Biological activities of extracts from traditionally used Nigerian plants against the European corn borer, Ostrinia nubilalis

Preliminary investigations with ethanolic (EtOH) extracts from five Nigerian plants show that extracts of Piper guineense Schum and Thonn (Piperaceae), Cedrela odorata L. (Meliaceae), Dennettia tripetala G. Baker (Annonaceae) and Aframomum melegueta (Rosch) K. Schum (Zingiberaceae) in artificial diets significantly reduced larval growth of European corn borer (ECB), Ostrinia nubilalis Hubner, at a concentration of 1000 ppm (0.1%). An extract of Xylopia aethiopica (Dunal) A. Rich (Annonaceae) was ineffective. When the extracts were subsequently incorporated into artificial diets at 300 ppm and offered to neaonates, larval mortality increased in the order A. melegueta (13%), D. tripetala (13%), P. guineense (27%), and C. odorata (48%). Larval and adult emergence periods increased with increasing concentration of P. guineense, C. odorata and D. tripetala indicating a toxic response. Nutritional indices for habituated third instar larvae with the two most promising plant extracts, P. guineense and C. odorata, showed that the efficiencies of conversion of digested food (ECD) was significantly reduced at 300 ppm suggesting a postdigestive toxicity of the extracts. P. guineense and C. odorata extracts show the best potential for development as botanical insecticides.     

Biology ofTrichogramma ostriniae (Hym.: trichogrammatidae) reared onOstrinia nubilalis (Lep.: pyralidae) and survey for additional hosts

Trichogramma ostriniae has been identified as a candidate for biological control ofOstrinia nubilalis. As little was known about the biology of this parasitoid when reared onO. nubilalis, we undertook experiments to quantify biological parameters important to mass-rearing and ase ofT. ostriniae. When reared continuously onO. nubilalis, femaleT. ostriniae on average lived 2.7 days and produced 24 progeny. Continuous access to honey resulted in a four-fold increase in longevity and fecundity and a significant increase in the percentage of females parasitizing eggs. Rates of fecundity and parasitism decreased with age of female. Likewise, emergence rates and percentage of female progeny decreased with age of parental female.T. ostriniae successfully parasitizedO. nubilalis eggs until the blackhead stage. Most parasitism of eggs and eclosion of adults occurred during the first half of photophase. Eggs of 13 Lepidopterans were parasitized byT. ostriniae. Eggs of the Noctuidae, Pyralidae, and Plutellidae experienced higher levels of parasitism than others tested.T. ostriniae appears to be similar to other species ofTrichogramma in several respects and does not possess any characteristics that limit its potential for mass rearing and use for augmentative biological control ofO. nubilalis.     

几种昆虫病毒交叉感染玉米螟的研究

银纹夜蛾NPV(P_aNPV)、柞蚕NPV(ApNPV)和赤松毛虫CPV(D_aCPV)可感染玉米螟。D_aCPV对玉米螟1龄幼虫的ID_(50)为5.9×10~5PIB/ml饲料,对幼虫的生长发育、蛹重、羽化率和成虫寿命有显著影响。D_aCPV主要侵染幼虫中肠柱状细胞,在细胞质中增殖;P_aNPV和A_pNPV主要侵染幼虫的体壁细胞和气管壁细胞。D_aCPV在玉米螟幼虫体内增殖后,多角体形态由正六角形变为锥形或四方形;成虫羽化时排出的蛹便可观察到多角体,病毒可传递给子代。利用其他昆虫病毒有防治玉米螟的可能性。     

转Bt基因抗虫玉米对亚洲玉米螟幼虫几种主要酶系活性的影响

研究了表达Cry1Ab杀虫蛋白的转Bt基因抗虫玉米对亚洲玉米螟Ostrinia furnacalis (uenée) 幼虫解毒酶、保护酶和中肠蛋白酶活性的影响,测定比较了取食转Bt基因玉米后幼虫体内α-乙酸萘酯酶、乙酰胆碱酯酶、谷胱甘肽S-转移酶、过氧化氢酶、超氧化物歧化酶、中肠总蛋白酶、类胰蛋白酶和类胰凝乳蛋白酶的活力。结果表明,取食转Bt基因玉米48 h后亚洲玉米螟幼虫体内的α-乙酸萘酯酶、谷胱甘肽S转移酶活力明显低于对照;而乙酰胆碱酯酶活力显著高于对照,在取食48 h、60 h和72 h的活力分别是对照的2.00、1.50和2.50倍。保护酶系、中肠总蛋白酶、弱碱性类胰蛋白酶和类胰凝乳蛋白酶的活性在取食48 h后明显受到抑制;但强碱性类胰蛋白酶的活性显著高于对照,取食48 h、60 h和72 h的活力分别是对照的4.00、1.67和1.33倍。乙酰胆碱酯酶和强碱性类胰蛋白酶可能与亚洲玉米螟对Bt的抗性有关。     

