Interference Efficiency and Effects of Bacterium-mediated RNAi in the Fall Armyworm (Lepidoptera: Noctuidae)

RNAi is an effective tool for gene function analysis and a promising strategy to provide environmentally friendly control approaches for pathogens and pests. Recent studies support the utility of bacterium-mediated RNAi as a cost-effective method for gene function study and a suitable externally applied delivery mechanism for pest control. Here, we developed a bacterium-mediated RNAi system in Spodoptera frugiperda based on four target genes, specifically, Chitinase (Sf-CHI), Chitin synthase B (Sf-CHSB), Sugar transporter SWEET1 (Sf-ST), and Hemolin (Sf-HEM). RNAi conducted by feeding larvae with bacteria expressing dsRNAs of target genes or injecting pupae and adults with bacterially synthesized dsRNA induced silencing of target genes and resulted in significant negative effects on growth and survival of S. frugiperda. However, RNAi efficiency and effects were variable among different target genes and dsRNA delivery methods. Injection of pupae with dsCHI and dsCHSB induced a significant increase in wing malformation in adults, suggesting that precise regulation of chitin digestion and synthesis is crucial during wing formation. Injection of female moths with dsHEM resulted in lower mating, fecundity, and egg hatching, signifying a critical role of Sf-HEM in the process of egg production and/or embryo development. Our collective results demonstrate that bacterium-mediated RNAi presents an alternative technique for gene function study in S. frugiperda and a potentially effective strategy for control of this pest, and that Sf-CHI, Sf-CHSB, Sf-ST, and Sf-HEM encoding genes can be potent targets.     

Projecting the Global Potential Distribution of Cydia pomonella (Lepidoptera: Tortricidae) Under Historical and RCP4.5 Climate Scenarios

The codling moth Cydia pomonella (L.) (Lepidoptera: Tortricidae) is a destructive pest of apple (Malus domestica (Rosales: Rosaceae)), pear (Pyrus spp. (Rosales: Rosaceae)), and other pome tree fruits; outbreaks cause significant ecological and economic losses. In this study, we used CLIMEX model to predict and evaluate the global risk of C. pomonella based on historical climate data (1989–2018) and simulated future climate data (2071–2100) under the RCP4.5 scenarios. Cydia pomonella exhibited a wide distribution under both historical and future climate conditions. Climate change is predicted to expand the northern boundary of the potential distribution from approximately 60°N to 75°N. Temperature was the most dominant factor in climatic suitability for the pest. Combinations of multiple meteorological factors (relative humidity and precipitation) associated with a failure to break diapause in certain regions also affect suitability, particularly in northern South America and central Africa. Irrigation only had a slight impact on species favorability in some areas. The projections established in our study present insight into the global potential suitability of C. pomonella under climate change scenarios by the end of the 21st century. Farmers should be aware of the risk associated with the pest based on the results, which would provide guidance for quarantine agencies and trade negotiators worldwide.     

Adaptation of Habrobracon hebetor (Hymenoptera: Braconidae) to Rearing on Ephestia kuehniella (Lepidoptera: Pyralidae) and Helicoverpa armigera (Lepidoptera: Noctuidae)

Food characteristics strongly regulate digestive enzymatic activity of insects through direct influences on their midgut mechanisms. Insect performance is better on diets that contain nutrients in proportions that fit its digestive enzymes. Little is known about the influences of rearing history on parasitism success of Habrobracon hebetor Say. This research focused on the effect of nutrient regulation on survival, development, and parasitism of H. hebetor. Life history and digestive enzyme activity of fourth-stage larvae of H. hebetor were studied when reared on Ephestia kuehniella Zeller. This parasitoid was then introduced to Helicoverpa armigera (Hübner), and above-mentioned parameters were also studied in the first and fourth generations after transfer. In term of parasitism success, H. hebetor preferred E. kuehniella over He. armigera. When the first and fourth generations of He. armigera-reared H. hebetor were compared, the rearing history affected the life history and enzymatic activity of the parasitoid. A better performance of H. hebetor was achieved after it was reared on He. armigera for the four generations. Because, digestive α-amylase and general protease of the parasitoid were matched with the new host, it used reserve energy for a better performance. Thus, a better performance of H. hebetor could be obtained when the parasitoid was reared on its original host for at least four generations.     

