bluuebunny/crossref_metadata_2025 huggingface dataset:
Reidentification of the female sex pheromone of the Indian meal moth, Plodia interpunctella: evidence for a four‐component pheromone blend
Authors: Zhu Junwei , Ryne Camilla , Unelius C. Rikard , Valeur Peter G. , Löfstedt Christer
Published: October 2003

Pheromone gland extracts from calling female Plodia interpunctella contained at least seven compounds that consistently elicited electroantennographic responses from male antennae upon gas chromatographic analysis. Three of these compounds were found to be the previously identified gland constituents, i.e., (Z,E)‐9,12‐tetradecadienyl acetate (Z9,E12‐14:OAc), (Z,E)‐9,12‐tetradecadienal (Z9,E12‐14:Ald) and (Z,E)‐9,12‐tetradecadienol (Z9,E12‐14:OH). A fourth EAD‐active compound was identified as (Z)‐9‐tetradecenyl acetate (Z9‐14:OAc). The homologue (Z)‐11‐hexadecenyl acetate (Z11‐16:OAc) was also identified in the extracts, but showed no EAD activity. The identity of all five compounds was confirmed by comparison of GC retention times and mass spectra with those of synthetic standards. In flight tunnel tests there were no significant differences in response of male P. interpunctella to the bait containing all four EAD‐active compounds and the responses to female gland extacts. A behavioural assay of different two‐compound blends in the flight tunnel showed that only addition of the corresponding aldehyde to the major pheromone component Z9,E12‐14:OAc raised the male response. A subtractive assay, however, revealed that the exclusion of any of the compounds from the complete four‐compound blend reduced its activity significantly. We thus conclude that the female‐produced sex pheromone of P. interpunctella consists of at least four components, i.e., Z9,E12‐14:OAc, Z9,E12‐14:Ald, Z9,E12‐14:OH and Z9‐14:OAc.

In a field trapping test performed in a storage facility, the four‐component blend attracted significantly more males of P. interpunctella than traps baited with Z9,E12‐14:OAc alone. In contrast, the highest number of Ephestia kuehniella males was found in the traps baited with this major component, suggesting that the secondary pheromone components contribute to the species specificity of the blend.
Comparison of Diuraphis noxia resistance in wheat isolines and plant introduction lines
Authors: Budak Sibel , Quisenberry S.S. , Ni X.
Published: October 2003

The Russian wheat aphid, Diuraphis noxia (Mordvilko), is one of the most important aphid pests of wheat, Triticum aestivum L., worldwide. Among the various pest management options, plant resistance is an economical management tactic to control D. noxia in cereal crops such as wheat. Researchers have identified D. noxia resistant germplasm and it has been incorporated into wheat. This study compared D. noxia resistance between the ’Betta‘ wheat isolines Betta‐Dn1, Betta‐Dn2, and Betta‐Dn5 and their corresponding donor gene plant introduction (PI) lines PI 137739 (Dn1), PI 262660 (Dn2), and PI 294994 (Dn5). Although the Betta isolines and PI lines showed D. noxia resistance when compared with Betta wheat, the degree of resistance in the isolines to D. noxia was different from their corresponding PI donors. Aphid number, aphid fecundity, and biomass per aphid were not different between Betta‐Dn1 and PI 137739 or Betta‐Dn2 and PI 262660; however, the same parameters were significantly lower on PI 294994 compared with Betta‐Dn5. This indicated that aphid resistance in PI 137739 and PI 262660 was probably governed by a single dominant gene, while the resistance in PI 294994 was controlled by more than one gene. Additionally, plant biomass reduction was aphid density dependent, which suggested that use of appropriate aphid infestation level is important when using plant biomass reduction as an indicator of resistance. Plant resistance categorization showed that there was no detectable difference in antixenosis among the seven lines evaluated. However, the higher aphid fecundity observed on PI 262660 compared with PI 137739 and PI 294994, in addition to no significant differences among the three PIs in plant biomass reduction, suggested PI 262660 was a tolerant line, while PI 137739 and PI 294994 were antibiotic lines. Plant tolerance could not be elucidated among the three Betta isolines using aphid fecundity and plant biomass reduction as indicators.
Host influences on sex ratio, longevity, and egg load of two Metaphycus species parasitic on soft scales: implications for insectary rearing
Authors: Bernal Julio S. , Luck Robert F. , Morse Joseph G.
Published: October 2003

