Feeding behaviour,midgut distension and ovarian development in Phlebotomus papatasi (Diptera: Psychodidae)

Phlebotomus papatasi females were fed through membranes or from cotton wool soaked in blood, water, sucrose or sodium chloride solutions. In membrane-fed flies, all diets were routed to the midgut and not to the crop. Following the meals that went to the midgut, females showed ovarian development at least 3 times greater than in sucrose-fed, autogenous control flies. Neither small quantities of water arriving in the midgut following drinking from soaked cotton wool, nor piercing of a membrane without feeding, stimulated ovarian development. Flies exhibited different feeding behaviour namely, blood feeding, sugar feeding, and water drinking. The blood-feeding behaviour was typical of flies ingesting any of the experimental diets through membranes, or blood or saline from cotton wool. The other two types of behaviour were observed in flies which fed from soaked cotton wool. The type of behaviour was characterized by the depth of penetration of the mouthparts into the substrate, the deployment of the palps and the degree of contact between the palps and the surface. It is suggested that the stimuli which control the routing of meals to the crop or to the midgut are derived from these types of behaviour.     

Rate and diel periodicity of pheromone emission from female gypsy moths, (Lymantria dispar) determined with a glass-adsorption collection system

The rate of pheromone emission from wild and laboratory-reared gypsy moth (Lymantria dispar) (Lepidoptera: Lymantriidae) virgin females was determined with an all-glass aeration apparatus. This device incorporated a bed of 1-mm glass beads to extract entrained pheromone from the air flowing over the protruded gland. The temporal pattern of emission was established by monitoring individual females after eclosion for 24 consecutive 2-hr intervals.At a constant 24°C, both wild and laboratory females exhibited a similar diel periodicity of pheromone emission. The mean release rate increased after onset of photophase, generally attained maximal levels between 1600 and 2200 hr and declined during scotophase. Pheromone was released continuously and the mean daily emission increased with age for both wild and laboratory moths. The mean emission rate over the 48-hr monitoring interval was $\text{15.4 ng}\text{2 hr}$ for wild females vs $\text{14.7 ng}\text{2 hr}$ for laboratory moths. The peak emission from 2-day-old laboratory moths was ca.$\text{28 ng}\text{2 hr}$ compared with the ca.$\text{25 ng}\text{2 hr}$ released by their wild counterparts.The calling periodicity of laboratory females was determined at a constant 24°C and under a natural temperature rhythm. At 24°C, the proportion of females calling exceeded 45% throughout the diel period, whereas under the temperature rhythm, calling was virtually eliminated by temperatures below 15°C, indicating that temperature acts as an exogenous cue to modify the expression of the calling rhythm and thus potentially the periodicity of pheromone emission.     

The aggregation-attachment pheromone of the tropical bont tick Amblyomma variegatum Fabricius (Acari,Ixodidae): Isolation,identification and action of its components

Combining a new in vitro bioassay with the analytical method capillary gas chromatography-mass spectrometry, the aggregation-attachment pheromone produced by fed males of the tropical bont tick Amblyomma variegatum was shown to consist of o-nitrophenol, methyl salicylate and pelargonic acid in the approximate amounts of 2/1/8 × 10^?6 g/tick. A synthetic pheromone blend composed of those three volatile compounds evoked an aggregation response in unfed males and females in a bioassay comparable to the response to a natural pheromone source. Of the individual components. only o-nitrophenol induced a significant, although not complete aggregation response. Methyl salicylate and pelargonic acid contribute to complete pheromone activity, but induce no aggregation response at all, when offered separately.     

Electrophysiological basis for the behavioural response of male and female Trichoplusia ni to synthetic female pheromone

Electroantennogram (EAG) studies demonstrated that antennae of both male and female Trichoplusia ni have: (1) receptor-neurones sensitive to female pheromone, (2) a low response threshold, (3) an identical mean-percentage EAG curve over a broad concentration range of pheromone, and (4) a similar absolute recovery interval from adaptation to pheromonal stimulation. These factors suggest that antennae of male and female T. ni have homologous and homogeneous acceptor sites for the female pheromone. Pheromonal stimulation of female antennae elicited EAGs with only 25% of the amplitude of those elicited in males.     

A reinvestigation of the role of (E)-2-hexenal in female calling behaviour of the polyphemus moth (Antheraea polyphemus)

Calling periodicities in the saturniid moth Antheraea polyphemus were similar in virgin females that were intact, intact and exposed to (E)-2-hexenal and antennectomised. Virgin females and antennectomised virgin females were of comparable attractiveness to males in the field.     

