Optimization of parental RNAi conditions for hunchback gene in Locusta migratoria manilensis (Meyen)

An investigation on the optimization of parental RNA interference (RNAi) conditionsfor hunchback {hb) gene in Locusta migratoria manilensis (Meyen) was conducted.Double stranded RNA (dsRNA) corresponding to hb gene was injected into haemocoel offemale adults of L.migratoria manilensis.Embryos developed from the eggs laid by theinjected adults on the 7th day after eclosion showed observable effects of RNAi for hb.Thesilencing effect after delivery treatment of dsRNA for hb gene was maintained for moretha...     

Development of the tympanal organ in larvae of the migratory locust (Locusta migratoria)

Summary The tympanal organ of the migratory locust acquires its definitive form during larval development. All the receptor cells (90–100) are present in the 1st instar, whereas the differentiation of the tympanum and the cuticular structures it bears proceeds in steps from one instar to the next. The elevated process is the earliest such structure to appear (2nd instar); it is followed by the pyriform vesicle (3rd instar) and folded body (4th instar). The styliform body first appears in the imago. Although the typical arrangement of the receptor cells is already discernible in the 1st instar, some of the attachment sites change during development, the final configuration appearing only in the imago.Supported by the Deutsche Forschungsgemeinschaft (Ka 498/2)     

Thiol-activated serine proteinases from nymphal hemolymph of the African migratory locust,Locusta migratoria migratorioides

Two unique serine proteinase isoenzymes (LmHP-1 and LmHP-2) were isolated from the hemolymph of African migratory locust (Locusta migratoria migratorioides) nymphs. Both have a molecular mass of about 23 kDa and are activated by thiol-reducing agents. PMSF abolishes enzymes activity only after thiol activation, while the cysteine proteinase inhibitors E-64, iodoacetamide, and heavy metals fail to inhibit the thiol-activated enzymes. The N-terminal sequence was determined for the more-abundant LmHP-2 isoenzyme. It exhibits partial homology to that of other insect serine proteinases and similar substrate specificity and inhibition by the synthetic and protein trypsin inhibitors pABA, TLCK, BBI, and STI. The locust trypsins LmHP-1 and LmHP-2 constitute a new category of serine proteases wherein the active site of the enzyme is exposed by thiol activation without cleavage of peptide bonds.     

Isolation,characterization and cross‐species amplification of eight microsatellite DNA loci in the migratory locust (Locusta migratoria)

Eight polymorphic di‐ and trinucleotide microsatellite loci suitable for population genetic analysis were developed in Locusta migratoria from a partial phagemid genomic library enriched for microsatellite inserts. The expected heterozygosity at these loci ranges from 0.45 to 0.97, with the observed allele numbers varying between nine and 45. The overall microsatellite cloning efficiency in L. migratoria is 14%, suggesting that in migratory locusts, microsatellite sequences are abundant and should provide a valuable and easily accessible source of nuclear markers for genetic studies. These microsatellite loci were highly Locusta‐specific, with only very limited cross‐species applicability.     

Fecal volatile components elicit aggregation in the oriental migratory locust,Locusta migratoria manilensis (Orthoptera: Acrididae)

Abstract The aggregation components from fecal volatiles of the oriental migratory locust, Locusta migratoria manilensis were identified with gas chromatographic/electroantennographic detector (GC‐EAD), GC‐MS (mass spectrometry) analyses and behavioral bioassays. Both last instar nymphs and adults of the oriental migratory locust have similar aggregation pheromones in their volatiles. A total of 11 electrophysiologically active compounds, namely, hexanal, cyclohexanol, heptanal, phenol, 2,5‐dimethyl‐pyrazine, benzyl alcohol, benzaldehyde, guaiacol, nonanal, 2,6,6‐trimethyl‐2‐cyclohexene‐1,4‐dione and decyl aldehyde were identified in the fecal volatiles of 2‐day‐old immature adult male locusts. Only hexanal, nonanal, benzaldehyde, cyclohexanol and 2,5‐dimethyl‐pyrazine elicited significant aggregation responses in immature 2‐day‐old adult males. However, adult males had significantly lower behavioral responses to synthetics of five single compounds than the blend of cyclohexanol, 2,5‐dimethyl‐pyrazine, benzaldehyde, nonanal, hexanal in ratios of 100: 100: 2: 60: 30 in the range of 30–60 μg/mL. We propose that it is the blend of these five compounds that plays a key role in eliciting and sustaining aggregation in gregarious oriental migratory locusts. These results also showed that the aggregation pheromones of the oriental migratory locust are significantly different from those found in the desert locust.     