Metaphycus flavus (Howard) and M. stanleyi Compere (Hymenoptera: Encyrtidae) are currently being screened for use as augmentative biological control agents of citrus‐infesting soft scales (Homoptera: Coccidae). Two factors were investigated, host quality‐dependent sex allocation and local mate competition, which likely influence these parasitoid's sex allocation strategies and are therefore of interest for their mass‐rearing. The results of these studies suggested that, under the mass‐rearing protocol that is envisioned for these parasitoids, offspring sex ratios in both M. flavus and M. stanleyi are dominated by host quality (= size) influences, but not by interactions with other females. These results indicated that host size strongly influences offspring sex ratios and brood sizes; larger hosts led to more female offspring and larger broods. In contrast, increasing the number of parental females did not lead to fewer female offspring as expected under local mate competition. Additionally, within‐brood sex ratios did not vary with brood size; this result is inconsistent with expected sex ratios due to local mate competition. Other results also indicated that host quality was a dominant influence on M. flavus‘ and M. stanleyi's sex ratios. Larger hosts led to a larger size in the emerging wasps, and larger wasps had greater egg loads and lived longer than smaller wasps. However, wasp longevity, and the influence of wasp size on longevity were mediated by a wasp's diet. Metaphycus flavus females lived the longest when they had access to hosts, honey, and water, followed by honey and water, and shortest when they had access to water alone; M. stanleyi females lived longest with honey and water, followed by hosts, honey, and water, and shortest with water alone. Greater wasp size led to greater longevity in females only when they had access to food (honey, or hosts and honey). Finally, other results suggested that both M. flavus and M. stanleyi are facultatively gregarious. Wasp size did not decrease with brood size as expected under superparasitism. Overall, the results of these studies suggested that holding newly emerged females of both M. flavus and M. stanleyi for several days in the presence of an appropriate food source before field release could enhance a female's performance as an augmentative biological control agent. It increases their initial life expectancy following release, and maximizes the females‘ egg load (both Metaphycus species) and resources for replacing oviposited eggs (M. flavus only).
Molecular markers to differentiate two morphologically‐close species of the genus Sitobion
Authors: Figueroa Christian C. , Simon Jean‐Christophe , Le Gallic Jean‐Francois , Niemeyer Hermann M.
Published: October 2003

A set of molecular markers to differentiate the aphid (Hemiptera: Aphidoidea) species Sitobion avenae (Fabricius) from Sitobion fragariae (Walker), is presented. These markers correspond to (1) a region of the mitochondrial DNA, (2) five species‐specific RAPD banding patterns and (3) four microsatellite loci. Each of the markers was able to clearly distinguish between the species. The utility of each molecular marker is discussed. Mitochondrial DNA is best applicable to species determination and relative abundance, RAPDs to the evaluation of genetic diversity, and microsatellites to the assessment of the population genetic structure; the combined use of mtDNA with the other techniques can be of importance when the presence of hybrids is suspected, and RAPDs with microsatellites are best used together in population genetics and host preference studies.
Predatory behavior of Delphastus pusillus in relation to the phenotypic plasticity of Bemisia tabaci nymphs
Authors: Guershon Moshe , Gerling Dan
Published: October 2003

Phenotypic plasticity in Bemisia tabaci is expressed, among others, through the degree of nymphal setosity. We tested the hypothesis that the setose phenotype of nymphs can act as a defense mechanism against the predatory coccinellid Delphastus pusillus. Since it has been shown that the relative number of each phenotype is directly correlated with the tomentosity level of the host leaf, our study included characterization of D. pusillus predatory activity when exposed to the different nymphs upon two different leaf types: glabrous and tomentose. Leaf trichomes were found responsible for differences in durations of observed events, their frequency and transitions between events, leading to a break in the predatory sequence regularly found on glabrous leaves. However, despite this break, observational data and functional response tests showed no differences in prey consumption when the predator was exposed to each prey type separately. This is explained by a particular foraging behavior displayed by D. pusillus on tomentose leaves that included walking upon leaf trichomes while performing a vertical introduction of the head between the trichomes, thus reaching the leaf surface. Differences in handling times between the nymph phenotypes were recorded during direct observations of patch time allocation, but these did not result in significant differences in the number of prey eaten. Moreover, our estimates of handling time, calculated with a type II functional response equation, also failed to show these differences. However, foraging predators were more prone to discover smooth nymphs than setose nymphs when the former were offered on tomentose leaves. The significance of these findings in the context of predator‐prey‐plant interactions is discussed.
The toxicity of Jack bean (Canavalia ensiformis) cotyledon and seed coat proteins to the cowpea weevil (Callosobruchus maculatus)
Authors: Oliveira Antônia Elenir A. , Sales Maurício P. , Machado Olga Lima T. , Fernandes Kátia Valevski S. , Xavier‐Filho José
Published: October 2003

The seeds of the Jack bean, Canavalia ensiformis (L) DC are known to contain several toxic substances that prevent their utilisation as food for humans and animals. The lectin concanavalin A and the enzyme urease are the best known of these proteins. We have found that many proteins present in the seeds of the Jack bean, like trypsin inhibitors and canatoxin, are detrimental to the development of the bruchid insect Callosobruchus maculatus (F) (Coleoptera: Bruchidae). Among these proteins, canavalin (vicilin, 7S globulin) was found to be expressed in the seed coat. We suggest that seed coat canavalin, in addition to other detrimental proteins expressed in this tissue, may have been of importance in the evolutionary discrimination of the seeds of this legume by non‐pest bruchids.
The biology and phenology of the citrus whitefly, Dialeurodes citri, on citrus in the Coastal Plain of Israel
Authors: Argov Yael , Rössler Yoram , Voet Hillary , Rosen David
Published: October 2003

The citrus whitefly, Dialeurodes citri (Ashmead) (Homoptera: Aleyrodidae) (CWF), is a polyphagous citrus pest, originating in S. E. Asia, which was first discovered in the Western Galilee region of Israel in 1975. The larval instars of CWF secrete honeydew, and the sooty mould fungus, which develops on the honeydew, causes damage to the tree and its fruit. In observations made in Israel between 1987 and 1991 CWF usually completed three generations per year, although a small proportion of the population had two or four generations. From October to April a combination of shortened photoperiod and reduced temperature arrest the development of CWF in the fourth larval instar. The average length of the life cycle from egg to adult emergence was 65 days in the first generation (April–June), 52 days in the second generation (July–August) and 8 months in the third generation (September–April). Under laboratory conditions of L16: D8 and 25 °C, the mean developmental time was 54 days, and the duration of the egg, first larval instar, second larval instar, third larval instar, fourth larval instar and putative pupa (red eyes) were 12.1, 6.5, 5.5, 7.6, 18, and 4.7 days, respectively. Adults prefer to lay their eggs on young, fully developed citrus leaves, but also oviposit on older leaves. The inner region and shaded sides of the tree are preferred for oviposition.
Jasmonic acid induces the production of gerbera volatiles that attract the biological control agent Phytoseiulus persimilis
Authors: Gols R. , Posthumus M.A. , Dicke M.
Published: October 2003

