Oviposition behaviour of the grasshopper Zonocerus variegatus

Abstract. 1. Long-term changes in the numbers of Zonocerus at oviposition sites reflect changes in the maturity of the general population.
2. Short-term changes in the numbers of Zonocerus at oviposition sites are associated partly with normal diurnal behaviour in which roosting occurs at night.
3. Immigration of Zonucems , particularly females, into the oviposition site occurs prior to periods of oviposition activity. Emigration follows oviposition.
4. The majority of Zonocerus move upwind into the oviposition site suggesting an odour and/or sound attraction.
5. Periods of intense oviposition activity follow heavy rainfall.     

Peripheral-zone treatments for plum curculio management: validation in commercial apple orchards

A field trial was conducted using an oil formulation of the entomopathogenic fungus, Metarhizium flavoviride Gams & Rozyspal (Deuteromycotina: Hyphomycetes), to control the variegated grasshopper, Zonocerus variegatus L. (Orthoptera: Pyrgomorphidae). The influence of dispersal and secondary pick-up from the spray residue on mortality was assessed by sampling insects from the treated plots at intervals and monitoring disease levels during subsequent incubation in the laboratory. The cumulative mortality curves showed the pathogen to be highly effective, even in samples taken 8 days after spraying. A model was developed to link the influence of mortality, incubation, secondary pick-up of spores and insect dispersal, on the shape of these cumulative mortality curves. The model proved useful for data received from an experiment using small plot sizes, where insect dispersal is a big problem. The spray residue had an important influence on overall insect mortality. The model also indicated a difference in speed of kill between field and laboratory samples, suggesting an incubation delay in the field.     

胚后发育期臭腹腺蝗中的血细胞种类

应用血球计数器统计了胚后发育期臭腹腺蝗Zonocerus variegatus中存在的血细胞类型和数目。从1龄幼虫至成虫的发育阶段中共观察到6种血细胞类型,即原血细胞 （PRS）、 浆血细胞 （PLS）、粒细胞 （GRS）、珠血细胞 （SPS）、绛色细胞（OES） 和adipohaemocytes （ADS）。不过,在1龄幼虫期未发现OES。在这6种血细胞中,PLS的总平均数最高,OES的总平均数最低。成虫期的血细胞数目显著高于其他发育阶段（P<0.05）,而1龄幼虫和2龄幼虫期的血细胞数目不存在显著差异（P>0.05）。     

Field Infection of Zonocerus variegatus following application of an oil‐based formulation of Metarhizium flavoviride conidia

Conidia of Metarhizium flavoviride grown in diphasic culture with sporulation on rice, were extracted in kerosene and formulated with peanut oil. The formulation led to high mortality when applied to field populations of Zonocerus variegatus; between 70 and 95% of insects in samples collected from the field 0, 3 or 7 days after spraying died. Sporulation of M. flavoviride was observed in 70–80% of the dead‐treated insects, which compares favourably with results obtained in laboratory bioassays. Many dead Z. variegatus, some with internal sporulation, were found in shaded niches and oviposition sites in the treated plots. No sporulation was observed in samples collected prior to application, and both sporulation and mortality differed significantly between control and treated plots. Some infections were observed in insects collected 16 and 23 days after treatment; these late infections may be a consequence of contact with spores surviving in the environment.     

Development of a model for evaluating the effects of environmental temperature and thermal behaviour on biological control of locusts and grasshoppers using pathogens

1 Recent years have seen an upsurge in locust and grasshopper populations in many parts of the world. Environmentally sustainable approaches to locust and grasshopper control may be possible through the use of biopesticides based on entomopathogenic fungi. Unfortunately, the performance of these biopesticides is highly variable with environmental temperature and host thermoregulatory behaviour critically determining the pattern and extent of mortality after applications. Here, we present a temperature‐dependent model that enables us to predict the field performance of Metarhizium anisopliae var. acridum, the key fungal pathogen used in locust biopesticides. 2 The model was constructed using mortality rate data generated across a range of temperatures in the laboratory and is driven by environmental temperature data linked through host body temperature models. 3 Model predictions were validated against empirical field data obtained for five species, Locustana pardalina, Oedaleus senegalensis, Zonocerus variegatus, Nomadacris septemfasciata and Chortoicetes terminifera. Mortality predictions were accurate to a 2‐day error in every 10 days. This level of resolution is satisfactory to guide operational use of the biopesticide. 4 The model was subsequently used for a prospective evaluation of the performance of M. anisopliae var. acridum against two additional pest species, Dociostaurus maroccanus and Calliptamus italicus in Spain. Results suggest that this pathogen would work reasonably well against these species as long as early instars are targeted. 5 The model could provide a useful tool to assist in interpreting effectiveness of control operations, develop improved application strategies to optimize the performance of the biopesticide and identify appropriate target species and environments.     

臭腹腺蝗（直翅目： 锥头蝗科）中肠内营养物-水分的流动和吸收

对臭腹腺蝗Zonocerus variegatus中肠内水分和营养物的流动和吸收进行了研究,以期确定其流动模式及在该虫对氰化氢适应方面的意义。对中肠细胞进行了组织切片观察;测定了K⁺, Na⁺和蛋白质沿中肠的浓度梯度,并观察了中肠对K⁺, Na⁺, Ca²⁺, Mg²⁺和甲基蓝的通透性。结果表明,中肠（胃和胃盲囊）组织上结构相似,均由具有纹状边缘的柱状细胞构成。营养物质在中肠不同部分的浓度不同。测试物在整个中肠中流动,中肠各段均参与了食物和水分的吸收。臭腹腺蝗肠内没有像大多数直翅目昆虫那样自后肠的液流逆向流动。肠溶物的单向流动可以防止有毒物质的积累,使臭腹腺蝗成功耐受木薯叶中的氰化氢。     

