Field and laboratory biology of the stem-feeding beetle Thamnurgus euphorbiae (Küster) (Col., Scolytidae) in Italy, a potential biological control candidate of leafy spurge in the USA and Canada

Thamnurgus euphorbiae overwinters as adults in dry stems of Euphorbia characias until the end of March before exiting through circular holes cut with their mandibles. Females and males appeared in the field at the same time, and the first pairs were observed on 28 March on new stems of E. characias having the open‐flower at the beginning of its development. Throughout the rest of April it was possible to find and collect the fairly abundant adults. Mating occurs on new stems of the host plant and females walk up towards the top of the stem and start to mine the centre of it in order to penetrate. Oviposition occurs in new stems and eggs are laid singly along the interior of the stem; females laid 35–85 eggs. Upon hatching, larvae started feeding on vascular bundles and the inner cortex. There are three larval instars, and pupation occurred in the stem of the host plant; this insect is univoltine. Thamnurgus euphorbiae has been accepted by the Technical Advisory Group for Biological Control Agents of Weeds for release as a biological control agent of leafy spurge in the US. Prior to this study the biology of T. euphorbiae was unknown.     

Food‐availability dependent premature metamorphosis in the bean blister beetle Epicauta gorhami (Coleoptera: Meloidae), a hypermetamorphic insect that feeds on grasshopper eggs in the larval stage

Larvae of the bean blister beetle, Epicauta gorhami, feed on only grasshopper eggs and undergo hypermetamorphosis with pseudopupal diapause in the fifth instar. Whether E. gorhami larvae enter pseudopupal diapause or pupate directly from the fourth instar is controlled by temperature and photoperiod. In nature, larvae are confronted with a significant variation in the availability of food, suggesting the possibility that feeding conditions may also affect the diapause incidence. Here, we addressed this issue by changing the feeding conditions in the fourth instar under conditions of 16 h light : 8 h dark (LD 16 : 8) at 25°C. Food deprivation reduced the length of instar and increased the tendency to pupate, leading to the early eclosion of a small adult. Even non‐feeding fourth‐instar larvae pupated. Regardless of the timing of food deprivation, the post‐feeding larval period was constant and equivalent to that of ad libitum‐fed larvae, suggesting that premature exhaustion of the food supply triggers the initiation of pupation. In agreement with these results, when larvae were fed on intact grasshopper egg pods of various sizes from four species, those that fed on smaller egg pods had a decreased tendency to pseudopupate (i.e., to enter diapause). Food‐deprived larvae showed a clearer photoperiodic response and had a shorter critical day‐length. Thus, in E. gorhami, feeding conditions do not affect pupation success, but do affect the tendency to pupate or pseudopupate. This is the first report of the occurrence of premature pupation in carnivorous insects. We discuss our findings in the context of the natural history and behavioral ecology of E. gorhami.     

Critical periods in the life cycle and the effects of a severe spate vary markedly between four species of elmid beetles in a small stream

1. The chief objectives were: (i) to describe quantitatively the life cycles of four species of Elmidae, Elmis aenea, Esolus parallelepipedus, Oulimnius tuberculatus and Limnius volkmari; (ii) to use life tables to identify critical periods for survival in the life cycle of each species; (iii) to evaluate the immediate and longer‐term effects of a severe spate on densities of the four species. Monthly samples were taken over 63 months at two contrasting sites in a small stream: one in a deep section with macrophytes abundant, and the other in a shallow stony section. 2. There were five larval instars for O. tuberculatus, seven for L. volkmari and six for the other two species. The life cycle of each species took 1 year from egg hatching (chiefly in June for E. aenea and O. tuberculatus, and July for the other species) to pupation in the stream bank and a further year before the adults in the stream matured and laid their eggs. Mature adults were present in most months, but were rare or absent in January and February and attained maximum densities in April for O. tuberculatus and May for the other species. 3. Laboratory experiments provided data on egg hatching and pupation periods and the number of eggs laid per female. Life tables compared maximum numbers per square metre for key life‐stages. Within each species, mortality rates between adjacent life‐stages were fairly constant among six cohorts and between sites, in spite of large differences in numbers. The only exception for all species was the high adult, but not larval, mortality during a severe spate. 4. Standardised life tables, starting with 1000 eggs, identified key life‐stages with the highest mortality, namely the early life‐stages for E. aenea (36% mortality), start of the overwintering period to pupation for O. tuberculatus (41%) and L. volkmari (51%), start of pupation to the maximum number of immature adults for E. parallelepipedus (41%) and between the maximum numbers of immature and mature adults for O. tuberculatus (41%). Therefore, critical periods for survival in the life cycle differed between species, presumably because of their different ecological requirements. Similarly, the effects of the spate on adult mortality, and hence egg production, varied between species, being most severe and long‐term for E. aenea and O. tuberculatus, less severe for E. parallelepipedus and least severe with a rapid recovery for L. volkmari. Possible reasons for these discrepancies are discussed, but more data are required on the food and microhabitat requirements of the elmids before satisfactory explanations can be found.     

