光谱和光强度对棕榈蓟马雌成虫行为反应的影响

室内研究了光谱、光强度对棕榈蓟马雌成虫的趋、避光行为的影响。结果显示:在340—605 nm波谱内棕榈蓟马雌成虫对14个单色光刺激的趋光行为反应为多峰型。其中蓝光483 nm处峰最高,趋光反应率达34.96%,其次为绿光498—524 nm、562—582 nm、紫外光340 nm处;其避光行为反应共有3个峰,其中紫外光380 nm处最高,避光率18.08%,另外2个峰分别在橙光605 nm、紫光420 nm处。在趋光率较高的单色光(340、483、524、582 nm)和避光率较高的单色光(380、605 nm)以及白光刺激下,棕榈蓟马雌成虫的趋光率随光强增强的增强而提高,而避光率则随着光强的增强而降低;光强最弱时仍均有一定趋光率,最强时均未出现高端平台。因此:棕榈蓟马雌成虫对不同单色光具有明显的选择性,光谱和光强度对其趋光行为和避光行为有较大影响,光强度的影响作用与波长因素有关。     

The <Emphasis Type="Italic">Tribolium spineless</Emphasis> ortholog specifies both larval and adult antennal identity

The morphology of insect antennae varies widely among species, but our understanding of antennal development comes almost solely from studies of one species—the fruit fly, Drosophila melanogaster. Moreover, this knowledge applies mostly to adult structures, since Drosophila lacks external larval appendages. In contrast to Drosophila, the red flour beetle, Tribolium castaneum, has both larval and adult antennae, which are very different from one another in morphology. Thus, Tribolium provides an ideal system to compare modes of antennal development both within and between species. Here, we report that the Tribolium ortholog of spineless (Tc-ss) is required in both the larval and adult antennae. Knockdown of Tc-ss by RNAi during either larval or imaginal development causes transformation of the distal portion of the antennae to legs. Thus, the function of ss is conserved between Drosophila and Tribolium with respect to adult antennal specification and also between Tribolium larval and adult antennal development. The similarity of the Tc-ss RNAi phenotype to that of a classically described Tribolium mutation, antennapedia (ap) (of no relationship to the Drosophila Hox gene of the same name), led us to characterize the original ap mutation and two newly identified ap alleles. Our mapping and phenotypic data suggest that Tc-ss is the best candidate for the ap locus. These results represent a first step in characterizing larval and adult antennal patterning in Tribolium, which should provide important insights into the evolution of insect antennal development.     

Refinement of a cell line based artificial diet for rearing the parasitoid wasp, Trichogramma pretiosum

An artificial diet incorporating insect cells originally developed for Trichogramma australicum Girault (Hymenoptera: Trichogrammatidae) was successfully used to rear Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae). To refine the diet, individual components were removed. Chicken egg yolk and the insect cells were identified as the most important components for T. pretiosum development. Their removal resulted in few pupae and no adults. Removal of Grace’s insect medium, a common component of artificial diets, was found to markedly improve the development of T. pretiosum, producing 60% larva to pupa transition and 19% pupa to adult transition. There was no significant difference in T. pretiosum development on diets in which milk powder, malt powder or infant formula were interchanged, despite differences in nutrient composition. The use of yeast extract resulted in significantly higher survival to the adult stage when compared with yeast hydrolysate enzymatic and a combination of yeast extract and yeast hydrolysate enzymatic. Comparison of four antimicrobial agents showed the antibacterial agent Gentamycin and the antifungal agent Nystatin had the least detrimental effect on T. pretiosum development. The use of insect cell line diets has the potential to simplify artificial diet production and significantly reduce T. pretiosum production costs in Australia compared to diets using insect hemolymph or the use of natural or factitious hosts.     

