The role of larval food resources and adult movement in the population dynamics of the orange-tip butterfly (Anthocharis cardamines)

Numbers of the orange-tip butterfly were recorded on a permanent transect in Monks Wood National Nature Reserve between 1982 and 1993, together with numbers of its only larval food plant in the wood, Cardamine pratensis. Females of the butterfly lay their eggs on the newly opened flower heads of Cardamine and the larvae feed on the developing seed pods. They are extremely selective in their choice of plant for egg laying, choosing mainly large flower heads growing in open sunny locations. Larval survival is greatly reduced if the flower head is more than 8 days old at the time of egg laying, because the seed pods become too tough for feeding. Earlier studies showed that only one larva can survive on a flower head, because larvae are cannibalistic, but females tend to avoid plants carrying more than one egg, in response to an oviposition-deterring pheromone laid down at the time of egg laying. The numbers of flower heads of Cardamine fluctuate enormously between years, and the numbers of eggs follow these closely. There is a strong correlation between number of eggs laid and the availability of suitable flower heads, and this correlation was shown to be real and causal by the experimental provision of extra flower heads, which resulted in more eggs, laid over an extended period of oviposition. The main causes of mortality of the butterfly's young stages were egg infertility, cannibalism, predation, starvation, the grazing of flower heads by deer, and possibly the failure of the newly hatched larvae to feed adequately. Adult numbers were only weakly correlated with the numbers of young stages in the wood, and there appears to be a considerable amount of movement by the butterfly through the wood and surrounding farmland. Received: 8 October 1996 / Accepted: 3 April 1997     

The population biology of the Orange Tip butterfly Anthocharis cardamines in Britain

ABSTRACT.

• 1 The population biology of Anthocharis cardamines (L.) is described and shown to vary with locality. Southern and Western populations emerge earlier than Northern ones, but Western and Northern populations occupy similar, wetter habitats and are associated primarily with Cardamine pratensis (L.). Southern populations are recorded mostly from Alliaria petiolata (Bieb.).
• 2 Studies on egg and larval survival indicate that host plant-induced death and parasitization by a tachinid are important mortality factors. However, a key-factor analysis on one population indicates that the major determinant of population size may be the number of eggs laid by ovipositing females, itself dependent upon weather during the oviposition period. Populations in different localities do show similar trends in abundance, corroborating the effect of weather.
• 3 Human effects on distribution and abundance are discussed, and some conservation strategies suggested.

     

Host plant conspicuousness and the distribution of eggs and larvae in the butterfly,Anthocharis scolymus (Lepidoptera: Pieridae)

We investigated how the distribution pattern of eggs and larval on the host plant, Turritus glabra, was influenced by the oviposition behavior of the pierid butterfly Anthocharis scolymus. Females searched for the host plants visually and they frequently approached taller host plants with sparse surrounding vegetation. After encountering host plants, oviposition behavior of females was independent of host plant characteristics such as height, density, and type of surrounding vegetation. A female laid eggs singly on a host plants. Most females appeared to lay their eggs regardless of the presense of eggs on the host plant. Consequently egg and larva tended to be abundant on conspicuous host plants as measured by height or relative isolation from other plants. However, overcrowding of eggs on an individual host decreased the survival rate of larvae.     

The 'edgeeffect' in butterfly oviposition: causality in Anthocharis cardarnines and related species

Abstract. 1. An 'edge-effect', where outlying host plants receive proportionately most attention from insect herbivores, is described from the literature, and from data on Anthochoris cardamines (L.), in northern England.
2. Six hypotheses are examined as explanations for the effect in A.curdamines . Four are shown to be refuted by studies on female behaviour and the survival of larvae.
3. It is argued that the 'edge-effect' comes about due to two or more aspects of the searching behaviour of females. The effect may be seen as an outcome of behaviour adapted to searching for host plants of low density.     