中国真片叶蜂属(膜翅目,叶蜂科)四新种

记述采自中国河南的真片叶蜂属4新种:短室真片叶蜂Eutomostethus brevicellus Wei et Niu,sp.nov.,狭突真片叶蜂Eutomostethus lineituberculus Wei et Niu,sp.nov.,白腹真片叶蜂Eutomostethus albiventralinus Wei et Niu,sp.nov.和假亮真片叶蜂Eutomostethus pseudometallicus Wei et Niu,sp.nov..新种模式标本保存于湖南长沙中南林业科技大学昆虫模式标本室.     

Optimization of breeding output for larval stage of Anopheles gambiae (Diptera: Culicidae): prospects for the creation and maintenance of laboratory colony from wild isolates

Domesticating anopheline species from wild isolates provides an important laboratory tool but requires detailed knowledge of their natural biology and ecology, especially the natural breeding habitats of immature stages. The aim of this study was to determine the optimal values of some parameters of Anopheles gambiae larval development, so as to design a standard rearing protocol of highland isolates, which would ensure: the biggest fourth instars, the highest pupae productivity, the shortest duration of the larval stage and the best synchronization of pupation. The density of larvae, the size of breeding water and the quantity of food supplied were tested for their effect on larval growth. Moreover, three cheap foodstuffs were selected and tested for their capability to improve the breeding yield versus TetraMin? as the standard control. The larval density was a very sensitive parameter. Its optimal value, which was found to be ≈1?cm-2 surface area, yielded a daily pupation peak of 38.7% on day 8 post-oviposition, and a global pupae productivity of 78.7% over a duration range of three days. Anopheles gambiae's larval growth, survival and developmental synchronization were density-dependent, and this species responded to overcrowding by producing smaller fourth instars and fewer pupae, over elongated immature lifetime and duration range of pupae occurrence, as a consequence of intraspecific competition. While shallow breeding waters (<3?cm) produced a higher number of pupae than deeper ones, no effect of the breeding habitat's absolute surface area on larval development was observed. Increasing the daily food supply improved the pupae productivity but also boosted the water pollution level (which was assessed by the biological oxygen demand (BOD) and the chemical oxygen demand (COD)) up to a limit depending on the food quality, above which a rapid increase in larval mortality was recorded. The food quality that could substitute the manufactured baby fish food was obtained with weighed mixture of 1 wheat+1 shrimp+2 fish. On establishing an anopheline mosquito colony in the laboratory, special care should be taken to design and maintain the appropriate optimal values of larval density, water depth, daily diet quantity and nutritional quality.     