Cuticular protein LmTwdl1 is involved in molt development of the migratory locust

The cuticle, an essential structure for insects, is produced from cuticular proteins and chitin via a series of biochemical reactions. Tweedle genes are important members of the cuticular protein family and have four conserved motifs binding to chitin. Tweedle family genes have been found to play a profound effect on cuticle development. Here, we report that the cuticular protein gene LmTwdl1 of Locusta migratoria belongs to the Tweedle family. In situ hybridization showed that LmTwdl1 is localized to epidermal cells of the cuticle. The expression patterns of LmTwdl1 showed low expression in the cuticle during the early and middle stages of the fifth‐instar nymphs; in contrast, its expression rapidly increased in the late stages of fifth‐instar nymphs. We performed RNA interference to examine the function of LmTwdl1 in locusts. Silencing of LmTwdl1 resulted in high mortality during the molting process before the next stage. Also, the epicuticle of nymphs failed to molt, tended to be thinner and the arrangement of chitin in the procuticle appeared to be disordered compare to the control group. These results demonstrate that LmTwdl1 plays a critical role in molting, which contributes to a better understanding of the distinct functions of the Tweedle family in locusts.     

Mechanisms of organophosphate resistance in a field population of oriental migratory locust, Locusta migratoria manilensis (Meyen)

The susceptibilities to three organophosphate (OP) insecticides (malathion, chlorpyrifos, and phoxim), responses to three metabolic synergists [triphenyl phosphate (TPP), piperonyl butoxide (PBO), and diethyl maleate (DEM)], activities of major detoxification enzymes [general esterases (ESTs), glutathione S-transferases (GSTs), and cytochrome P450 monooxygenases (P450s)], and sensitivity of the target enzyme acetylcholinesterase (AChE) were compared between a laboratory-susceptible strain (LS) and a field-resistant population (FR) of the oriental migratory locust, Locusta migratoria manilensis (Meyen). The FR was significantly resistant to malathion (57.5-fold), but marginally resistant to chlorpyrifos (5.4) and phoxim (2.9). The malathion resistance of the FR was significantly diminished by TPP (synergism ratio: 16.2) and DEM (3.3), but was unchanged by PBO. In contrast, none of these synergists significantly affected the toxicity of malathion in the LS. Biochemical studies indicated that EST and GST activities in the FR were 2.1- to 3.2-fold and 1.2- to 2.0-fold, respectively, higher than those in the LS, but there was no significant difference in P450 activity between the LS and FR. Furthermore, AChE from the FR showed 4.0-fold higher activity but was 3.2-, 2.2-, and 1.1-fold less sensitive to inhibition by malaoxon, chlorpyrifos-oxon, and phoxim, respectively, than that from the LS. All these results clearly indicated that the observed malathion resistance in the FR was conferred by multiple mechanisms, including increased detoxification by ESTs and GSTs, and increased activity and reduced sensitivity of AChE to OP inhibition.     

河北省南大港农场2002年夏蝗发生特点及原因浅析

进入 90年代以来 ,南大港蝗区东亚飞蝗Locustamigratoriamanilensis(Meyen)大发生 6次 ,2 0 0 1年夏秋蝗发生面积达 2 6万hm2 ,5龄蝗蝻最高密度为 1 0 0 0 0头 m2 。 2 0 0 2年形势更为严峻 ,仅夏蝗发生面积超过 2万hm2 ;分别造成 1 3 0 0hm2 和 2 70 0hm2 的芦苇被吃成光杆和被啃食的严重破叶。出土时间早、孵化时间长、龄期悬殊大是今年夏蝗发生的主要特点。主要原因是去年越冬卵块基数大 ,其次是受气候条件和农业环境的影响     

Influence of soil moisture on egg cold hardiness in the migratory locust Locusta migratoria (Orthoptera: Acridiidae)

Abstract.  The present study investigates the influence of environmental moisture on cold hardiness of the migratory locust, Locusta migratoria . The water content of locust eggs kept in soil at 30 °C varies according to the moisture content of the substrate. In turn, it can significantly affect the supercooling point of locust eggs (range from −26 to −14.8 °C) and the mortality when exposed to subzero temperatures. Environmental moisture influences the supercooling capacity of eggs and their survival at low temperature. When locust eggs of the same water content are exposed to subzero temperatures under different soil moistures, their mortality varies between short-time exposure and long-time exposure at subzero temperatures. Given a short-time exposure, mortality in wet soil is lower than in dry soil due to the buffering effect of soil water against temperature change. The pattern of egg mortality is reversed after long-time exposure at low temperature, suggesting that inoculative freezing may be an important mortality factor. It is suggested that interactions between soil moisture and low temperature can influence the cold hardiness of locust eggs, and partial dehydration is beneficial to over-wintering eggs of the migratory locust.     