Pollen as an alternative food for Harmonia axyridis

The current study examines the potential of the multicoloured Asian lady beetle Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) to use pollen as a food to sustain development and reproduction in the absence of insect prey. Three populations of H. axyridis were used in this study: a long-term laboratory population (since 1998) and a melanic and non-melanic population originating from field collected individuals in Belgium. The insects were allowed to develop and reproduce on frozen eggs of Ephestia kuehniella Zeller (Lepidoptera: Phycitidae), frozen moist bee pollen or an even mixture of the two. Females of the field population offered the mixed diet initiated oviposition sooner than those fed only E. kuehniella eggs, but other developmental and reproductive traits were similar on these diets. A diet of pollen alone allowed 35–48% of the larvae of the field population of H. axyridis to successfully reach adulthood. However, developmental time for these individuals was prolonged by 31–49% and adult body weight was reduced by 37–68%, compared to individuals offered the diets containing E. kuehniella eggs. When fed exclusively on pollen in their larval and adult life, about 40% of the adult females of either field population were able to produce a small number of viable eggs. The laboratory and field strains differed in their response to diet for a number of developmental and reproductive traits. The exploitation of pollen and other plant foods at times when insect prey is scarce, may offer a further competitive advantage to the non-indigenous coccinellid H. axyridis over native European predatory lady beetles that share the same niche and are less capable of using pollen as an alternative food.     

Diversification and Independent Evolution of Troponin C Genes in Insects

Troponin C (TpnC), the calcium-binding subunit of the troponin regulatory complex in the muscle thin filament, is encoded by multiple genes in insects. To understand how TpnC genes have evolved, we characterized the gene number and structure in a number of insect species. The TpnC gene complement is five genes in Drosophilidae as previously reported for D. melanogaster. Gene structures are almost identical in D. pseudoobscura, D. suboboscura, and D. virilis. Developmental patterns of expression are also conserved in Drosophila subobscura and D. virilis. Similar, but not completely equivalent, TpnC gene repertoires have been identified in the Anopheles gambiae and Apis mellifera genomes. Insect TpnC sequences can be divided into three groups, allowing a systematic classification of newly identified genes. The pattern of expression of the Apis mellifera genes essentially agrees with the pattern in Drosophilidae, providing further functional support to the classification. A model for the evolution of the TpnC genes is proposed including the most likely pathway of insect TpnC diversification. Our results suggest that the rapid increase in number and sequence specialization of the adult Type III isoforms can be correlated with the evolution of the holometabolous mode of development and the acquisition of asynchronous indirect flight muscle function in insects. This evolutionarily specialization has probably been achieved independently in different insect orders.Reviewing Editor: Dr. Rüdiger Cerff     

Adult emergence phenology in checkerspot butterflies: the effects of macroclimate,topoclimate, and population history

The prediction of adult emergence times in insect populations can be greatly complicated by microclimatic gradients, especially in circumstances where distributions of juveniles along those gradients vary from year to year. To investigate adult emergence patterns in topographically heterogeneous habitats, we built a model of postdiapause development of the Bay checkerspot butterfly, Euphydryas editha bayensis. The model uses slope-specific insolation as the rate-controlling variable, and accounts for both solar exposure of the habitat and cloud cover. Instar-specific larval mass gains per unit of insolation were determined from mark-recapture experiments. A small correction for daily low temperatures was used to calibrate the model to five years of field data on larval mass. The model predicted mean mass of 90% of larval samples within 4 clear days over a 70–120 day growing season. The magnitude of spatial variation in emergence times across habitat slopes is greater than annual variation in emergence times due to yearly weather conditions. Historical variation (yearly shifts in larval distributions across slopes) is an important determinant of mean population emergence dates. All of these factors need to be considered in understanding adult emergence phenology in this butterfly and in other insects inhabiting heterogeneous thermal environments. Such an understanding can be useful in managing insect populations for both pest control and conservation.     