Effects of time-dependent intraspecific competition on offspring survival in the butterfly, Anthocharis scolymus (L.) (Lepidoptera: Pieridae)

Effects of mothers' eclosion and oviposition timing on the survival of their offspring in the pierid butterfly Anthocharis scolymus (L.) was examined. I recorded the performance of individual eggs and larvae that differed in their mother's eclosion and oviposition timing in a natural population, where A. scolymus feeds on Turritis glabra (L.) Bernh. Eggs laid early in the season, and larvae emerging from these eggs, had higher survival than eggs laid later, and larvae emerging from eggs that were laid later in the season, the causal factor being egg cannibalism by larvae on the same host plant. Logistic regression showed that females eclosing early in the season had higher offspring survival than females eclosing later. I conclude that optimal timing of adult eclosion in A. scolymus is a trade-off between eclosing early with associated higher offspring survival but lower egg-laying rate, and eclosing later with associated lower offspring survival but higher egg-laying rate. Received: 4 August 1997 / Accepted: 19 October 1997     

Deposition and longevity of oviposition-deterring pheromone in the cabbage seed weevil

Abstract The cabbage seed weevil ( Ceutorhynchus assimilis Payk.) lays eggs singly into pods of oilseed rape ( Brassica napus L.) through punctures bored with the mouthparts, preferring pods not recently used for oviposition. A simple new choice test has been used to test individual components of egg-laying behaviour for their effect on oviposition site selection. It is confirmed that an oviposition-deterring pheromone (ODP) is deposited during abdomen brushing of the pod which follows egg-laying. Neither pin punctures, weevil feeding punctures, oviposition punctures nor eggs had any deterrent effect. Pods walked on by female weevils were not avoided by those laying eggs. Observations suggest that the ODP is sensed by contact chemoreceptors on the antennae. The deterrent effect lasted only 1–2 h. The implications of these findings on the adaptive significance of the pheromone and its possible use in pest control are discussed.     

Site of production of an oviposition-deterring pheromone component in Rhagoletis pomonella flies

Using behavioural and electrophysiological assay techniques, we identified the posterior half of the midgut as being a principal site of production of a major component of the oviposition-deterring, fruit-marking pheromone of female Rhagoletis pomonella flies. Following secretion into, and accumulation in, the gut lumen, this component is released, together with other gut contents, in the marking trail deposited during dragging of the ovipositor on the fruit surface after egg-laying, as well as in the faeces. Other components of the pheromone may be produced elsewhere.     

Evolution of cannibalism and female's response to oviposition-deterring pheromone in aphidophagous predators

1.  Egg cannibalism by larvae is common in Coccinellidae and is known to be advantageous for the cannibals. Furthermore, larvae of aphidophagous ladybirds usually produce an oviposition-deterring pheromone (ODP), which inhibits oviposition by adult females. It has been proposed that the response to ODP has evolved because of the high costs of cannibalism. However, this has never been formally proved.
2.  In this paper, we study the theoretical evolution of this system. We first look at the conditions under which cannibalism and the response to ODP can evolve. Subsequently, we examine the occurrence of polymorphism both in the production of larval tracks and in the sensitivity of females to specific pheromones.
3.  The models predict that the amount of cannibalism should not depend on prey density and that evolution should lead to a continuous increase in cannibalism, and consequently larvae should always cannibalize eggs when possible. In response to the cost of cannibalism, ODP recognition can evolve, so that females avoid laying eggs in patches of prey already occupied by conspecific larvae. The result is an arms race between larvae and adult females, which favours a diversification of ODP pheromones. Our models show that: (i) females should be able to recognize mixtures of hydrocarbons rather than a single molecule; and (ii) females should be more sensitive to the tracks of their own offspring than those of non-related larvae.     

Response of the sandfly Lutzomyia longipalpis to an oviposition pheromone associated with conspecific eggs

Response of female Lutzomyia longipalpis Lutz & Neiva (Diptera: Psychodidae) to an oviposition attractant and/or stimulant associated with conspecific eggs was investigated in the laboratory. Females of two populations laid significantly higher mean number of eggs on sites with 160 eggs already present than on bare control sites. This response was lost when eggs placed on test sites were previously washed in organic solvents and distilled water. Age of eggs placed on test sites, 1-6 days after being laid, did not seem to affect the oviposition response of the females. Comparing effects of different numbers of eggs, positive responses were obtained when 80, 160 or 320 eggs were placed on test sites. No significant differences between mean egg numbers laid on test sites and controls were detected when batches of only 20 or 40 eggs were used.     

Correlation between glycerolipids and pheromone aldehydes in the sex pheromone gland of female tobacco hornworm moths,Manduca sexta (L.)