‘Becoming a species by becoming a pest’ or how two maize pests of the genus Ostrinia possibly evolved through parallel ecological speciation events

New agricultural pest species attacking introduced crops may evolve from pre‐existing local herbivores by ecological speciation, thereby becoming a species by becoming a pest. We compare the evolutionary pathways by which two maize pests (the Asian and the European corn borers, ACB and ECB) in the genus Ostrinia (Lepidoptera, Crambidae) probably diverged from an ancestral species close to the current Adzuki bean borer (ABB). We typed larval Ostrinia populations collected on maize and dicotyledons across China and eastern Siberia, at microsatellite and mitochondrial loci. We found only two clusters: one on maize (as expected) and a single one on dicotyledons despite differences in male mid‐tibia morphology, suggesting that all individuals from dicotyledons belonged to the ABB. We found evidence for migrants and hybrids on both host plant types. Hybrids suggest that field reproductive isolation is incomplete between ACB and ABB. Interestingly, a few individuals with an ‘ABB‐like’ microsatellite profile collected on dicotyledons had ‘ACB’ mtDNA rather than ‘ABB‐like’ mtDNA, whereas the reverse was never found on maize. This suggests asymmetrical gene flow directed from the ACB towards the ABB. Hybrids and backcrosses in all directions were obtained in no‐choice tests. In laboratory conditions, they survived as well as parental strain individuals. In Xinjiang, we found ACB and ECB in sympatry, but no hybrids. Altogether, our results suggest that reproductive isolation between ACB and ABB is incomplete and mostly prezygotic. This points to ecological speciation as a possible evolutionary scenario, as previously found for ECB and ABB in Europe.     

重金属 Ni2+ 对亚洲玉米螟生长发育和生殖行为的影响

【目的】探索农田重金属Ni²⁺污染对植食性昆虫潜在的影响。【方法】在人工饲料中添加不同浓度（1, 5, 10, 15和20 mg/kg）的重金属Ni²⁺,以不添加重金属的人工饲料为对照,实验室条件下饲养亚洲玉米螟 Ostrinia furnacalis (Guenée)初孵幼虫,系统观察其各项生长发育和生殖行为指标参数。【结果】Ni ²⁺对亚洲玉米螟幼虫期、蛹期、化蛹率和羽化率有抑制作用;对亚洲玉米螟雌蛹重有促进作用,但随Ni²⁺浓度的升高而逐渐减弱;低浓度Ni²⁺（1~10 mg/kg）对雄蛹重有促进作用,高浓度Ni²⁺（15~20 mg/kg）对雄蛹重有抑制作用。随着Ni²⁺浓度的增加,亚洲玉米螟雌蛾平均求偶持续时间逐渐减小;1 mg/kg Ni²⁺浓度下雌蛾求偶率及求偶高峰期出现的时间与对照组基本一致,其余4个Ni²⁺浓度都对雌蛾求偶行为产生影响且表现为求偶高峰期出现的时间提前,最高求偶率均小于100%。5 mg/kg Ni²⁺对亚洲玉米螟雄蛾定向行为有促进作用,其余浓度则表现为抑制作用。Ni²⁺对亚洲玉米螟雌蛾的产卵量和卵孵化率均产生了显著的抑制作用。【结论】重金属Ni²⁺对亚洲玉米螟的生长发育和生殖行为产生了影响。     

Predation risk and mating behavior: the responses of moths to bat-like ultrasound

In the presence of predators, animals may reduce or alter theirmating activities. There has been little experimental studyof whether mating behavior varies with the level of predationrisk. Two species of moths, Pseudaletia unipuncta (Noctuidae)and Ostrinia nubilalis (Pyralidae), significantly reduced theirmate-seeking behavior under high levels of simulated predationrisk. Male moths aborted upwind flight in a pheromone plume,and females stopped releasing pheromone in response to soundssimulating the echolocation calls of bats. For O. nubilalis,but not for P. unipuncta, the response varied significantlywith the level of predation risk. Interspecific differencesin behavioral responses likely reflect differences in physiologicalauditory sensitivity and/or behavioral thresholds. Female behavioralresponses to sounds simulating the calls of bats that gleantheir prey from surfaces were significantly weaker than theirresponses to sounds resembling the calls of aerially hawkingbats; these results support the neurophysiological data thatthe calls of gleaning bats are relatively inaudible to moths.This study indicates that some animals can modify their reproductiveactivities in response to auditory cues from predators.     