小麦干旱胁迫对黏虫取食及食物利用效率的影响

为了解小麦干旱对食叶害虫黏虫食物利用效率的影响,采用PEG-6000模拟干旱处理小麦植株,设置对照(0g·mL-1)、低(0.05g·mL-1)、中(0.1g·mL-1)和强(0.2g·mL-1)4个干旱胁迫水平,以盆栽小麦饲喂黏虫幼虫,观察黏虫取食及食物利用效率。协方差分析表明,干旱胁迫对黏虫幼虫的体质量、取食量有显著影响,但对食物利用量没有显著影响。与对照相比,强干旱胁迫下黏虫取食量减少10.4%,幼虫体质量增加量减少10.6%。经食物利用指数方法分析,干旱胁迫显著影响黏虫的近似消化率和食物转化率,强干旱胁迫下食物转化率较对照减小了8.0%,近似消化率增加10.5%;干旱胁迫对其他食物利用指数均无显著影响。以上结果说明,小麦中度和强度干旱胁迫可对黏虫营养利用效率造成不良影响。     

Temperature Effects on the Development and Reproduction of Three Trichogramma (Hymenoptera: Trichogrammatidae) Species Reared on Trichoplusia ni (Lepidoptera: Noctuidae) Eggs

The cabbage looper, Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae) is a generalist species and an important pest of Brassicaceae worldwide. Egg parasitoids are a feasible alternative for the control of this species. We evaluated the suitability of T. ni eggs as hosts for three Trichogramma Westwood (Hymenoptera: Trichogrammatidae) species and their tolerance to survive and develop within a range of temperatures between 15 and 30°C under laboratory conditions. The species evaluated were Trichogramma pretiosum Riley, Trichogramma atopovirilia Oatman and Platner, and Trichogramma acacioi Brun, Moraes and Soares. Parasitism rate was affected by temperature, parasitoid species, and by the interaction between these two factors. Parasitoids developed and reproduced in the range of temperatures evaluated, but Trichog. acacioi failed to parasitize T. ni eggs at 30°C. The highest parasitism rates of Trichog. atopovirilia and Trichog. pretiosum occurred at 20 and 25°C and Trichog. acacioi at 25°C, with parasitism rate above 70% in the three species. Parasitoid emergence was not affected by temperature or species. The estimated thermal constant and lower temperature threshold were 134.6 DD and 10.6°C for Trichog. pretiosum and 130.1 DD and 11.2°C for Trichog. atopovirilia. The results demonstrated that Trichog. pretiosum and Trichog. atopovirilia are the most suitable species for the control of T. ni, as they can remain active throughout the year in subtropical regions.     

Comparative Efficacy of CO2 and Ozone Gases Against Ephestia cautella (Lepidoptera: Pyralidae) Larvae Under Different Temperature Regimes

Comparative efficacy of three different modified atmospheres: 100% CO₂, 75% CO₂ + 25% N₂, and 22 ppm ozone were examined against larval mortality of the almond moth, Ephestia cautella (Walker) (Lepidoptera: Pyralidae) at temperature regimes of 25°C and 35 ± 2°C and 60 ± 5% relative humidity, and 9:15 dark and light. Wandering young larval instars, which are fast growing, large enough in size and considered as more tolerant to modified atmosphere, were collected directly from the rearing culture, placed inside pitted date fruits of vars.: “Khudri,” “Ruziz,” and “Saqie,” were treated with aforementioned gases for 24, 48, and 72 h. The immediate and delayed larval mortality was recorded after each exposure timing. Ozone possessed the strongest fumigant toxicity causing 100% mortality with all varieties, at 25 and 35°C after 24 h exposure and was more effective than 75% CO₂ that caused 83 and 100% immediate mortality with variety ruziz at 25 and 35°C, respectively. Extending the treatments exposure time to 72 h, 100% mortality was recorded by exposing larvae to any of the studied gases at 25 and 35°C. These results suggest that gases and temperature used in this study can be effectively used to control E. cautella in dates and stored grains.     