Jasmonic acid (JA) is a plant hormone that is involved in the induction of plant defence in response to herbivore attack. We studied the effect of exposure of gerbera leaves to JA on indirect plant defence, i.e. attraction of natural enemies of herbivores. Treatment of gerbera leaves with JA or feeding damage by the herbivorous spider mite Tetranychus urticae, both induced the production of a complex odour blend that attracts the predatory mite Phytoseiulus persimilis. This phytoseiid predator is a very effective biological control agent of the spider mite T. urticae. Comparison of headspace composition of gerbera leaves exposed to either JA or T. urticae revealed a large degree of resemblance, but some quantitative and qualitative differences were recorded. The major chemical group in both treatments is formed by the terpenoids which quantitatively comprised up to 80% of the total odour blend. These terpenoids included (E)‐4,8‐dimethyl‐1,3,7‐nonatriene, (E)‐β‐ocimene and linalool that are known to attract P. persimilis. Aldehydes, alcohols, esters and ketones, together with nitrogenous compounds formed the remaining constituents of the odour blend. The induction of predator attractants in plants by JA may be applied in biological control programs, which is discussed in this paper.
Differences in tomato spotted wilt virus vector competency between males and females of Frankliniella occidentalis
Authors: van de Wetering Fennet , van der Hoek Marieke , Goldbach Rob , Peters Dick
Published: October 2003

Possible differences in tomato spotted wilt virus (TSWV) transmission vector competency between Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) males and females were investigated. The males of the Dutch reference population NL3 transmitted TSWV at a notably higher rate (57%) than the females (32%). The viruliferous males also transmitted more frequently within the first six days after adult emergence than the females. For both sexes, the transmission efficiency dropped with age, simultaneously with the consumption rate. The higher vector efficiency for males appeared to be a general phenomenon as this feature was also found for thirteen other F. occidentalis populations, which originated from distinct geographic regions.
The influence of oviposition phenology on survival in host races of Eurosta solidaginis
Authors: Horner John D. , Craig Timothy P. , Itami Joanne K.
Published: October 2003

Phenological differences between host plants can contribute to allochronic isolation of host races of phytophagous insects. Host races of the gallmaking fly, Eurosta solidaginis, that live on different species of goldenrod (Solidago altissima and S. gigantea) exhibit different emergence phenologies. These differences could result from adaptation to corresponding phenological differences between the hosts in periods of optimal suitability for gall formation and survival to adulthood. In order to test this, some flies of each host race were allowed to emerge naturally while the emergence times of others were manipulated to correspond to the emergence and oviposition periods of the other host race. Percent gall formation and survival to adulthood were examined for three oviposition periods: the peak time of emergence and oviposition of the earlier‐emerging host race (that from S. gigantea), that of the later‐emerging host race (that from S. altissima), and a week after the peak emergence of the host race from S. altissima. Flies of both host races were allowed to ovipuncture plants of the appropriate species during each of these periods. Plant relative growth rates were measured during each of these periods. The experiment was repeated twice over a two‐year period. Relative growth rates of both host species were highest during the earliest oviposition period (the period during which the host race from S. gigantea normally emerges). Percent gall formation was significantly correlated with plant relative growth rate, but the coefficient of determination was low. In both years of the study, percent gall formation of both host races was highest during the earliest oviposition period (the period during which the host race from S. gigantea normally oviposits). Likewise, percent survival to adulthood in both host races was highest during the earliest oviposition period. There was no significant effect of oviposition period on the percent of larval death due to parasitism by Eurytoma gigantea or predation by Mordellistena unicolor. These results suggest that the host race from S. altissima does not emerge at the time that its host is optimally suited for gall formation or survival to adulthood. Therefore, differences in emergence phenologies do not appear to be due to corresponding phenological differences between the host species in suitability for gall formation or survival to adulthood.
Spring colonisation of orchards by Anthonomus pomorum from adjacent forest borders
Authors: Toepfer St. , Gu H. , Dorn S.
Published: October 2003

The early‐season dispersal of the overwintered apple blossom weevil, Anthonomus pomorum (L.) (Coleoptera: Curculionidae), is a crucial stage in the colonisation of dwarf apple orchards adjacent to forests. We have conducted release‐recapture studies with 1700 to 4000 marked weevils at two orchard sites in Switzerland over 2 years to characterise the spatial and temporal pattern of the dispersal process. The dispersal and colonisation of orchards in spring by overwintered weevils is dependent upon the prevailing temperature.