Juvenile hormone-mediated termination of larval diapause in the bamboo borer, Omphisa fuscidentalis

Larvae of the bamboo borer, Omphisa fuscidentalis are in diapause for more than nine months (Singtripop, T., Wanichaneewa, S., Tsuzuki, S., Sakurai, S. 1999. Larval growth and diapause in a tropical moth, Omphisa fuscidentalis Hampson. Zool. Sci. 16, 725-733). To examine the endocrine mechanisms underlying this larval diapause, we assayed the responsiveness of the diapausing larvae to 20-hydroxyecdysone (20E) and a juvenile hormone analogue (JHA: S-methoprene). 20E injection caused the larvae to halt movement, followed by deposition of a pupal cuticle. Topical application of JHA induced pupation in a dose-dependent manner. JHA also induced pupation of the larvae whose brains were removed before JHA application. In those larvae, the prothoracic glands became active and competent to respond to brain extracts within seven days after JHA treatment, and the hemolymph ecdysteroid concentration began to increase 12 days after JHA application. These results indicate that JHA stimulates the prothoracic glands of diapausing Omphisa larvae, terminating larval diapause, in contrast with previous findings that JH inhibits the brain-prothoracic gland axis and thus maintains the larval diapause. Current results therefore suggest a novel regulatory mechanism for larval diapause in this species.     

The oviposition sites of five leafhopper species (Horn. Auchenorrhyncha) on Holcus mollis and H.lanatus

Abstract. 1. A study was made of the oviposition sites of five leafhopper species Diplocolenus abdominalis, Recilia coronifera, Errastunus ocellaris, Elymana sulphurella (Cicadellidae) and Dicranotropic hamata (Delphacidae) on the grasses Holcus mollis and H.lanatus.
2. Experiments were made in the laboratory, each insect species being provided simultaneously with a complete plant of both Holcus species.
3. Distribution of eggs within the leaf sheath and leaf blade, and their height above ground-level, were recorded.
4. The presence and size of egg groups were noted, as well as the angle of eggs to the longitudinal axis of the leaf.
5. On the basis of comparison of the vertical distribution of the eggs with availability of plant tissues, the five species can be divided into three groups: (a) D.abdominalis and R.coronifera , (b) D.hamata and E.ocellaris , (c) E.sulphurella. Species within a group, i.e. with similar distributions of eggs, have other features separating their oviposition sites.     

The Life History and Host Range of Charidotis pygmaea (Col.: Chrysomelidae), a Biological Control Agent for Lantana montevidensis (Verbenaceae)

The life cycle and host range of Charidotis pygmaea Klug were investigated to assess its suitability for release as a biological control agent for Lantana camara L. and L. montevidensis (Sprengel) Briquet. Adults fed and deposited eggs on the underside of leaves of both species. They generally laid fewer eggs in the dry winter months when lantana yellows or drops its leaves. Larvae fed on the upper leaf surface and pupation occurred on the leaves or stems. Development from egg to adult took approximately 50 days. Survival to the adult stage was greater, and the development time was shorter on L. montevidensis than on all varieties of L. camara tested, suggesting that the agent would be ineffective against L. camara. Forty-two plant species were tested to determine host specificity in choice oviposition and larval feeding trials. These demonstrated that C. pygmaea did not pose a threat to non-target species. Consequently, C. pygmaea was approved for release in Australia and through its ability to survive the dry season, should assist in the control of L. montevidensis.     

蚕豆象的生物学特性

在武昌,蚕豆象Bruchus rufimanus Boheman每年发生一代,以成虫越冬。成虫必须取食蚕豆花后才能正常交配和产卵。4月为交配盛期。4月中、下旬为产卵盛期,最喜欢把卵产到生长已有1l—20天的嫩蚕豆荚上,但不在豌豆荚上产卵。产卵历期约为9天。4月下旬至5月上旬为孵化盛期。幼虫共四龄,在豆粒内的死亡率随着单个豆粒上侵入孔的增多而增高。8月为化蛹盛期,8月中旬到9月上旬为羽化盛期。羽化出的成虫绝大部分藏在豆粒内越冬。从卵发育到成虫羽化约需120天。成虫寿命一般为212天,最长达295天,但不能度过两个冬季。     

Life history and larval morphology of Eurhinus magnificus Gyllenhal (Coleoptera: Curculionidae), a new weevil to the United States