Effect of 13 single and eight mixed host plant diets on survival, post-embryonic development and morphology of variegated grasshopper in laboratory

Zonocerus variegatus (Orthoptera: Pyrgomorphidae) is known as an agricultural pest in West and Central Africa. In this study, the effects of 13 single and eight mixed host plant diets on the survival, post-embryonic development and morphology of Z. variegatus in the laboratory were investigated. In each cage, 20 one-day larvae were provided with these diets and their survival monitored every two days, from August 2000 to September 2002, until all individuals died. Results showed that the number of larval stages varied from six to eight according to the diet. Six larval stages were most frequent. Development to the adult stage (complete development) was only noted with 52% of diets. All the mixed host plant diets induced complete development of Z. variegatus except that of Cajanus cajan + Synedrella nodiflora + Chromolaena odorata . Complete development was observed with four single host plant diets: Lablab purpurea , C. cajan , Manihot esculenta and S. nodiflora . Compared to leguminous species and Asteraceae, M. esculenta (Euphorbiaceae) was the species that resulted in the highest level of survival and development of Z. variegatus . Chromolaena odorata and S. nodiflora (Asteraceae) induced late appearance of the different Z. variegatus nymphal instars and the appearance time was shorter on legumes. The supernumerary stage 7 has the same color as the larva in stages 1–6, but this larva was significantly larger than stage 6 and smaller than the adult stage. These results indicate that legumes for short fallows affected the survival and post-embryonic development of Z . variegatus in the laboratory.     

臭腹腺蝗（直翅目：锥头蝗科）胃盲囊的异速生长和功能特性

通过对臭腹腺蝗Zonocerus variegatus（直翅目：锥头蝗科）6个若虫期及成虫期主消化道和胃盲囊分段进行解剖和测量,对其胃盲囊的异速生长和功能特性进行了研究。结果表明,胃盲囊和主消化道的生长是不同速的。胃盲囊前段较后段生长速率更高,但两者生长速率显著相关。消化道和胃盲囊的平均长度亦显著相关。随年龄增长,消化道的生长速率降低,而胃盲囊的生长速率上升。与胃盲囊前段功能相同,胃盲囊后段亦具有消化和吸收功能,被认为能在营养缺乏的旱季起到增加肠胃吸收面的功能。     

臭腹腺蝗肠道中共存的淀粉和纤维素消化酶的纯化、动力学和抑制研究（英文）

【目的】本研究旨在了解臭腹腺蝗 Zonocerus variegatus 中碳水化合物的消化。【方法】依次通过CM-Sepharose CL-6B 阳离子交换、QAE Sephadex A-50阴离子交换以及Sephadex G-100凝胶过滤,对臭腹腺蝗中肠的酶粗提取液（其中α-淀粉酶和纤维素酶的比活性分别为283±1.72 U/mg和 17±0.83 U/mg）进行了纯化。最后通过层析将共存的酶分离成α-淀粉酶和纤维素酶。【结果】这两种酶都是单体,α-淀粉酶分子量为38 kDa ,纤维素酶分子量为21 kDa。α-淀粉酶对淀粉的K_m 值为 13.8±1.29 mg/mL,V_max为3 883±52.25 U/mg pro;而纤维素酶对羧甲基纤维素底物的 K_m 值为5.03±0.57 mg/mL ,V_max为433.00±5.24 U/mg pro 。臭腹腺蝗α-淀粉酶能以不同的效率水解原淀粉,纤维素酶也能不同程度水解各种纤维材料。α-淀粉酶的水解活性在pH 6和40℃下最高,而纤维素酶的水解高活性在pH 9和45℃下最高。【结论】 从番木瓜 Carica papaya 种子中分离到蛋白类抑制剂,发现它们是这两种酶的有效抑制剂,说明这些蛋白抑制剂(CpAI和 CpCI)如果在害虫取食的作物上过量表达,则可能有利于害虫防治。尽管纤维类和淀粉类物质可能都显著提供该害虫的能量需求,但是动力学分析表明臭腹腺蝗更偏向于淀粉类食物。     

Diet of Zonocerus variegatus (Linné, 1758) (Orth., Acrididae) in cassava fields in Bénin

Abstract:  This paper presents the results of a study on the diet of Zonocerus variegatus in cassava agro-ecosystems at Allada, south Benin. The diet was determined by the analysis of plant fragments in the faeces of insects sampled in the fields. The grasshoppers studied consumed 21 plant species among the 81 found in the fields. Cassava, maize, Mallotus oppositifolius and Chromolaena odorata were the major food plants for Z. variegatus in this system. The presence of Z. variegatus in different fields was observed depending on the season and the presence of certain plant species. There was no relationship between plant frequency in the diet and in the field. Cassava was the preferred food resource for mature nymphs and adults. During the dry season, young nymphs stayed near the hatching sites and where good food resources were available. At this time, the grasshoppers were present in a field where cassava was not abundant but where maize and weeds were available. During the dry season, Z. variegatus had a broader diet than during the wet season. This contradicts the current hypothesis that the water content of plants and the floral diversity determines food preference. The dry season is also the time when C. odorata leaves were found in the faeces of both adults and nymphs. These observations made in West Africa are similar to those made in Central Africa, particularly for the number of plant species found in the faeces, 21 (26% of all plant species found in the fields) in Bénin and 17 (23%) in the Congo. The increase of the sample size and the great differences between the ecoregional situation of the study sites do not substantially change the number of plant species included in the diets. In the area covered by this study, C. odorata is not the major substitute for cassava during the dry season, although it remains a major food source and an especially visible food resource.