An orientated dispersal from the forest border to the centre of the orchard was observed consistently, irrespective of the angle of the apple tree rows with respect to the forest border or of climatic conditions. The average dispersal distance of the weevils was 19 m. Approximately one third of the weevil population remained on the first tree encountered, the remainder of the population moved over short distances mainly along the tree rows. This dispersal pattern led to a strong ’edge effect‘ with higher numbers of weevils occurring at the edges adjoining the forests as compared to the centre of orchards. The relevance of these findings to population dynamics and management of the pest is discussed.
Niche overlap and interspecific association between Chilo partellus and Chilo orichalcociliellus on the Kenya coast
Authors: Ofomata V.C. , Overholt W.A. , Van Huis A. , Egwuatu R.I. , Ngi‐Song A.J.
Published: October 2003

Chilo partellus (Swinhoe) and Chilo orichalcociliellus Strand (Lepidoptera: Crambidae) occur sympatrically on the Kenya coast and are injurious to maize and sorghum. Evidence over a period of 30 years indicates that the indigenous stem borer, C. orichalcociliellus, is being gradually displaced by the exotic stem borer, C. partellus. The two species have overlapping niches, but the specific mechanisms driving the displacement are unknown. The distribution and extent of niche overlap and interspecific association between C. partellus and C. orichalcociliellus were investigated in cultivated and wild host plants. No difference in the within‐plant distribution of the two borer species in maize and sorghum was found. A niche overlap of 83.7% between C. partellus and C. orichalcociliellus was found. A weak positive association was found between small‐, medium‐, and large‐sized larvae of C. partellus and C. orichalcociliellus. However, as larvae grew, the association decreased with no significant association at the pupal stage. No negative association was found between C. partellus and C. orichalcociliellus, suggesting that the two species do not avoid or directly harm each other. The partial displacement of C. orichalcociliellus may therefore, be attributed to intrinsically superior attributes of C. partellus that indirectly affect the survival of C. orichalcociliellus.
Effects of temperature and photoperiod on development and oviposition of the legume flower thrips, Megalurothrips sjostedti
Authors: Ekesi S. , Maniania N.K. , Onu I.
Published: October 2003

Megalurothrips sjostedti is an economic pest of cowpea in tropical Africa. There are no reports of the effect of temperature on the development of the pest and no diapause has been detected. The developmental rate and reproduction of M. sjostedti was studied under six constant temperatures (14, 17, 20, 23, 26 and 29 °C ) and a photoperiod of L12:D12 in the laboratory. Total developmental time ranged from 33.1 days at 14 °C to 19.2 days at 26 °C. At 29 °C, all larvae died during hatching. Egg, larval and pupal stages required 94.3, 97.1 and 105.3 deg‐days (DD) above a threshold of 8.2, 9.1 and 10.4 °C, respectively, to complete development. Total developmental cycle was completed at 163.9 DD above a threshold of 12.6 °C. Adult longevity was lowest (11.1 days) at 29 °C and highest (28.7 days) at 14 °C. At constant temperatures, the highest pre‐oviposition period was observed at 29 °C under a photoperiod of L16:D8. Egg production also ceased at this temperature/photoperiod combination. Total fecundity was highest at 26 °C under L10:D14. At cyclical temperatures, pre‐oviposition period was longest (12.4 days) at 20/29 °C under L16:D8. Total fecundity was highest (168.4 eggs) at 14/26 °C under L10:D14, and lowest (8.2 eggs) at 20/29 °C under L16:D8. The significance of these findings in the management of M. sjostedti is discussed.
The influence of floral character on the foraging behaviour of the hoverfly, Episyrphus balteatus
Authors: Sutherland Jamie P. , Sullivan Matthew S. , Poppy Guy M.
Published: October 2003

A bioassay to examine the foraging behaviour of the aphidophagous hoverfly, Episyrphus balteatus was used in which various stimuli purported to influence flower choice were tested using model flowers. In choice experiments, E. balteatus exhibited enhanced behavioural responses to the colour yellow, as previously seen in Eristalis by several workers. Previous suggestions that the generalist forager E. balteatus has no preference for colour are re‐examined in the light of this new evidence. The other advertisement cue tested, size, was also demonstrated to play an important role in determining foraging behaviour, with the smaller artificial flowers seemingly preferred. Of the rewards tested, E. balteatus showed preference for the greatest nectar concentrations, whilst increasing pollen did not affect behaviour. These bioassays provided an opportunity to isolate the individual components of decision‐making by E. balteatus during foraging. The separation of sexes and ages in these experiments permitted analysis of inter‐sexual and inter‐generation differences in behaviour, a factor apparently not investigated in previous work.
Effect of plant lectins on larval development of the legume pod borer, Maruca vitrata
Authors: Machuka J. , Van Damme E.J.M. , Peumans W.J. , Jackai L.E.N.
Published: October 2003

The legume pod‐borer Maruca vitrata (Fabricius), [Lepidoptera: Pyralidae] is a major constraint restricting increased cowpea production in tropical Africa and Asia. Since lectins are known to have insecticidal properties against several pests, a survey was undertaken to screen for the effects of 25 lectins from 15 plant families on the development of Maruca pod borer (MPB) larvae. The list included 8 galactose/N‐acetylgalactosamine‐, 7 mannose‐, 5 complex glycan‐, 2 sialic acid‐ and 3, N‐acetylglucosamine‐specific lectins. Feeding bioassays using artificial diet were carried out at 2% (w/w) topical levels. Although a total of 16 lectins had detrimental effects pertaining either to larval survival, weight, feeding inhibition, pupation, adult emergence and/or fecundity, only the Listera ovata agglutinin (LOA) (Orchidaceae) and Galanthus nivalis (Amaryllidaceae) agglutinin were effective against MPB larvae for all six parameters examined. Larval mortality and feeding inhibition caused by the most active lectin (LOA) was above 60%.
Dependence on host constituents controlling food acceptance by Manduca sexta larvae
Authors: del Campo C. Marta L. , Renwick J. Alan A.
Published: October 2003