基于高通量测序的不同虫态洋虫内共生微生物群落分析

【目的】为分析不同虫态下洋虫内共生微生物菌群组成情况,以成虫和幼虫两种虫态为研究对象。【方法】通过对洋虫内共生微生物提取及高通量测序分析,获得不同样品中微生物组成结构及变化情况。【结果】不同虫态下,随着生长发育的进行,洋虫体内细菌在丰度和多样性两个方面都有很大变化,成虫中的菌群数量相对较少,多样性较幼虫也明显降低。在几种特定微生物组成上不同虫态也存在着较大的差异,成虫中,漫游球菌属和乳酸菌菌属为优势菌属;幼虫体内乳酸菌菌属为优势菌属。真菌变化不明显,孢囊线黑粉酵母菌属为其优势菌属。【结论】研究结果将为后继洋虫生物资源的研究提供相关信息,为洋虫内共生微生物资源开发与利用提供理论依据。     

Laboratory and Field Observations of the Behavior of <Emphasis Type="Italic">Eustenopus villosus</Emphasis> while Feeding and Ovipositing on Yellow Starthistle

The feeding and oviposition behavior of postdiapausal Eustenopus villosus (Boheman) on young and late stage buds, respectively of yellow starthistle, Centaurea solstitialis L., was documented in the laboratory and field. Postdiapausal adult feeding on young buds took over an hour to complete in most cases and was conducted by both sexes. Feeding bouts generally occurred in the sequence of explore, feeding, and budwalk. Oviposition included a feeding phase to prepare an oviposition cavity within the bud; thus, oviposition bouts included some of the same behavioral elements as postdiapausal feeding. The standard sequence of behavioral elements involved with oviposition included exploring, feeding, turning, ovipositing, and budwalking. The feeding element during the oviposition bout often lasted 2 h and was similar in the field and in the lab. Postdiapausal adult feeding on young capitula and stems, and larval feeding on developing ovaries and achenes, makes this weevil especially destructive on a per insect basis.     

Founding Swarms in a Tropical Social Wasp: Adult Mortality, Emigration Distance, and Swarm Size

When colonies of swarm-founding wasps lose their nests to predation or accident, the entire adult population escapes, emigrates as an absconding swarm, and renests elsewhere. Such an event causes a reduction in the adult population due to losses during the emigration itself and to adult attrition without replacement during the subsequent preemergence growth period in the new nest. We addressed the first of these sources of mortality for 27 absconding swarms of Polybia occidentalis in Costa Rica. Adult mortality over the day that included swarm emigration averaged 0.044 ± 0.039 (SD) of the original population and was a weak positive function of distance moved, but not of swarm size. A larger data set showed that emigration distance increased with swarm size. This is the first study to measure mortality rates during emigration in a swarm-founding social insect.     

Defects in the adult abdominal integument ofDrosophila caused by mutations intorpedo,a DER homolog

TheDrosophila homolog of the vertebrate EGF receptor (DER) gene is encoded by thetorpedo (top) locus. We examined the role oftop in the development and differentiation of the integument of the adult abdomen ofDrosophila, by analysing these processes in transheterozygotes of twotop alleles. The mutation, when compared to the wild type, affected mitosis, spreading and differentiation of adult epidermal cells derived from the various histoblast and spiracular nests. Our observations indicate that the need for wild-typetop gene product becomes critical after pupation, and the requirement continues throughout the rest of adult development for the normal morphogenesis of the abdominal integument and spiracles.We dedicate this paper to the memory of the doyen of insect physiology, Sir Vincent Briar Wigglesworth, for his avalanche of seminal studies that showed the value of insects to solve key biological problems.     

Infanticide Avoidance by the Granary Weevil, <Emphasis Type="Italic">Sitophilus granarius</Emphasis> (L.) (Coleoptera: Curculionidae): The Role of Harbourage Markers,Oviposition Markers,and Egg-Plugs

In dual choice experiments, adult female granary weevils, Sitophilus granarius L. (Coleoptera: Curculionidae), demonstrated no feeding preference for wheat that had been previously exposed to male and female conspecifics but avoided feeding on grain parasitized with related or unrelated conspecific eggs. Feeding avoidance was lost if egg-parasitized grains possessed an additional unsealed oviposition cavity. Females also preferred to consume artificially damaged grains over undamaged grains. These results suggest that a harbourage-derived feeding deterrent does not exist but an oviposition-derived feeding deterrent does, and that this deterrent protects S. granarius conspecifics from infanticide regardless of their relationship to the adult insect. Egg-plugs may also serve to reduce infanticide by preventing the release of phagostimulatory compounds from oviposition-damaged wheat.     