Analysis by TLC and HPLC revealed that the triacylglycerols comprise the most abundant lipid class in the sex pheromone glands of Manduca sexta females. Also, conjugated olefinic acyl analogs of the major pheromone aldehydes occur principally in the triacylglycerols. The amount of triacylglycerols with conjugated diene acyl moieties significantly decreased when the period of pheromone production was extended by 7 h beyond the normal period of pheromone production by 3 injections of pheromone biosynthesis activating neuropeptide (PBAN) at 3 h intervals. This decrease indicates that the triacylglycerols stored in the gland may serve as major sources of pheromone precursors in the biosynthesis of the sex pheromone aldehydes. Furthermore, analysis of pheromone aldehydes and triacylglycerols in the gland from moths treated with PBAN showed that the proportions of the triacylglycerols with conjugated diene moieties were closely correlated with the proportions of aldehydes found in the same gland. This correlation suggests that the proportions of fatty acids bound to certain triacylglycerols regulates the proportions of aldehydes in biosynthesis of the pheromone blend in M. sexta. © 1995 Wiley-Liss, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America.

     

Possible Age-Dependent Variation in Egg-Loaded Host Selectivity of the Pierid Butterfly, Anthocharis scolymus (Lepidoptera: Pieridae): A Field Observation

To understand better the effects of age on host selection through conspecific egg detection by Anthocharis scolymus females, field observations were performed at a graveyard where the insect population was isolated and the host plant was limited to the cruciferous plant, Turritis glabra. We chased females and recorded their oviposition behaviors and the conditions of plants which females approached. Older females tended to avoid ovipositing on egg-loaded host plants and selectively laid eggs on nonloaded host plants. This result was not confounded by other factors such as seasonality, air temperature, plant height, plant phenological stage, surrounding vegetation, host plant density, and extent of plant damage. We discuss the possibility that females make an oviposition decision on how to lay their limited number of eggs during their remaining lifetime.     

Persistence of the oviposition-deterring pheromone inChrysopa oculata (Neur.: Chrysopidae)

Paper previously exposed for short periods to first instar larvae ofChrysopa oculata Say (Neur.: Chrysopidae) deters conspecific females from ovipositing. The deterrent effect was not reduced by keeping the substrates at temperatures of up to 140°C for one hour. The oviposition-deterring pheromone is volatile. If contaminated substrates were kept in the open air for 3–4 weeks they no longer deterred females from ovipositing. However, the deterrent effect did not decrease significantly when the substrates were kept for 20 weeks in small Petri dishes. Clean paper substrates enclosed for one day above glass previously walked over by larvae also deterred females from ovipositing.     

Evidence for a host-marking pheromone in Chaetorellia australis

Experiments and observations on the oviposition behavior of Chaetorellia australis Hering (Diptera, Tephritidae) females, caged in the laboratory with their natural oviposition substrates, floral buds of the yellow starthistle (YST) Centaurea solstitialis L. and Centaurea cyanus L. (Asteraceae: Cardueae) revealed that females of that species deposit a contact host-marking pheromone immediately after oviposition by dragging their extended ovipositor over the floral bud surface. The function of this pheromone is the prevention of repeated oviposition in already infested oviposition sites. Apparently it also plays a role in sexual behavior by functioning as a male arrestant. The pheromone was found to be soluble in water but insoluble in methanol, ethanol, diethyl ether and acetone. Under laboratory conditions, its effectiveness persisted for at least 10 days. By preventing oviposition on already infested buds the pheromone apparently contributes to uniform egg dispersion among available resources for larval development. By functioning as a male arrestant, which causes aggregations of males on places visited frequently by females such as the floral buds of host plants, it also contributes to overall fertility by facilitating encounters of the sexes. The potential practical application for biocontrol of the YST through introducing and releasing C. australis flies into areas infested by the weed is discussed.