Chill injury in the eggs of the migratory locust, Locusta migratoria （Orthoptera： Acrididae）： the time-temperature relationship with high-temperature interruption

Abstract Mortality of the overwintering egg of the migratory locust, Locusta migratoria L. , was attributed to chill injury because of its occurrence well above the egg's super cooling point. In this study, two parameters, upper limit of chill injury zone (ULCIZ) and sum of the injurious temperature (SIT), were used to examine the locust egg's cold hardiness. The value of ULCIZ for the locust egg is 1.06 ± 0.54°C, and the SIT is -329.7 (hour · degree). The superoxide dismutase (SOD) and catalase (CAT) activities changed dramatically after cold stress, indicating that oxygen and hydroxide free radicals are probably efficiently detoxified at low temperatures. It was suggested that the nature of chill injury in locust egg might be a complex of metabolic disorder and a non-proportional decrease in enzymatic reaction and transports, because the LDH activity at low temperature increased significantly and the ATPase activity decreased with prolonged duration of exposure to low temperatures. The results from high temperature interruption revealed that the high temperature intervals significantly increased the survival of locust eggs.     

东亚飞蝗fem-1基因的克隆与表达分析

秀丽隐杆线虫Caenorhabditis elegans fem-1基因是性别决定的关键基因。本研究基于生物信息学方法从东亚飞蝗Locusta migratoria manilensis的转录组数据库中克隆出了线虫fem-1的3个同源基因, 将其分别命名为Lmfem-1a, Lmfem-1b和Lmfem-1c (GenBank登录号分别为AB698670, AB698671和AB698672)。其cDNA序列长度分别为2 233, 2 625和2 142 bp, 分别编码662, 642和638个氨基酸。生物信息学分析显示, Lmfem-1a, Lmfem-1b和Lmfem-1c分别含有6, 8和8个典型的锚蛋白重复序列模体。组织表达谱分析发现, Lmfem-1a, Lmfem-1b和Lmfem-1c基因在检测的所有组织中都有表达, 但均在精巢中的表达水平最高, 说明Lmfem-1a, Lmfem-1b和Lmfem-1c基因可能参与东亚飞蝗的多种生理过程, 并受到严格的表达调控。而且, 随着精巢的发育, Lmfem-1a, Lmfem-1b和Lmfem-1c的表达均逐渐增强, 可能与东亚飞蝗的精子形成有关, 但这3个基因是否参与东亚飞蝗的性别决定还有待进一步研究。     

东亚飞蝗雄性生殖系统组织结构观察及三维可视化数字模型

本文研究东亚飞蝗Locusta migratoria manilensis(Meyen)雄性生殖系统组织解剖结构及三维可视化数字模型的构建。采用石蜡切片技术对东亚飞蝗进行组织切片,脱水、透明、HE染色和拍照;并应用冰冻切片技术将冰冻包埋剂包埋后的飞蝗雄性个体进行连续切片,进行截面图像信息采集,建立数据集;通过Photoshop、Image-Pro Plus(IPP)软件对雄性生殖器官截面图像进行分割、处理、序列化和三维重建。通过试验观察分析东亚飞蝗雄性生殖器官精巢、附腺、输精管、精球囊和射精囊及交配器的组织构造;并成功构建了飞蝗雄性生殖系统的三维结构可视化数字模型。该模型可以任意旋转,能从不同角度观察,该试验为研究和教学提供了理论基础。     

Measurements of locomotor activity in hatchlings of the migratory locust Locusta migratoria: effects of intrinsic and extrinsic factors

Abstract. The effects of intrinsic and extrinsic factors on locomotor activity in crowd‐reared first‐stadium nymphs of the migratory locust Locusta migratoria are investigated under continuous light conditions using an actograph apparatus. Nymphs show monomodal or bimodal patterns of locomotor activity with respect to the time after the start of measurements, depending on the age. Locomotor activity is suppressed by the presence of grass in nymphs aged 0–2 days old but a peak of activity observed shortly after hatching is not suppressed. The results suggest that newly‐hatched nymphs may try to disperse from the hatching site. Nymphs show higher locomotor activity levels under moist conditions than under dry conditions during the first 5‐h period of measurements. This enhanced locomotor activity may constitute attempts to avoid high humidity. Under dim‐light conditions (2 × 10^?2 Wm^?2), locomotor activity is suppressed during the first half day and increases to a high level thereafter in both grass‐fed and unfed individuals. This increased activity might indicate a possible involvement of circadian rhythms. Background colour has no significant effect on the locomotor activity. The present study provides new aspects of behaviour in nymphs as well as baseline data for behavioural analysis of locust locomotion in relation to phase polyphenism.     