温湿度对茶小卷叶蛾生长发育的影响

研究结果表明,茶小卷叶蛾(Adoxophyes orana Fischer von Roslerstamm)卵期发育起点 C=9.57±0.64(℃),有效积温常数 K=110.08±4.29(日度),预测式:N=(110.08±4.29)/(T-(9.57±0.64));幼虫期 C=4.94±2.48(℃),K=450.75±54.70(日度),N=(450.75±54.70)/(T-(4.94±2.48));蛹期 C=8.0±1.15(℃),K=130.83±8.58(日度),N=(130.83±8.     

Influence of Different Types of Phyllostachys pubescens (Poales: Poaceae) Leaves on Population Parameters of Pantana phyllostachysae (Lepidoptera: Lymantriidae) and Parasitic Effects of Beauveria bassiana (Moniliales: Moniliaceae)

We found that Pantana phyllostachysae, a dangerous pest of moso bamboo (Phyllostachys pubescens), showed differences in growth and development after feeding on diverse types of moso bamboo leaves. The mortality rate of Pa. phyllostachysae due to Beauveria bassiana, an entomopathogenic fungus, was also affected by the varied larval diet. Larval and pupal developmental duration of Pa. phyllostachysae was longer when feeding on “off-year” bamboo leaves. Pupal weight and adult fertility were higher when feeding on “on-year” bamboo leaves. Mortality due to B. bassiana was significantly lower in larvae fed on on-year bamboo leaves than in larvae fed on off-year bamboo leaves. Larvae fed on new bamboo leaves had a shorter development period and higher survival rate than those fed on off-year bamboo leaves. However, mixed feed (mixture of new, on-year, and off-year bamboo leaves) decreased the egg production of Pa. phyllostachysae. After infection by the second generation of B. bassiana, the survival time of Pa. phyllostachysae fed on mixed feed increased significantly compared with the first generation. We also fed Pa. phyllostachysae different proportion of new bamboo leaves in mixed feed to simulate natural conditions. We found that increasing the proportion of new bamboo leaves in the food promoted pupal development and increased egg production; it also increased the resistance of larvae to the first generation of B. bassiana. The pathogenicity of the second generation of B. bassiana declined in all mixed feed treatments.     

快速冷耐受对水稻二化螟滞育幼虫的生理效应

 为从生理生化水平上探讨快速冷耐受(RCH)对二化螟滞育幼虫的生理效应,分别对正常饲养(CK)、非快速冷耐受(NRCH)和RCH处理过的二化螟幼虫的水分、脂质、总糖、小分子碳水化合物含量及SOD、POD、CAT活性进行了测定。结果表明,RCH处理组水分含量较对照组显著下降,POD活性对照组显著上升,脂质、总糖、海藻糖、葡萄糖、甘油含量及SOD和CAT活性无显著差异;NRCH处理组水分含量较对照组显著降低,而POD活性则显著下降,其余未见显著变化;RCH处理组仅见POD活性较对照组显著增加。由此可见,RCH处理对二化螟滞育幼虫体内水分和POD诱导效应显著。     

Host Plant Associations and Parasitism of South Ecuadorian Eois Species (Lepidoptera: Geometridae) Feeding on Peperomia (Piperaceae)

The very species-rich tropical moth genus Eois Hübner (Lepidoptera: Geometridae) is a promising model group for studying host plant specialization and adaptive radiation. While most Eois species are assumed to be specialized herbivores on Piper L. species, records on other plant taxa such as Peperomia Ruiz & Pavón (Piperaceae) are still relatively scarce. Moreover, little is known about life history traits of most species, and only a few caterpillars have been described so far. We collected caterpillars associated with Peperomia (Piperaceae) host plants from June 2012 to January 2013 in three elevational bands of montane and elfin rainforests on the eastern slopes of the Andes in southern Ecuador. Caterpillars were systematically searched and reared to the adult stage. We were able to delimitate ten species of Eois on Peperomia by comparison of larval and adult morphology and by using 658 bp fragments of the mitochondrial COI gene (barcode sequences). Three of these species, Eois albosignata (Dognin), Eois bolana (Dognin), and Eois chasca (Dognin), are validly described whereas the other seven taxa represent interim morphospecies, recognized unequivocally by their DNA barcodes, and their larval and adult morphology. We provide information about their host plants, degree of parasitism, and describe the larval stages in their last instar. Additionally, caterpillars and moths are illustrated in color plates. This is the first comparative study dealing with Eois moths whose caterpillars feed on Peperomia hosts.     