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Zusammenfassung Versuche und Beobachtungen über das Eiablageverhalten von im Labor mit ihren natürlichen Eiablagesubstraten, d.h. Blütenknospen von Centaurea solstitialis L. und Centaurea cyanus L. (Asteraceae: Cardueae) gehaltenen Chaetorellia australis Hering (Diptera: Tephritidae) zeigten, dass C. australis Weibchen sofort nach der Eiablage die Oberfläche der Blütenknospe mit einem eiablageverhindernden Pheromon markieren, indem sie ihren ausgestellten Ovipositor über die Oberfläche der Blütenknospe ziehen. Das Pheromon, das auch als Männchen-Arrestans wirkt, ist wasserlöslich, jedoch unlöslich in Methanol, Äthanol, Diethyläther und Aceton. Unter Laborbedingungen hält seine Wirkung mindestens 10 Tage an. Da das Pheromon die Eiablage an bereits infestierten Blütenknospen verhindert, trägt es zu einer gleichmässigen Eiverteilung in den für die Larvenentwicklung zur Verfügung stehenden Futtequellen bei. Als Männchen arretierendes Pheromon führt es zur Aggregation von Männchen an den Blütenknospen, die oft von Weibchen besucht werden und versichert somit eine hohe Fertilität, indem es das Zusammentreffen der Geschlechter erleichtert. Die praktische Anwendung der Ergebnisse für die biologische Bekämpfung von Centaurea solstitialis durch Einfuhr und Freilassung von C. australis in die mit dem Unkraut verseuchten Gebiete wird diskutiert.

     

Venom as an interspecific sex pheromone, and species recognition by a cuticular pheromone in Paper Wasps (Polistes, Hymenoptera: Vespidae)

ABSTRACT. The venoms of Polistes fuscatus (subspecies fuscatus) (F.) and P. exclamans Viereck from sympatric populations in North Carolina, U.S.A., contain a pheromone which attracts males and stimulates sexual behaviour in both conspecific and heterospecific males. Males of P. fuscatus (subspecies variatus Cresson), a subspecies from Wisconsin, respond to venom of P. fuscatus fuscatus, P. exclamans, and Vespula maculifrons (Buysson) from North Carolina, although the levels of response to P. exclamans and V. maculifrons venom are less than that to P. fuscatus variatus venom.
Caged Wisconsin P. fuscafus males do not attempt to mate with P. exclamans females, but will attempt to mate with conspecifics. A series of bioassays indicates that males discriminate between females of P. fuscatus and P. exclamans on the basis of chemical, rather than behavioural or visual cues. The venom apparently is not important in species recognition. Instead, the results of two sets of bioassays suggest that species recognition is mediated by a surface pheromone on the cuticle of females.     

Isolation of oviposition pheromone from the eggs of the sandfly Lutzomyia longipalpis

Abstract. Semiochemical components of eggs of the sandfly Lutzomyia longipalpis (Diptera: Psychodidae) were separated by high performance liquid chromatography. HPLC fractions were examined quantitatively and qualitatively by gas chromatography (GC). A bioassay was used to determine the oviposition attraction of gravid L. longipalpis to each of the fractions separately and a peak responsible for the semiochemical activity was identified. Gravid flies were placed in individual oviposition tubes to determine if the peak of interest was an oviposition stimulant. The active semiochemical fraction attracted gravid flies for oviposition. Furthermore, egg laying was enhanced: gravid flies exposed to the pheromone oviposited earlier and laid more eggs than control flies. GC analysis indicated that 1200 eggs (2 days old) gave a yield of 12.75 ug of active pheromone. This fraction had similar HPLC and GC retention times to caryophyllene oxide, suggesting comparable polarity and molecular weight.     

Effect of marking pheromone on clutch size in the Mediterranean fruit fly

Abstract Using acridine orange to selectively stain eggs, we showed that wild-collected female Mediterranean fruit flies (Ceratitis capitata Wiedemann) laid fewer eggs per clutch in fruit previously infested with eggs than in uninfested fruit. This effect is apparently attributable to marking pheromone deposited by females after oviposition: clutch size on fruit infested with eggs but free of marking pheromone was not statistically different from that on uninfested fruit. Clutch size on uninfested fruit on which marking pheromone was artificially transferred was significantly lower than that on uninfested and untreated fruit. Marking pheromone had a comparable though not statistically significant effect on the clutch size of females originating from a strain maintained in the laboratory for several hundred generations.     

