest paternally,sperm for the single reproductive episode are limited, and femalefecundity and mating pattern vary between individuals and areassociated with body weight. More obvious variability in malereproductive behavior and choice may therefore be paralleledat the cryptic gametic level by plasticity in ejaculate allocation.     

The question of paternal investment in Lepidoptera: male-contributed proteins in Plodia interpunctella

In Plodia interpunctella, radioactive labelling techniques indicate that male-derived substances, transferred to the female during copulation, enter unfertilized eggs. These substances are proteinaceous and the cumulative amount of material entering the unfertilized eggs increases with time since mating. Following courtship, smaller males complete coupling with females at a lower frequency than larger males. Smaller males also transfer smaller (by weight) ejaculates than larger males. Ejaculate weight is about 4% of male body weight in P. interpunctella. However, neither fecundity nor the number of deposited eggs are a function of ejaculate weight. Consequently, ejaculate materials cannot be designated a form of paternal investment, despite the observed transfer to unfertilized eggs.