Sexual Dimorphism and Allometric Effects Associated With the Wing Shape of Seven Moth Species of Sphingidae (Lepidoptera: Bombycoidea)

Sexual dimorphism is a pronounced pattern of intraspecific variation in Lepidoptera. However, moths of the family Sphingidae (Lepidoptera: Bombycoidea) are considered exceptions to this rule. We used geometric morphometric techniques to detect shape and size sexual dimorphism in the fore and hindwings of seven hawkmoth species. The shape variables produced were then subjected to a discriminant analysis. The allometric effects were measured with a simple regression between the canonical variables and the centroid size. We also used the normalized residuals to assess the nonallometric component of shape variation with a t-test. The deformations in wing shape between sexes per species were assessed with a regression between the nonreduced shape variables and the residuals. We found sexual dimorphism in both wings in all analyzed species, and that the allometric effects were responsible for much of the wing shape variation between the sexes. However, when we removed the size effects, we observed shape sexual dimorphism. It is very common for females to be larger than males in Lepidoptera, so it is expected that the shape of structures such as wings suffers deformations in order to preserve their function. However, sources of variation other than allometry could be a reflection of different reproductive flight behavior (long flights in search for sexual mates in males, and flight in search for host plants in females).     

Developmental Biology and Effects of Adult Diet on Consumption,Longevity, and Fecundity of Colaspis crinicornis (Coleoptera: Chrysomelidae)

The chrysomelid beetle Colaspis crinicornis Schaeffer (Coleoptera: Chrysomelidae) occurs primarily in the Great Plains region of the United States. Little is known about the biology and ecology of this species, but over the last decade, it has become increasingly common in the corn, Zea mays L., and soybean, Glycine max (L.) Merrill, agroecosystem of southeastern Nebraska. As part of a larger comprehensive project to understand the natural history and pest potential of this species, laboratory experiments were conducted to study the developmental biology, morphological characters of immature stages, and the effect of adult diet on consumption, longevity, and fecundity. Females readily deposited egg clusters in the soil, and percentage egg hatch was high under laboratory conditions. Larvae and pupae were confirmed to be soil-dwelling stages. C. crinicornis has relatively short egg, pupal, and adult stages with the majority of its life cycle spent in the larval stage. Results of choice and no-choice adult feeding experiments indicate that diets of corn or soybean leaves did not significantly affect consumption, longevity, or fecundity of adult C. crinicornis, suggesting that corn and soybean leaves are similarly suitable food sources for adults. The ability to effectively utilize tissues from very different plant families as adult food sources suggests that C. crinicornis is polyphagous in the field.     

土壤添加生物质炭对黏虫生长发育和生殖的影响

为探究土壤添加生物质炭对植食性咀嚼式口器害虫的影响,选用黏虫为研究对象,设0、15、30和50g·kg~(-1)四个土壤添加生物质炭处理,对盆栽种植的麦苗接初孵黏虫幼虫,观察和分析幼虫生长发育和成虫生殖力的变化。结果表明,随生物质炭施用量的增大,黏虫幼虫发育历期呈线性缩短趋势,50g·kg~(-1)生物质炭处理下幼虫发育历期为19.0d,较不添加生物质炭处理下降6.5%。黏虫蛹鲜重随生物质炭添加量增大呈线性减小趋势,其中50g·kg~(-1)生物质炭处理下雌虫蛹鲜重为0.28g,较不添加生物质炭处理下降12.5%。施加生物质炭对黏虫的化蛹率(平均69.89%)和羽化率(92.08%)无显著影响。但随生物质炭施用量的增大,黏虫产卵量呈线性增大的趋势,50g·kg~(-1)生物质炭处理产卵量为605粒,较不添加生物质炭处理下增加近3.3倍。以上结果说明,施用生物质炭有提高黏虫生殖潜力的作用。     