The host range of Manduca sexta L. (Lepidoptera: Sphingidae) is restricted in nature to plants in the family Solanaceae. However, naive hatchling larvae often accept and continue their development on foliage from a wide spectrum of unrelated plants. In contrast, solanaceous‐experienced larvae refuse to feed on other plants. Experiments were designed to explore the role of constituents of various plants in this behavioral phenomenon. Fourth instar larvae reared on solanaceous hosts: tomato (Lycopersicon esculentum Mill.), potato (Solanum tuberosum L.), or tobacco (Nicotiana tabacum L.), and the leguminous non‐host cowpea (Vigna sinensis Savi), or on artificial diet based on wheat germ were tested for their acceptance or preference when offered a new diet in both choice and no‐choice situations. Under no‐choice conditions, acceptability of cowpea foliage was strongly affected by the larval dietary experience. Most larvae reared on solanaceous foliage did not feed, whereas those larvae reared on non‐solanaceous food readily accepted cowpea. Moreover, solanaceous foliage, leaf discs and extracts were readily accepted by larvae regardless of their dietary experience. Larvae reared on any of the solanaceous plants strongly preferred cowpea discs that were treated with solanaceous extract, while larvae reared on non‐solanaceous diets did not discriminate between treated and control discs. Assays of cowpea extracts as well as acceptance of cowpea discs treated with solanaceous extract indicated a lack of detectable deterrent in cowpea. Our results suggest that the mechanism for induced host specificity in M. sexta larvae involves development of a dependence on solanaceous chemical constituents. We argue that this dependence on host plant chemistry has adaptive significance.
Effects of enhanced UV‐B radiation on a weedy forb (Plantago lanceolata) and its interactions with a generalist and specialist herbivore
Authors: McCloud Eric S. , Berenbaum May
Published: October 2003

Assessments of potential impacts of global climate change often focus exclusively on plants; however, as the base of most food webs, plants generally experience abiotic stresses concomitantly with biotic stresses. Longleaf plantain, Plantago lanceolata L., is a cosmopolitan temperate perennial weed that experiences a wide range of environmental conditions throughout its range. We examined the impacts of elevated levels of exposure to shortwave (UV‐B) radiation on this plant, on two herbivores associated with this plant, and on the plant‐herbivore interaction. Plantains were grown at 6 and 12 kJ m−2 d−1 BE300 UV‐B radiation and concentrations of iridoid glycosides (aucubin and catalpol), verbascosides, and nitrogen were measured. In terms of plant impacts, we found that iridoid glycoside concentrations were unchanged by elevated UV‐B radiation, whereas, in one experiment, the concentration of verbascosides in young leaves and levels of nitrogen in old leaves increased under elevated UV‐B radiation. Variation in plant chemistry due to leaf age and maternal family was greater than variation due to UV‐B exposure. When caterpillars were fed excised leaves from plants grown under elevated UV‐B, growth and survivorship of the specialist herbivore, Precis coenia Hbn. (Lepidoptera: Nymphalidae), were unaltered and growth of the generalist herbivore, Trichoplusia ni (Hbn.) (Lepidoptera: Noctuidae), was accelerated. When the caterpillars were reared on potted plants at high and low levels of UV‐B radiation, growth and survivorship of P. coenia were unchanged while growth of T. ni was significantly depressed by elevated UV‐B. Elevated UV‐B altered allocation patterns of above‐ground biomass in these plants; masses of crowns and reproductive tissue were reduced. UV‐B levels, however, did not affect distribution of damage to foliage inflicted by either species. In two additional experiments with artificial diet, designed to test the direct effect of UV‐B radiation on caterpillars, growth and survivorship of P. coenia were unaltered while survivorship of T. ni was significantly depressed when caterpillars were exposed to elevated UV‐B radiation. These studies collectively demonstrate that higher trophic level impacts of UV‐B‐induced changes in plants depend on the identity of the herbivore and its degree of adaptation not only to variation in hostplant quality but also variation in its light environment.
Wolbachia infection dynamics in experimental laboratory populations of Metaseiulus occidentalis
Authors: Johanowicz Denise L. , Hoy Marjorie A.
Published: October 2003

Wolbachia infection in arthropods may cause incompatibility between uninfected females and infected males, but infected females can reproduce with both infected and uninfected males, theoretically increasing the proportion of infected individuals in a polymorphic population. To determine whether the proportion of Wolbachia‐infected Metaseiulus occidentalis (Nesbitt) (Acari: Phytoseiidae) in a polymorphic population would increase over time, three populations were initiated with 10% infected and 90% cured eggs and monitored for 12 generations. Wolbachia infection did not spread rapidly through the populations. Imperfect transmission rates and fitness costs were detected that could prevent the rapid spread of this Wolbachia. Thus this Wolbachia may not be useful as a drive mechanism for inserting useful genes into field populations of M. occidentalis.
Colour variation and polyethism of the soldier caste in the termite Macrotermes bellicosus
Authors: Konate Souleymane , Leuthold Reinhard , Hari Markus , Veivers Pamela
Published: October 2003