Growth and development of a generalist insect herbivore, Operophtera brumata, on original and alternative host plants

A generalist feeding strategy is common among eruptive insect herbivores but the ultimate reasons for a generalist strategy are not clear. Although generalist insect herbivores are able to complete their life cycle on several species of host plants, there is wide variation in the performance of individuals grown on different hosts. We examined whether different populations of Operophtera brumata are adapted to use the host species which is locally most abundant, and how the host plant affects growth and development of the insect. We reared two allopatric populations (eastern Finland, Prunus padus; south-west Finland, Quercus robur) on four species of host plants (Pr. padus, Populus tremula, Q. robur, Salix phylicifolia) from neonate larvae to the adult stage and measured the growth and development of individuals and the timing of adult hatching. The performance of both populations was best on Pr. padus, and the south-western population, originally on Q. robur, was well adapted to this host. The host affected the growth of females more than that of males. The host plant had an unexpected effect on hatching times of the adults. Individuals grown on the original host hatched in normal synchrony, i.e. males 6–7 days before females; but on alternative hosts this synchrony was disturbed. As is common in eruptive, capital-breeding generalist moths where female fecundity is linked to weight, host quality is critical for the flightless females of O. brumata. We suggest that in a heterogeneous environment the disturbing effect of alternative host plants on adult emergence may decrease the population density and growth rate compared to the potential maximum in a homogeneous environment. Received: 8 July 1999 / Accepted: 29 October 1999     

Volatiles that encode host-plant quality in the grapevine moth

Plant volatiles are signals used by herbivorous insects to locate host plants and select oviposition sites. Whether such volatiles are used as indicators of plant quality by adult insects in search of host plants has been rarely tested. We tested whether volatiles indicate plant quality by studying the oviposition of the grapevine moth Lobesia botrana on the grapevine plant Vitis vinifera. Host plants were infected with a variety of microorganisms, and larval fitness was correlated to the infected state of the substrate. Our results show an oviposition preference for volatiles that is significantly correlated with the fitness of the substrate. The chemical profiles of the bouquets from each V. vinifera–microorganism system are clearly differentiated in a PCA analysis. Both the volatile signal and the quality of the plant as larval food were affected by the introduction of microorganisms. Our study represents a broad approach to the study of plant–insect interactions by considering not only the direct effect of the plant but also the effect of plant–microorganism interactions on insect population dynamics.     

Identification of the Drosophila and Tribolium receptors for the recently discovered insect RYamide neuropeptides