Effects of Low-Phosphorus Stress on Membrane Lipid Peroxidation and Protective Enzyme Activities in Leaves of Different Rice （Oryza sativa） Cultivars

Membrane lipid peroxidation and protective enzyme activity in leaves of low-phosphorus-tolerant rice cultivars Dalidao and Liantangzao 3, and low-phosphorus-sensitive cultivars Huzhanqi and Xinsanbaili were studied under low phosphorus stress with sandy culture. Results indicated that low-phosphorus stress aggravated the membrane lipid peroxidation in rice leaves, and it was more severe in low-phosphorus-sensitive cultivars than that in low-phosphorus-tolerant cultivars. During the period of low-phosphorus stress, the activities of SOD, CAT and POD maintained relatively stable in low-phosphorus-tolerant cultivars, whereas those increased obviously at early stage and subsequently decreased rapidly in the low-phosphorus-sensitive cultivars, suggesting that the absolute activities of protective enzymes had no relation with the low-phosphorus stress, while the changing trend was reverse.     

Influence of drought stress on Mexican rice borer (Lepidoptera: Crambidae) oviposition preference in sugarcane

Two sugarcane, Saccharum hybrids, varieties were grown in the greenhouse under well watered or drought conditions to examine the influences of stress on Mexican rice borer, Eoreuma loftini (Dyar), oviposition preference and selected nutritional components without impinging factors common to field conditions that alter responses. Our research revealed that, under controlled conditions, drought induced a wider range and greater uniformity of free amino acid (FAA) accumulations than have been previously reported. Drought stress resulted in increased dry leaf tissue and elevated concentrations of 7 of 9 detectable free essential (for insect health) amino acids in stalks, the chief food of Mexican rice borer larvae. Stressed sugarcane was preferred for oviposition, likely related to greater numbers of dry leaves and heightened host plant nutritional quality. Dry leaf tissue, which is not consumed, may be a cue for improving chances of larvae encountering nutrient-enhanced living tissue, and for concealing eggs in folds. Excised dry leaf tissue from the treatments was indistinguishable for oviposition preference; therefore, biochemical status of living tissue may provide oviposition cues. Varieties exhibited no major genotypic differences in FAA accumulations or oviposition preference.     

缺镁对龙眼叶组织活性氧代谢及膜系统的影响

通过水培试验,研究缺镁对龙眼幼苗叶组织活性氧代谢及膜脂过氧化作用的影响。结果表明,随着缺镁症状加重,龙眼叶片细胞内Ｋ＋外渗量,ＭＤＡ含量、Ｏ２净产生速率和Ｈ２Ｏ２含量增加,活性氧清除系统的酶（ＳＯＤ、ＡＳＡ—ＰＯＤ、ＧＲ）活性提高。抗氧化物质（ＡｓＡ、ＧＳＨ）含量先升高,后下降。缺镁龙眼叶片抗氧化物含量和活性氧清除酶活性的提高是龙眼抵御活性氧伤害的一种适应性反应。缺镁龙眼活性氧伤害的原因可能与龙眼ＣＯ２同化能力下降,光合产物运转受阻有关。      

Prevalence of Helicoverpa zea (Lepidoptera: Noctuidae) on late season volunteer corn in Mississippi: Implications on Bt resistance management