Effect of Mating Disruption on Reproductive Behavior in the European Pine Sawfly, Neodiprion sertifer (Hymenoptera: Diprionidae)

Females of the European pine sawfly, Neodiprion sertifer (Geoffr.) (Hymenoptera: Diprionidae), were released and observed inside and outside (=control) of areas treated with their sex pheromone for the purpose of mating disruption. In 1992 and 1993, respectively, 0 and 2.5% of the females were observed mating in the pheromone treated area during the first day, compared with 28 and 26% in the control area. Of the females that mated, approximately 50% stayed on their twigs and oviposited, while the remaining 50% disappeared. Significantly more females disappeared from their twigs inside the treated area compared to the control area in both years. No difference was found in the proportion of unmated females ovipositing (2–12%) between the treated and the control area. Predation was responsible for much of the disappearance, but deliberate dispersal was also noted. Mating and dispersal in female N. sertifer are discussed in relation to population density and overall fitness.     

Characterization of oxidase(s) associated with the sex pheromone gland in Manduca sexta (L.) females

An oxidase that converts primary aliphatic alcohols into aldehydes was discovered in the cuticle of the sex pheromone gland and in the papillae anales on the tip of the abdomen of Manduca sexta females. Oxidase activity was not found in the epidermal cells of the pheromone gland where fatty acid precursors of the pheromonal aldehydes are found. This oxidase requires oxygen and water to function and appears to have a rather broad substrate specificity. The activity of the oxidase is reduced by the application of piperonyl butoxide, which also interferes with the PBAN induced production of the natural pheromone aldehydes. However, endogenous alcohols cannot be found in the pheromone gland. Thus, it is not yet clear whether or not the oxidase is involved in the terminal step of biosynthesis of the pheromone aldehydes in M. sexta females. © Wiley-Liss, Inc.

1 This article is a U.S. Government work and, a such, is in the public domain in the United States of America.

     

Evidence of protease in the saliva of the butterfly Heliconius melpomene (L.) (Nymphalidae, Lepidoptera)

Butterflies of the genus Heliconius are well known for their peculiar habits of utilizing pollen as a source of amino acids. Saliva plays a major role in the process of extracting amino acids and proteins from the pollen grains. In this investigation, we obtained samples of saliva from adult Heliconius melpomene by placing pumpkin pollen or fine glass-beads on the proboscis, which stimulates the butterflies to release saliva. Proteolytic activity was determined in the saliva by an insoluble protein-dye that turns blue when cleaved by proteases. Its extinction value was measured with a spectrophotometer at 595 nm. Both the saliva sampled with pollen and the saliva obtained from inert glass-beads exhibit proteolytic activity demonstrating that the saliva contains proteases. The proteolytic activity of the pollen/saliva samples was higher than that of the glass-bead/saliva samples, which we attribute to the stimulating effects of pollen, such as taste, smell, and texture, and not to proteases which might have been liberated from the pollen. This is indicated by the fact that pollen samples without saliva showed only a negligible indication for proteolytic activity. In general, females exhibit higher proteolytic activities than males, presumably due to their greater amino acid investment in reproduction. We present here first evidence for the existence of proteases in the saliva of a butterfly species and suggest that these enzymes are crucial for the use of amino acids and proteins from pollen in Heliconius butterflies.     

Evidence for a female‐produced,long range pheromone of Anoplophora glabripennis (Coleoptera: Cerambycidae)

Abstract Volatiles from female Asian longhorned beetle (ALB), Anoplophora glabripennis, were evaluated as candidate sex pheromone components. Previous studies on ALB have revealed several antennally active compounds from virgin females; however the origins and activity of these compounds were not apparent and require further investigation. We tested the hypothesis that one or more of the ALB contact sex pheromones is a precursor that undergoes abiotic oxidation to yield volatile pheromone components, and evaluated the activity of these compounds using laboratory and field bioassays. Gas chromatography coupled electroantennography detection (GC‐EAD) analysis indicated the presence of three antennally active aldehydes (heptanal, nonanal, and hexadecanal) in female cuticular extracts exposed to ozone or UV and visible light. In laboratory bioassays using a Y‐tube olfactometer, males were preferentially attracted to ozonized female body washes over crude body washes. Similarly, synthetic formulations of these compounds were preferred over controls in the olfactometer. Field trapping experiments conducted from 2006 to 2008 in Ningxia, China showed that synthetic lures of the three aldehydes formulated in a ratio simulating that of virgin females attracted more beetles compared to controls, and that combinations of these aldehydes, linalool oxide, and host kairomones captured more beetles than controls, and captured significantly more males.