Orientation of European corn borer first instar larvae to synthetic green leaf volatiles

European corn borer (ECB) neonate larvae are capable of orienting towards maize odours and of avoiding spinach odours. We previously reported that maize odours’ attraction was dependent on the stimulus regime. This led us to propose that maize odours could have a repellent or attractive effect depending on their concentration. In this work, we tested this hypothesis by evaluating attraction or avoidance of neonate ECB larvae to four concentrations of each of six single green leaf volatiles (GLVs); these are commonly found in maize and other plants. We found a dose‐dependent effect for all of these GLVs with the exception of 1‐hexyl acetate, which did not elicit any orientation behaviour over the range of concentrations tested. These five GLVs were repellent at high concentrations, while two of them were attractive at a lower concentration. These observations indicate for the first time that plant odours induce different behaviours in ECB neonate larvae depending not only on their chemical identity but also their concentration.     

中国亚洲玉米螟发育历期的地理变异

广布种昆虫可调节其生活史以适应栖息地的条件变化,如可以通过调节自身的生长发育和繁殖期,使其发生与栖息地的物候(如食料、气温和降雨等)同步,这对昆虫在栖息地的繁衍具有十分重要的意义。亚洲玉米螟Ostrinia furnacalis为玉米主要害虫,在中国从南到北都有分布,栖息地气候也不同,不同地理种群生活史发生了分化,如化性、临界光周期、滞育后羽化时间、体重和体型、繁殖力和抗寒力等均不同。然而该虫发育历期的地理变异尚未见系统报道。为此,详细比较了来自5个亚洲玉米螟不同地理种群即广西阳朔(YS)、江西南昌(NC)、山东泰安(TA)、河北廊坊(LF)和黑龙江哈尔滨(HEB)在20—31℃下卵、幼虫、蛹发育历期及其与栖息地纬度的关系。结果表明:不同温度下的不同地理种群的卵期不存在显著差异,在20、22和25℃下,卵期从南到北稍有延长,卵期与其栖息地纬度呈正相关;但在28℃下,不同地理种群的卵期基本相等,与纬度相关性不显著。在31℃下,不同地理种群的幼虫期不存在显著差异,而在其他温度下,不同地理种群的幼虫期存在显著差异;在22、25和28℃下,幼虫期与其栖息地纬度呈正相关,而在20和31℃下,幼虫期与其栖息地纬度呈负相关,在20、22和25℃下,最北的哈尔滨种群的幼虫期变幅不大,而其他4个种群的幼虫期随着温度的升高明显缩短。各地理种群20℃下的雌蛹、28℃下的雄蛹和31℃下的雌雄蛹期差异均不显著,其他雌或雄蛹期差异显著;各温度下的雌雄蛹期与其栖息地纬度存在正相关关系。这些研究结果揭示了广布种昆虫可以调节其自身发育历期以适应栖息地环境条件。     

Effect of cold acclimation on the antioxidant defense system of two larval lepidoptera (noctuidae)

Activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GR), glutathione-S-transferase (GST), as well as total glutathione (tGSH) concentration were analyzed in the hemolymph and fat body of the European corn borer Ostrinia nubilalis Hubn. and the Mediterranean borer Sesamia cretica Led. (Lepidoptera, Noctuidae). Controls were maintained at 8°C while experimental groups of larvae were exposed to –3°C for ten days and then to –12°C for 23 days (only for Ostrinia). Cold exposure significantly increased fat body SOD, GR, and GST activities of Ostrinia larvae. Only GST activity and tGSH levels increased significantly in Ostrinia larval hemolymph on cold exposure. In Sesamia larvae after cold exposure, hemolymph CAT activity was significantly lower, while fat body tGSH increased. The antioxidant defense systems of these two species show differences, probably influenced by their respective cold-hardiness metabolism. According to its antioxidant profile, the response of Ostrinia suggests a significant physiological alteration in its metabolism during cold exposure, indicating a compensatory mechanism. By contrast this is not evident in Sesamia.Arch. Insect Biochem. Physiol. 36:1–10, 1997. © 1997 Wiley-Liss, Inc.