The southern United States has a long growing period between corn, Zea mays L., harvest and first winter frost, so volunteer corn which germinates after harvest has a growing period sufficient for corn earworm, Helicoverpa zea (Boddie) and fall armyworm, Spodoptera frugiperda (J. E. Smith) to feed on these plants. However, lower air temperatures can limit larval development on late season volunteer corn and thereby successful pupation. Here we explore the suitability of late season volunteer corn for larval development and the potential contribution of H. zea larvae to the overwintering population. Our survey revealed the occurrence of volunteer corn in high densities, with monthly mean densities ranging from 56,000 to 143,000 plants ha⁻¹. H. zea larvae were found feeding on both vegetative and reproductive stage plants while S. frugiperda were only found on vegetative stage plants. An analysis of H. zea growing degree day (GDD) accumulations based on Mississippi weather data from 1980 to 2010 revealed that sufficient GDD to reach prepupation would always be accumulated before first frost if oviposition occurred by 9 September, with the probability of successful pupation decreasing rapidly thereafter. However, most of the H. zea larvae were oviposited after this, and could not reach pupation. Because S. frugiperda cannot overwinter in Mississippi, their ability to pupate was not examined. Low suitability of whorl stage corn for H. zea development coupled with low larval densities during this stage effectively diminish the number of larvae that complete development on late season volunteer transgenic corn expressing genes from the soil bacterium, Bacillus thuringiensis (Bt). This limits the Bt resistance risk posed by larvae developing on late season volunteer corn in all but the most southern locations in the US.     

曙暮光在光敏感核不育水稻两个光周期反应中的作用

 本文论证了曙暮光在光敏感核不育水稻两个光周期反应中均有明显的作用,初步探明农垦58S 在武汉地区(30°27′N)育性转换期(7—8月)曙暮光的变化规律,提出采用“光照长度”以代替“日照长度”来划分光周期的昼与夜更为准确的见解,据此讨论了曙暮光的作用对光敏感核不育水稻在不同地理条件下的生态适应性的重要影响。     

Effect of Different Wheat-Based Diets and Corn Meal Addition on Development Parameters of Ephestia kuehniella (Zeller, 1879) (Lepidoptera: Pyralidae)

The expansion of Integrated Pest Management (IPM), including biological control, has had several positive consequences for the agricultural environment and participants in the production chain. To enable successful operation and applications of biological control, production of insects used for rearing natural enemies (parasitoids and predators) must be optimized to reduce time and costs and improve production both qualitatively and quantitatively. The present study evaluated the effect of wheat varieties, the main component of artificial diets for Ephestia kuehniella, on the reproductive performance and biological parameters of this flour moth, which is used for mass production of Trichogramma spp. (Hymenoptera: Trichogrammatidae) and other parasitoids and predators. Four varieties of wheat were compared: BRS 327, BRS Marcante, BRS Parrudo, and KBR, with and without the addition of corn E. kuehniella reared on 97% BRS 327 wheat flour + 3% nutritional yeast had the best biological parameters and substitution of corn for about half of the wheat increased the number of eggs per female.     

气候变化下红茴砂在中国潜在适生区的最大熵生态位模型预测

红茴砂是姜科茴香砂仁属多年生草本植物,我国仅在海南地区有自然分布,是具有很高药用价值的濒危植物。为了解红茴砂在未来气候变化下的潜在适生区及其主要环境影响因子,以期对红茴砂的保育提供科学指导,将45条红茴砂分布位点数据与20个环境因子相结合,运用最大熵生态位模型MaxEnt和ArcGIS软件模拟了当前气候和未来2050年RCP2.6和RCP8.5两种不同气候条件下红茴砂在中国的潜在分布区,并分析影响红茴砂分布的主导环境因子。结果表明：当前气候条件下,红茴砂适生区总范围在18°~32° N、27°~122° E,面积约为1.24×10⁶ km²,主要集中分布在海南、贵州、福建、广东、广西、云南等地;影响红茴砂地理分布的主导环境因子为最湿月降水量、最暖季度降水量、年均温度变化范围、最冷月份最低温、海拔和最热季度均温,累计贡献率达87%;在未来2050年RCP2.6和RCP8.5两种不同气候情景下,红茴砂适生区域丧失面积均达到95%以上,潜在分布区缩小到云南、四川、西藏、贵州和台湾这5个省区,新增区域主要在西藏东南部和四川中南部,同时潜在总适生区和高适生区的质心有向西北方迁移的趋势。