Eurhinus magnificus Gyllenhal has been collected in south Florida, presumably introduced through trade with countries in its native range. Very little information has been published on the biology or taxonomy of this insect. We conducted studies to investigate various aspects of its life history and host plant associations. The pre-imaginal life stages of E. magnificus are described for the first time. Dimensions of the adult, egg, larval, and pupal stages are also provided; head capsule measurement revealed five larval instars. All life stages of E. magnificus were collected at several sites in Broward and Miami-Dade counties from the host plant Cissus verticillata (L.) Nicolson & Jarvis (Vitaceae). Eggs were laid singly within the succulent, young subterminal portion of the host plant stem, one or two occurring between two nodes. Gall formation was apparent by the first to third instar and continued to increase in size until pupation which occurred within the gall. Predators and pathogens appeared to be responsible for considerable mortality in the field; there was no evidence of parasitism of any of the life stages. Greenhouse studies were undertaken to determine E. magnificus development time and host specificity. Adult weevils attacked grape cultivars (Vitis spp.) and feeding opened the stems to fungal agents but no physical evidence of larval development was apparent on grapes.     

OBSERVATIONS ON THE BIOLOGY OF CORYMBITES CUPREUS F. (COLEOPTERA, ELATERIDAE)

The life history of Corymbites cupreus F. is described, and its economic importance is assessed from field observations and laboratory experiments. The females are on the wing in May and June, egg-laying takes place in June and the incubation period is about 34 days. The larval stage probably occupies 5 years under field conditions and pupation occurs towards the end of July or beginning of August. The imagines emerge in about 21 days, but they do not always remain in their earthen pupal cells until the following spring as do several other Elaterid species. The larvae feed principally on the roots and underground stems of plants, but they can exist on decayed organic matter in the soil. Individually they are far more injurious to potatoes, wheat, oats, barley and other cultivated crops than those of either Agriotes spp. or Athous niger, but because they are restricted to comparatively high altitudes, they are seldom pests of major importance. Birds and cara-bid larvae readily feed on them and they are also subject to attack by a hymeno-pteran parasite and the fungi, Metarrhizium anisopliae (Metsch) Sor. and Synglio-cladium cleoni (Wize) Petch. All attempts to obtain control of the larvae by the use of these fungi failed.     

Ant queens adjust egg fertilization to benefit from both sexual and asexual reproduction

An enduring problem in evolutionary biology is the near ubiquity of sexual reproduction despite the inherent cost of transmitting only half the parent's genes to progeny. Queens of some ant species circumvent this cost by using selectively both sexual reproduction and parthenogenesis: workers arise from fertilized eggs, while new queens are produced by parthenogenesis. We show that queens of the ant Cataglyphis cursor maximize the transmission rate of their genes by regulating the proportion of fertilized and parthenogenetic eggs laid over time. Parthenogenetic offspring are produced in early spring, when workers raise the brood into sexuals. After the mating period, queens lay mostly fertilized eggs that will be reared as the non-reproductive caste.     

Novel microsatellite markers suggest the mechanism of parthenogenesis in Extatosoma tiaratum is automixis with terminal fusion

Parthenogenetic reproduction is taxonomically widespread and occurs through various cytological mechanisms, which have different impact on the genetic variation of the offspring. Extatosoma tiaratum is a facultatively parthenogenetic Australian insect (Phasmatodea), in which females oviposit continuously throughout their adult lifespan irrespective of mating. Fertilized eggs produce sons and daughters through sexual reproduction and unfertilized eggs produce female offspring via parthenogenesis. Here, we developed novel microsatellite markers for E. tiaratum and characterized them by genotyping individuals from a natural population. We then used the microsatellite markers to infer the cytological mechanism of parthenogenesis in this species. We found evidence suggesting parthenogenesis in E. tiaratum occurs through automixis with terminal fusion, resulting in substantial loss of microsatellite heterozygosity in the offspring. Loss of microsatellite heterozygosity may be associated with loss of heterozygosity in fitness related loci. The mechanism of parthenogenetic reproduction can therefore affect fitness outcomes and needs to be considered when comparing costs and benefits of sex versus parthenogenesis.     