Based on abdominal colour three categories of major soldiers were found in Macrotermes bellicosus (Smeathman) (Isoptera: Termitidae). The three main colour types, yellow, red and brown are due to the colour of the defence‐secretion stored in the labial gland's reservoirs. The order of these categories correlates with the uric acid titres of the whole individuals. It is concluded that colour could be used as a label for the relative age of a soldier. Age dependent polyethism was observed in soldiers: the individuals of the highest age class were the only ones leaving the nest to accompany the foraging workers, whereas all age categories were found inside the nest. After a significant loss of old individuals younger individuals show flexibility by replacing the missing outgoing nestmates. Caste regulation takes place by an increased rate of soldier development.
Metamorphosis‐associated proteolysis in Ceratitis capitata
Authors: Rabossi A. , Ación L. , Quesada‐Allué L.A.
Published: October 2003

The induction of several biochemical indicators of larval tissue histolysis in the Medfly, Ceratitis capitata (Diptera: Tephritidae) (Wiedemann) was studied. Using synchronized third instar larvae, we have determined the time of occurence of gut evacuation (12 h before puparium formation, bpf), disappearance of digestive enzymes (10 h bpf), and jumping from the food (8 h bpf). We can also correlate these events temporally with other early landmarks of metamorphosis.

The decrease in protein content between 0 hours and 144 hours after puparium formation (0–144 h apf) corresponds to a sharp increase of total acid proteolytic activity measured in vitro from 0 to 44 h apf. This activity appears to be lysosomal, judging by the activation of other lysosomal markers, such as acid phosphatase and β‐glycosidases. The maximum proteolytic activity occurs during the pre‐pupa to pupa transition, i.e. during morphogenesis from the cryptocephalic to the phanerocephalic pupa. The results of endopeptidase inhibitor assays indicate that in dipterans, members of the aspartic and cystein proteinase families are responsible for the degradation of larval tissues.
Factors influencing the distribution and feeding of the larvae of Chironomus riparius
Authors: Osborne S. , Hurrell S. , Simkiss K. , Leidi A.
Published: October 2003

Chironomids are the most widely distributed group of insect larvae in freshwater environments. They are frequently the dominant primary consumers and show competitive interactions due to their requirements for foraging space in suitable substrates. In order to investigate the factors involved in substrate selection a simple choice chamber has been constructed that enables larvae of Chironomus riparius Meigen (Diptera, Chironomidae) to select wells, in which they can establish tubes, according to a number of chemical and physical parameters. The statistical probabilities of them aggregating randomly in this way were calculated for a variety of occupancies. The larvae developed distinct patterns of non‐random aggregation in the wells. Subsequent experiments showed that the presence of food at sites of burrowing affected settling but physical irregularities were necessary in order to facilitate burrowing and establish random patterns. Once the animals had selected their habitat the rate of feeding on the sediment was relatively constant with a gut‐clearance time of about 12 h although starving the animals before or after feeding affected the rate of passage of sediment through the anterior of the gut.
Aufnahme von Wasserdampf aus ungesättigter Atmosphäre und ihre ökologische Bedeutung bei mesostigmaten Milben
Authors: Gaede K. , Knülle W.
Published: October 2003

Viele mesostigmate Milben mit unterschiedlicher Lebensweise und Habitatbeziehung absorbieren Wasserdampf aus ungesättigter Atmosphäre. Eingeschlossen sind hämatophage, räuberische, saprophage und polyphage Arten. Die niedrigste relative Feuchte, bei der Wasserdampfaufnahme möglich ist, reicht in Abhängigkeit von der Species von 76% bis 97% rel. Feuchte. Die Transpirationsraten der verschiedenen Arten unterscheiden sich um den Faktor 50. Durch Sorption und Transpiration folgt der Wassergehalt der Milben den Schwankungen der Umgebungsfeuchte ziemlich unvermittelt. Durch atmosphärische Wasserdampfaufnahme kompensieren die Milben Wasserverluste. Die kritische Gleichgewichtsluftfeuchte der Milben bezeichnet die relative Feuchte der umgebenden Luft bei der sich Sorption und Transpiration die Waage halten und bei der die Milben in der Lage sind, den Körperwassergehalt aufrecht zu erhalten. Die Versuche deuten auf einen oralen Sorptionsort hin. Sorption und Transpiration sind physiologische Parameter von ökologischer Bedeutung hinsichtlichWachstum von Populationen, Überleben und Habitatpräferenz. Eine Reihe von Arten sind als Parasiten und Agenzien der biologischen Schädlingsbekämpfung von grösserer wirtschaftlicher Bedeutung.
Behavioural induction in Drosophila: timing and specificity
Authors: Barron Andrew B. , Corbet Sarah A.
Published: October 2003

Experiments reported in this paper investigate the properties of a change in the responsiveness of adult Drosophila melanogaster induced by exposure to different rearing media. This effect has previously been described as habituation or associative learning. Exposure to food medium containing 0.08% menthol induced a positive response to menthol odour in a T‐maze olfactometer. A brief (one hour) exposure to mentholic food just before testing was sufficient to induce a change in responsiveness. The effect did not persist through periods of more than an hour of separation from mentholic medium.

Effects induced by exposure to a single compound were not specific to that compound alone. Menthol‐reared flies (MRFs) differed from plain reared flies (PRFs) in their responsiveness to the odours of benzaldehyde and ethyl acetate, as well as menthol, and exposure to ethyl acetate induced a change in response to menthol odour.