One year ago, we discovered a new family of insect RYamide neuropeptides, which has the C-terminal consensus sequence FFXXXRYamide, and which is widely occurring in most insects, including the fruitfly Drosophila melanogaster and the red flour beetle Tribolium castaneum (F. Hauser et al., J. Proteome Res. 9 (2010) 5296–5310). Here, we identify a Drosophila G-protein-coupled receptor (GPCR) coded for by gene CG5811 and its Tribolium GPCR ortholog as insect RYamide receptors. The Drosophila RYamide receptor is equally well activated (EC₅₀, 1 × 10⁻⁹ M) by the two Drosophila RYamide neuropeptides: RYamide-1 (PVFFVASRYamide) and RYamide-2 (NEHFFLGSRYamide), both contained in a preprohormone coded for by gene CG40733. The Tribolium receptor shows a somewhat higher affinity to Tribolium RYamide-2 (ADAFFLGPRYamide; EC₅₀, 5 × 10⁻⁹ M) than to Tribolium RYamide-1 (VQNLATFKTMMRYamide; EC₅₀, 7 × 10⁻⁸ M), which might be due to the fact that the last peptide does not completely follow the RYamide consensus sequence rule. There are other neuropeptides in insects that have similar C-terminal sequences (RWamide or RFamide), such as the FMRFamides, sulfakinins, myosuppressins, neuropeptides F, and the various short neuropeptides F. Amazingly, these neuropeptides show no cross-reactivity to the Tribolium RYamide receptor, while the Drosophila RYamide receptor is only very slightly activated by high concentrations (>10⁻⁶ M) of neuropeptide F and short neuropeptide F-1, showing that the two RYamide receptors are quite specific for activation by insect RYamides, and that the sequence FFXXXRYamide is needed for effective insect RYamide receptor activation. Phylogenetic tree analyses and other amino acid sequence comparisons show that the insect RYamide receptors are not closely related to any other known insect or invertebrate/vertebrate receptors, including mammalian neuropeptide Y and insect neuropeptide F and short neuropeptide F receptors. Gene expression data published in Flybase (www.flybase.org) show that the Drosophila CG5811 gene is significantly expressed in the hindgut of adult flies, suggesting a role of insect RYamides in digestion or water reabsorption.     

A laboratory technique for examining the flight activity of insects under controlled environment conditions

A technique was developed for studying the flight activity of the, black fly,Simulium arcticum, under controlled environment conditions. Wind speed, light, temperature and humidity could be controlled and monitored in the flight chambers. Accurate measurement and recording of individual insect activity were achieved with a high-sensitivity video recording and monitoring system. The controlled-environment monitoring system is adaptable for investigations of the environmental behaviour and physiology of various insect species.     

Comparative Development and Performance of Artificially Reared versus Host-RearedDiapetimorpha introita(Cresson) (Hymenoptera: Ichneumonidae) Wasps

Diapetimorpha introita(Cresson) (Hymenoptera: Ichneumonidae), a native ectoparasitoid ofSpodopteraspp. pupae, was reared in the laboratory on an artificial diet devoid of any insect host components. Diet-reared wasps demonstrated a propensity to search for and parasitize natural hosts in a field cage trial. Longevity of the diet-reared wasps was comparable with the longevity of wasps reared on host pupae. Survival rate ofD. introitawas 61.3% when reared on diet and 76.3% when reared on host pupae. Wasps reared on the artificial diet had longer developmental times, reduced fecundity, and reduced adult weights compared to wasps reared on host pupae. These studies suggest that future research efforts should focus on increasing fecundity and weight of diet-reared wasps and decreasing the mortality and developmental time of wasps reared on the artificial diet. The ability to rearD. introitaon an inexpensive, artificial diet significantly enhances the potential of mass rearing this parasitoid for inundative releases againstSpodopteraspp.     

Oviposition and feeding preferences of a flower-feeding weevil,Coelocephalapion aculeatum, in relation to conspecific damage to its host-plant

The oviposition and feeding preferences ofCoelocephalapion aculeatum Fall (Coleoptera: Apionidae), a host specific florivore ofMimosa pigra L. (Mimosaceae), were studied in relation to conspecific damage to its hostplant. Adults ofC. aculeatum cease ovipositing in inflorescences when the egg load reaches a number consistent with the larval carrying capacity of the inflorescence. The basis for this oviposition deterrence was examined by offering inflorescences damaged by adult feeding alone, larval feeding alone and a combination of adult feeding and oviposition. Adults preferred to oviposit on inflorescences which are not damaged by either adult feeding, larval feeding, or oviposition. No evidence for the existence of an oviposition deterring pheromone (ODP) was found. I suggest that the ability of a single host inflorescence to support the development of many larvae causes selection for the use of these oviposition deterring cues which can convey more quantitative information about the level of previous infestation than can ODPs. Adults fed a similar amount on damaged compared to undamaged inflorescences. These results assisted in the design of host range testing trials and allows predictions to be made about the effectiveness of this insect as a biological control agent.     