GAMETIC INCOMPATIBILITY BETWEEN SPECIES OF THE SEA URCHIN ECHINOMETRA ON THE TWO SIDES OF THE ISTHMUS OF PANAMA

The Pliocene rise of the Central American Isthmus has resulted in numerous “geminate pairs,” i.e., closely related species, one on each coast. Such species pairs can provide information on the evolution of isolating mechanisms in allopatry and on the relationship between genetic divergence and reproductive isolation in populations separated at a known time. The sea urchin genus Echinometra has one species, E. vanbrunti, in the eastern Pacific, and two, E. lucunter and E. viridis, in the Caribbean. E. viridis is morphologically distinct from the other two species, leading to the conclusion that E. lucunter and E. vanbrunti constitute a geminate pair. Allozyme data, on the other hand, place the speciation event of the two currently sympatric species after the rise of the Isthmus. We report fertilization experiments between the gametes of the three species performed to determine degree of reproductive isolation. Crosses between E. viridis and E. vanbrunti produce rates of fertilization almost equal to those manifested in homogamic crosses. Sperm of E. lucunter can fertilize eggs of the other two species, but few of its eggs permit fertilization by heterospecific sperm. Contrary to the predictions of the “speciation by reinforcement” hypothesis, degree of incompatibility between the allopatric E. lucunter and E. vanbrunti is higher than between the sympatric E. lucunter and E. viridis. Despite the incomplete and unidirectional nature of their gametic isolation, E. lucunter and E. viridis maintain their genetic integrities. Consideration of the likely phylogenetic relationships between the three species suggests that incompatibility of E. lucunter eggs with heterospecific sperm has evolved in the last 3.5 million years, after the rise of the Isthmus. There is no correlation between genetic divergence and strength of reproductive isolation, either within Echinometra, or among the geminate species pairs of echinoids that have been studied to date. Because recognition between echinoid gametes depends on the chemical compositions of a sperm protein and an egg glycoprotein, the appearance of gametic isolation would require only the fixation of a few mutations in each population on either side of a geographic barrier and could be independent of any other kind of genetic divergence. Thus, in animals with external fertilization, speciation need not be accompanied by major genomic reorganization.     

不同生态型的喜旱莲子草对莲草直胸跳甲化蛹能力的影响

 喜旱莲子草(Alternanthera philoxeroides)是一种水陆两栖的外来杂草,我国1986年从美国引进了该草的专食性天敌莲草直胸跳甲(Agasicles hygrophila)进行生物防治。该天敌的化蛹能力受喜旱莲子草不同生态型的影响,从而影响到其生物防治的效果。从形态解剖的角度结合天敌和寄主植物的田间生理生态学研究了其机理。结果表明：水生型喜旱莲子草无次生结构,而陆生型则具紧密的次生结构和丰富的晶体;不同生态型的喜旱莲子草茎秆形态和结构特征有显著差异,同一生态型草不同位置结构特征也存在显著差异。主成分分析和聚类分析结果表明当λ=3.56时,不同生态型不同节间位置可分为3类,这3类正好可解释田间喜旱莲子草受控制的情况。相关分析表明莲草直胸跳甲的化蛹率与茎秆节间长、茎秆外直径、髓腔成简单正相关,与皮层薄壁细胞厚度和密度、维管束厚度及髓腔薄壁细胞的厚度成简单负相关;用逐步回归建立了化蛹率与形态和解剖结构特性的模型（y=1.533　2-0.248　3x3-0.051　2x4-1.634　9x5-0.957　7x6R2=0.999　9）,表明茎秆直径大小不是影响莲草直胸跳甲化蛹能力的最重要因子,主要原因为维管柱的厚度,其次髓部薄壁细胞厚度、皮层密度和皮层厚度也不同程度影响了莲草直胸跳甲的化蛹能力。从解剖学角度解释了莲草直胸跳甲对不同生态型喜旱莲子草控制作用的机理：对水生型喜旱莲子草有良好控制效果,而对陆生的中间型能起到一定抑制作用,对陆生的旱生型基本无控制作用。     