That there was an induced positive response to menthol in MRFs suggests that conventional habituation is insufficient to explain the induced change in responsiveness, but the generalised nature of this behavioural induction in MRFs is hard to explain in terms of associative learning. The mechanism underlying the induction remains elusive.
Glandular trichomes of Solanum berthaultii and its hybrids with potato deter oviposition and impair growth of potato tuber moth
Authors: Malakar Raksha , Tingey Ward M.
Published: October 2003

Glandular trichomes on foliage of the wild potato species, Solanum berthaultii Hawkes, deter oviposition by the potato tuber moth (PTM), Phthorimaea operculella Zeller and negatively affect other important performance parameters. Oviposition deterring factors are localized in the glandular trichomes of S. berthaultii. When mechanically transferred to foliage of a susceptible potato cultivar, trichome contents reduced egg laying by 97%. Removal of glandular trichomes from S. berthaultii foliage using a combination of chemical and mechanical procedures increased oviposition rates ca. 210‐fold. Removal of trichomes also led to increased mobility of larvae on the leaf surface, more leaf feeding, shorter larval development and larger pupae. The resistance conferred by glandular trichomes of S. berthaultii provides an important genetic trait potentially useful for management of PTM.
Statistical analysis of amounts and ratios in pheromone composition: a mixed model approach
Authors: Van Dongen Stefan
Published: October 2003

Analysis of variation in pheromone amounts and ratios between individuals is usually performed separately for amounts and ratios of the different components. Non‐parametric tests are regularly applied. This way of analysis is statistically correct, yet, limited for several reasons. The use of a parametric linear mixed model approach to analyze both amounts and ratios of different components at the same time is proposed. This method appears to be very flexible and may facilitate the analysis of pheromone data.
Laboratory and field experiments towards the development of an attract and kill strategy for the control of the codling moth, Cydia pomonella
Authors: Lösel Peter M. , Penners Gunter , Potting Roel P.J. , Ebbinghaus Dirk , Elbert Alfred , Scherkenbeck Jürgen
Published: October 2003

A viscous formulation based on castor oil containing the pyrethroid insecticide cyfluthrin and E8, E10‐dodecadienol, the main component of the codling moth sex pheromone, (Cydia pomonella L.: Tortricidae, Olethreutinae) was developed. The insecticidal performance of the formulation was evaluated in the laboratory using a tarsal‐contact bioassay. The pheromone dosage required to attract male moths to the formulation was determined in behavioural tests performed in a wind tunnel. The efficacy of formulations applied to seedlings of the host plant was further investigated in glasshouse experiments conducted with male moths in small wire‐gauze cages. The laboratory tests resulted in a formulation for preliminary field trials containing 4% cyfluthrin and 0.1% pheromone. During the 1995 growing season, experiments were conducted in apple orchards at three locations in Germany. The formulation was first applied to the bark of apple trees (Malus domestica) in mid May and then again in late July. A good level of control, comparable with a spray treatment using the insect growth regulator Alsystin was achieved. The potential of the attract and kill strategy, combining selective attraction of a pest species with the efficacy associated with a pyrethroid insecticide treatment, as a means of controlling the codling moth in commercial apple growing, is discussed.
Can chemical cues from blossom buds influence cultivar preference in the apple blossom weevil (Anthonomus pomorum)?
Authors: Kalinová Blanka , Stránský Karel , Harmatha Juraj , Čtvrtečka Richard , Žd'árek Jan
Published: October 2003

The post‐hibernating adults of the apple blossom weevil, Anthonomus pomorum (L.), show preferences for certain cultivars in mixed apple tree orchards. The degree of infestation of various cultivars was positively correlated with the density of flower buds at a comparable phenological stage, but the numbers of collected beetles were not linearly proportional to the bud density of different cultivars. Hence other possible factors, namely chemical ones, were investigated. Chromatographic analysis of apple tree bud emanations showed that volatiles from two different apple cultivars that show a different attractiveness to the beetles, differed in chemical composition. Several less volatile components of the bud emanation bouquet elicited antennographic responses in both male and female antennae. Four terpene hydrocarbons, namely 3‐carene, perillene, caryophyllene and (E,E)‐α‐farnesene, were identified among the components that produced distinct electrophysiological responses in the antennae. These findings support a hypothesis that the adult weevils use chemical cues for olfactory discrimination during host‐searching behaviour.
Host suitability of two biotypes of Bemisia tabaci on some common weeds
Authors: Muñiz M.
Published: October 2003

Significant differences in some reproductive parameters of the B and Q biotypes of Bemisia tabaci (Gennadius) with regard to four species of winter weeds were determined in a no‐choice assay. The highest fecundity (eggs) and fertility (pupae and adults) were obtained with Malva parviflora L. as host, followed by Capsella bursa‐pastoris L., Brassica kaber (DC) and Lactuca serriola L. The percentage of adult emergence (from egg to adult) was significantly higher (P < 0.001) with M. parviflora, C. bursa‐pastoris and B. kaber than with L. serriola. Except on L. serriola, the mean values of the reproductive parameters for the Q‐biotype were significantly (P < 0.05) greater than those for the B‐biotype. On the other hand, in choice experiments with summer weeds, both B‐ and Q‐biotypes preferred Datura stramonium L. and Solanum nigrum L. to Amaranthus retroflexus L., Chenopodium album L. and Echinochloa crus‐galli L. Significantly more males and females, and more pupae and empty pupal cases per plant were found on D. stramonium than on S. nigrum. Adult abundance on A. retroflexus, C. album and E. crus‐galli plants was very low. At a constant temperature of 26 ± 1 °C, the Q‐biotype developed significantly faster than the B‐biotype on S. nigrum and D. stramonium. Both biotypes required, for this development, significantly more days on D. stramonium than on S. nigrum. These results suggest that it is important to suppress the growth of M. parviflora, C. bursa‐pastoris, B. kaber, D. stramonium and S. nigrum in order to avoid the risk of further expansion of whitefly populations where these weeds and both B‐ an Q‐biotypes are present.
Biology and oviposition behavior of the phorid Apocephalus attophilus and the response of its host, the leaf‐cutting ant Atta laevigata
Authors: Erthal Milton , Tonhasca Athayde
Published: October 2003