东亚飞蝗UBX结构域包含蛋白基因 LmUBX2 的克隆和表达分析

【目的】UBX结构域包含蛋白是p97/CDC48的辅助因子。p97在泛素化相关的多种细胞过程中起着重要的作用,如依赖泛素 蛋白酶体系统的蛋白质降解和同型膜融合等。本研究旨在克隆东亚飞蝗 Locusta migratoria manilensis (Meyen)的UBX结构域包含蛋白基因,分析其组织和发育表达格局,为进一步研究UBX结构域包含蛋白基因的功能奠定基础。【方法】通过分析东亚飞蝗的转录组数据克隆UBX结构域包含蛋白基因,采用实时定量PCR技术分析该基因在不同发育时期和成虫不同组织中的表达水平。【结果】克隆到东亚飞蝗的一个UBX结构域包含蛋白基因,命名为 LmUBX2。 LmUBX2 开放阅读框长1 020 bp,编码399个氨基酸,预测分子量和等电点分别为37.8 kDa和6.03,与其他UBX结构域包含蛋白的氨基酸一致性为37%~64%,N端和C端分别有一个保守的UBA结构域和UBX结构域。序列比较和系统发育分析发现 LmUBX2 属于SAKS1亚家族。定量分析发现,LmUBX2 在整个生命周期中都有表达,但成虫期的表达水平最高;在检测的所有组织中都有表达,但在精巢和卵巢中表达水平最高。【结论】研究结果说明 LmUBX2 可能参与东亚飞蝗多种生理过程,尤其可能与东亚飞蝗的生殖有关,但还需深入研究。     

两个不同生态特征蝗区东亚飞蝗的两种代谢酶

黄骅和平山是中国河北省两个不同的蝗区,这两个蝗区的生态特征有很大的不同。黄骅位于河北平原,靠近渤海湾．属于滨海蝗区,蝗区植被以芦苇为主,是我国东亚飞蝗重点防治地区;平山位于河北和山西交界处,仍属于山区,蝗区位于岗南水库库区,属于滨湖蝗区,植被以稗草为主,并兼有玉米、豆类等农作物,为了保护岗南水库水质不受污染,该蝗区很少进行防治。对采自这两个蝗区东亚飞蝗的两种代谢酶：酯酶和谷胱甘肽S-转移酶进行了比较研究。用对氧磷、马拉氧磷、西维因及毒扁豆碱等4种抑制剂对这两个种群飞蝗的酯酶进行体外抑制实验,结果表明,这两个种群的大部分酯酶属于B-型。在雌性飞蝗中、用α-NA,αNB和β-NA3种酯酶底物测定酯酶活性,黄骅种群比平山种群的酯酶活性分别高1．63、1．66和1．70倍．雄性中则分别高1．12、1．41和1．27倍。对两个种群酯酶活性频率分布进行比较,黄骅种群中酯酶活性高的个体数远大于平山种群。两个种群酶活性的差异与马拉硫磷半致死剂量(LD50)的差异很相近,这提示酯酶活性的提高在东亚飞蝗对马拉硫磷的抗性中起一定的作用。酯酶活性频率分布显示出东亚飞蝗黄骅种群比平山种群具有较高的马拉硫磷抗性发展趋势．其抗性发展速度较平山种群快。然而,黄骅种群谷胱甘肽S-转移酶活性略低于平山种群,因此推测,谷胱甘肽S-转移酶活性与这两个东亚飞蝗种群对马拉硫磷的抗性无明显相关。     

东亚飞蝗耐高温能力及其体温调节行为

为明确东亚飞蝗Locusta migratoria manilensis的耐高温能力和体温调节行为, 采用高温饲养、提供辐射热源和风力等方法, 对东亚飞蝗各发育期的高温耐受能力、体温（body temperature, Tb）与环境温度（air temperature, Ta）和辐射温度（radiant temperature, Tr）的关系、飞蝗对辐射热的选择行为、体温升高速率以及辐射角度和风力对体温的影响进行了研究。结果表明: 东亚飞蝗44℃下饲养, LT90 最长为326.4 h; 50℃下, LT90可达20.6 h。无辐射热条件下, Tb随Ta的上升而升高, 当Ta升至32℃, 蝗虫出现体温调节行为; Ta以0.5℃/min速率上升时, 出现体温波动的个体数占试虫总数的53.7%, Tb平均波动温差为1.15℃, 平均波动时间为5.2 min, Tb平均波动起始温度为47.2℃, 成虫致死时间略长于若虫。有辐射热条件下, 随笼顶辐射温度的逐渐升高, 飞蝗趋向选择温度相对较低的笼底, 试虫体温调节较无辐射热条件下强; 辐射角度和风力均对飞蝗的体温有显著影响。结果显示东亚飞蝗对高温的耐受能力较强, 并且具有明显的体温调节行为, 可调节体温达到最佳生理状态。