The reproductive cycle of thelytokous colonies of Cerapachys biroi Forel (Formicidae,Cerapachyinae)

Summary: The reproductive cycle of thelytokous colonies of Cerapachys biroi was investigated in laboratory conditions. It included several stages, the duration of which was assessed by direct observation on experimental nests set up by fission of natural, queenless, colonies. The results show that two phases of adult activity alternated while cohorts of brood developed synchronously. During the statary phase, virgin workers laid diploid eggs simultaneously but no foraging activity was observed until the following phase which began after the callow workers of the previous brood cohort emerged and the eggs hatched. During this foraging phase, workers explored intensively for food while larvae matured synchronously. Biometrical measures allowed to determine that three larval instars occurred in this species. While larvae started pupation, workers stopped to forage and the next statary phase took place, during which a new cohort of eggs was laid and pupae matured. This repeated phasic reproductive cycle where adult activity and development of the brood are synchronised reminds that of true army ants (subfamily Ecitoninae), which brings new arguments in favour of a filiation between both groups.     

Aedes aegypti midgut remodeling during metamorphosis

The Aedes aegypti midgut is restructured during metamorphosis; its epithelium is renewed by replacing the digestive and endocrine cells through stem or regenerative cell differentiation. Shortly after pupation (white pupae) begins, the larval digestive cells are histolized and show signs of degeneration, such as autophagic vacuoles and disintegrating microvilli. Simultaneously, differentiating cells derived from larval stem cells form an electron-dense layer that is visible 24 h after pupation begins. Forty-eight hours after pupation onset, the differentiating cells yield an electron-lucent cytoplasm rich in microvilli and organelles. Dividing stem cells were observed in the fourth instar larvae and during the first 24 h of pupation, which suggests that stem cells proliferate at the end of the larval period and during pupation. This study discusses various aspects of the changes during midgut remodeling for pupating A. aegypti.     

平卧川牛漆甾酮对小菜蛾生长发育的影响(英文)

平卧川牛漆甾酮是紫背金盘中的主要植物蜕皮甾类 ,在筋骨草属植物中普遍存在。试验结果表明 ,用 5 0mg L平卧川牛漆甾酮处理小菜蛾卵 ,其孵化受到抑制 ,总孵化率为 94.7% ,显著低于对照的 1 0 0 %孵化。平卧川牛漆甾酮对幼虫具有弱的毒杀活性和良好的拒食活性 ,且与浓度相关。小菜蛾的生长发育也受平卧川牛漆甾酮的影响。用高于 5 0mg L浓度处理幼虫 ,其生长受抑及蛾的产卵量下降 ,而较低浓度处理则有利于幼虫生长 ,卵量提高。这种双重作用可能是由于平卧川牛漆甾酮的激素活性和拒食活性的作用结果 ,后者导致昆虫营养不良。处理幼虫后 ,试虫的化蛹和羽化受阻。小菜蛾对平卧川牛漆甾酮比 2 0 羟基蜕皮酮更敏感。     

中国云南松叶蜂科二新种一新组合记述：膜翅目：广腰亚目

在中国云南省发现松叶蜂科Ｄｉｐｒｏｎｉｄａｅ２新种,即钝齿吉松叶蜂Ｇｉｌｐｉｎｉａｈｅｂｅｄｅｎｔａｔａ新种和吴氏大松叶蜂Ｍａｃｒｏｄｉｐｒｉｏｎｗｕｉ新种。另一个记载于云南的种ＧｉｌｐｉｎｉａｄｉｓａＳｍｉｔｈ从吉松叶蜂属ＧｉｌｐｉｎｉａＢｅｎｓｏｎ移入小松叶蜂属ＭｉｃｒｏｄｉｐｒｉｏｎＥｎｓｌｉｎ,称迪萨小松叶蜂Ｍｉｃｒｏｄｉｐｒｉｏｎｄｉｓｕｓ（Ｓｍｉｔｈ）新组合。大松叶蜂属Ｍａｃｒｏｄｉｐ