Activity of natural toxins against the silverleaf whitefly, Bemisia argentifolii, using a novel feeding bioassay system

An assay system was developed for the adult silverleaf whitefly, Bemisia argentifolii Bellows & Perring (Homoptera: Aleyrodidae). This practical device was constructed from standard disposable laboratory materials. Whiteflies were harvested directly from the leaf and into a collection vial by vacuum aspiration, minimizing physical damage to the insect. Insects were fed through a cellulose mixed-ester membrane on a diet of 20–27% sucrose alone or sucrose in an extract of zucchini (Curcurbita moschata Duchense). Mortality and honeydew production were scored. At 22–25°C and 50–55% relative humidity, control mortality generally remained at or below 15% during a 48 h assay period. The bioassay system was first tested using the insecticide, Imidacloprid, then used to screen a number of natural products with potential insecticidal activity against the whitefly. Destruxins extracted from the entomopathogenic fungus, Metarhizium anisopliae, and the natural insecticide/nematicide, Ivermectin, as well as bee venom and two of its components, melittin and phospholipase A₂, were found to be toxic to B. argentifolii. Five lectins, Bacillus thuringiensis toxins, gossypol, an extract of Paeciliomyces fumosoroseus, wasp and scorpion venom, and a trypsin inhibitor were not found to be insecticidal to adult B. argentifolii.     

Characterization of the pleiotropic phenotype of an ompR strain of Xenorhabdus nematophila

Xenorhabdus nematophila is an insect pathogen that forms a symbiotic association with the nematode, Steinernema carpocapsae. Xenorhabdus is carried into the insect host by the nematode, is released into the hemolymph and participates in killing the insect. The bacteria grow to high concentrations supporting the development of the nematode in the hemolymph. OmpR is a global regulatory protein involved in the regulation of porin genes, motility, acid tolerance and virulence in several enteric bacteria. To study the role of ompR in the lifecyle of Xenorhabdus, an ompR -minus strain was constructed. The ompR strain produced markedly reduced levels of the porin protein, OpnP and was both hypermotile and exhibited a hyperhemolysis phenotype. Inactivation of flhDC, the master regulator for flagella synthesis, eliminated hemolysin production in the ompR strain, suggesting that ompR regulates hemolysin production via flhDC. The ompR mutant strain was virulent towards insect hosts. However, when nematodes were grown on a mixture of the wild-type and the ompR strain, only the wild-type strain was recovered indicating that ompR is required for competitive symbiotic interaction with the nematode. The role of ompR in the symbiosis between the bacterium and the nematode is under investigation. This revised version was published online in August 2006 with corrections to the Cover Date.     

Cloning and characterization of an insecticidal crystal protein gene from Bacillus thuringiensis subspecies kenyae

A sporulating culture ofBacillus thuringiensis subsp.kenyae strain HD549 is toxic to larvae of lepidopteran insect species such asSpodoptera litura, Helicoverpa armigera andPhthorimaea operculella, and a dipteran insect,Culex fatigans. A 1.9-kb DNA fragment, PCR-amplified from HD549 using cryII-gene-specific primers, was cloned and expressed inE. coli. The recombinant protein produced 92% mortality in first-instar larvae ofSpodoptera litura and 86% inhibition of adult emergence inPhthorimaea operculella, but showed very low toxicity againstHelicoverpa armigera, and lower mortality against third-instar larvae of dipteran insectsCulex fatigans, Anopheles stephensi andAedes aegypti. The sequence of the cloned crystal protein gene showed almost complete homology with a mosquitocidal toxin gene fromBacillus thuringiensis var.kurstaki, with only five mutations scattered in different regions. Amino acid alignment with different insecticidal crystal proteins using the MUTALIN program suggested presence of the conserved block 3 region in the sequence of this protein. A mutation in codon 409 of this gene that changes a highly conserved phenylalanine residue to serine lies in this block.