Atta laevigata (Smith) (Hymenoptera: Formicidae) foragers collected in the field and parasitized by Apocephalus attophilus Borgmeier (Diptera: Phoridae) (1.2% of sampled ants) were larger and had lower survival rates than similar non‐parasitized foragers. Moreover, the size of parasitized ants was significantly correlated with the number of A. attophilus puparia and percentage of adult emergence. These results suggest that host size is important for the reproductive success of A. attophilus. Different from most ant‐parasitizing phorids, A. attophilus exhibits a pre‐oviposition behavior that involves walking towards the host and inspecting it, and this careful approach may be responsible for a relatively low percentage of parasitoid detection by A. laevigata. When an exotic resource (Acalypha sp. leaves) was placed on ants' foraging trails, more foragers were recruited, which resulted in the attraction of A. attophilus. The number and recruiting rates of small workers (minima) were significantly higher on leaves visited by A. attophilus, but larger foragers showed no response to phorids. These results demonstrated that minima react to the presence of A. attophilus and suggest a defensive role of these ants against phorid parasitism.
Integrating pesticide effects with inundative biological control: interpretation of pesticide toxicity curves for Anaphes iole in strawberries
Authors: Udayagiri Sujaya , Norton Andrew P. , Welter Stephen C.
Published: October 2003

We examined pesticide residue effects on the egg parasitoid Anaphes iole Girault (Hymenoptera: Mymaridae), an inundative biological control agent for Lygus hesperus Knight (Heteroptera: Miridae) in strawberries (Fragaria×ananassa Duchesne). Our objectives were to identify compatible pesticides, determine appropriate parasitoid release timings for minimizing harmful effects, and develop an approach for interpreting pesticide toxicity curves. Six insecticides, 2 acaricides and 6 fungicides were tested, and survivorship of adult A. iole exposed to foliar residues for 48 h, at 4–6 different times after pesticide application, was examined. A logistic function was developed for incorporating control mortality at each test date. Values for LT50 (Lethal Time for 50% mortality) and mortalities on day 1 (initial mortality) and day 13 (estimated maximum time parasitoid releases can be delayed under extreme summer conditions) were estimated. In the study, insecticide residues proved to be the most toxic, followed by those from acaricides while most fungicides were least toxic. Among insecticides, fenpropathrin, bifenthrin and carbaryl caused the greatest mortality (estimated mortality on day 13 > 75%). Residues of naled resulted in the least mortality (LT50LT50=3.2 days) followed by methomyl (LT50=8.3 days) and malathion (LT50=13.2 days). Estimated mortality = 12.3% on day 13 for the acaricide propargite and < 1% for abamectin. For the fungicides benomyl, captan, myclobutanil and thiram, estimated mortality on day 1 was < 1%, and for iprodione it was < 6%, indicating compatibility with A. iole releases. For sulfur, LT50=0, but the mortality decay curve was relatively flat (estimated mortality on day 13=13.6%). These results suggest possibilities for integrating A. iole releases with certain pesticide programs by appropriate timing of pesticide applications to minimize negative impacts.
Do Maculinea rebeli caterpillars provide vestigial mutualistic benefits to ants when living as social parasites inside Myrmica ant nests?
Authors: Wardlaw J.C. , Thomas J.A. , Elmes G.W.
Published: October 2003

Caterpillars of the lycaenid butterfly Maculinea rebeli Hirschke (Lepidoptera: Lycaenidae) live for 11–23 months as social parasites in Myrmica (Hymenoptera: Formicidae) red ant nests, a trait that is believed to have evolved from mutualistic myrmecophilous ancestry. Although Maculinea rebeli caterpillars harm Myrmica larvae, they simultaneously produce copious secretions which the adult worker ants imbibe, perhaps representing a vestige of the ancestral mutualism. We report the results of laboratory experiments designed to test alternative hypotheses: (i) Maculinea rebeli caterpillars provide a beneficial source of sugar in return for being tended by Myrmica workers; (ii) Maculinea rebeli harms its host by stressing the workers by competing for available sugar. Comparisons were made of Myrmica worker fitness after 90–450 days under all possible combinations of three experimental treatments: ±M. rebeli caterpillars, ± sucrose and ± ant brood. Caterpillars always reduced the survival of both ant workers and their larvae, even when sugar was not provided, suggesting that M. rebeli is wholly parasitic on all stages in its host colony. The results also confirmed the importance of sucrose in the diet of Myrmica, and showed that M. rebeli caterpillars which eat ant brood to supplement their normal trophallactic feeding by workers develop more quickly ‐ but have the same survival and pupal weights – as caterpillars that are fed solely by worker ants.