Detection, identification and molecular typing of Leishmania major in Phlebotomus papatasi from a focus of zoonotic cutaneous leishmaniasis in central of Iran

Leishmania major is the causative agent and Phlebotomus papatasi is the main vector of rural zoonotic cutaneous leishmaniasis (ZCL) in Iran and elsewhere. Nested PCR protocols were used to amplify a region of the ribosomal RNA amplicon of Leishmania (ITS1-5.8S rRNA gene) in female P. papatasi. In the current investigation, L. major was found in Natanz, Isfahan province in centre of Iran, in a focus of rural ZCL. Ten (1.8%) out of 549 female P. papatasi was found to be infected with L. major based on the PCR detection and sequencing of parasite ITS-rDNA.Nine (1.8%) out of 498 female P. papatasi infected with L. major came from animal shelters, inside houses and yards. And one (1.9%) out of 51 female P. papatasi infected with L. major came from gerbil borrows. Infection rates were higher for females containing red blood meals, large eggs (semi-mature and mature) than for those without either blood meals or eggs. From the 10 infections detected three different haplotypes of L. major were identified. Two haplotypes were found to be novel. The other haplotypes of L. major was found to be identical to that of isolates of L. major from Iran and in elsewhere using GenBank data. Comparisons of infection rates between habitats will be inaccurate when the proportions of blood-fed and gravid flies differ among sandfly samples.     

Biosynthesis of contact sex pheromone in the female tsetse fly, Glossina morsitans morsitans Westwood

Injection of [2,3 ¹⁴C] sodium succinate into recently emerged, unfed females of Glossina morsitans morsitans resulted in incorporation of radiolabel mainly into surface cuticular alkanes. In vivo experiments with intact flies showed that the distribution of labelled alkanes depended on fly mobility, the legs of unrestrained flies possessing proportionately larger amounts of radioactive hydrocarbon material than those of flies whose legs were tied together with a silk suture. The heads of both restrained and unrestrained flies contained proportionately more material per unit surface area than did any other body part. However, ablation experiments and in vitro incubation showed that the most active incorporation of label into alkanes occurred in the abdomen and that all dorsal abdominal segments were equally active. The ventral abdomen also incorporated label into cuticular alkanes in vitro, but other body parts were apparently less able to do so. The sex pheromone of G. m. morsitans is a trimethyl-substituted alkane, the labelling of which appeared to be in proportion to the relative abundance of its methyl groups among those of the other alkanes of the cuticle following injection of either intact or legless flies. Hence it is proposed that sex pheromone is synthesized along with other cuticular alkanes mainly by cells closely associated with the abdominal cuticle of females and that it is spread over the external surface both by diffusion and by grooming which leads to accumulations of hydrocarbon material on the legs.     

Determination of the site of pheromone emission in the virgin females Culicoides nubeculosus Meigen (Diptera: Ceratopogonidae)

The zone of emission of the sex pheromone from the body of Culicoides nubeculosus was investigated. The amount of pheromone emitted was evaluated by counting the number of matings between males and females exposed to a flow of air coming from a chamber containing virgin females. The number of matings is higher than that recorded when the air flow comes from an empty chamber (control). Three parts of the body were examined: head, thorax and abdomen. Each part was studied by neutralizing the effect of the others. The head was neutralized by decapitation and the females continued to emit pheromone. The head is, therefore, not indispensible for pheromone emission. The roles of the thorax and abdomen were studied by coating these with paraffin wax. When the thorax is coated, pheromone emission continues, but when the abdomen is coated, it stops. It appears that the abdomen alone is responsible for emission of the sex pheromone.     

Endogenous and exogenous factors affecting periodicities of female calling and male sex pheromone response in Grapholitha molesta (Busck)

In Grapholitha molesta periodicities of both female calling and male response to sex pheromone by wing fanning while walking were determined in part by circadian rhythms. The lights-on photoperiodic cue was at least partly responsible for setting the phase of the female calling rhythm. Absolute temperature levels and not necessarily a decrease in temperature modified the timing of calling; there were both high and low thresholds of temperature and, at particular photoperiod times, a temperature range optimal for calling. When the previous performance of calling was prevented by subthreshold temperatures, calling during the next period commenced earlier if temperatures were favourable. Thus, the previous performance of calling may establish a refractory period, or temperature decrease may act as a cue resetting the phase of the calling rhythm. The ability to use both an endogenous clock and exogenous temperature cues to synchronize sexual activity appears adaptive for a temperate zone insect whose multiple generations are exposed to both long periods of favourable climatic conditions in summer and harsh, unpredictable conditions in spring or fall.     

Ultrastructural cytochemistry of the sex pheromone glands of Lutzomyia cruzi male sand flies (Diptera: Psychodidae: Phlebotominae)

The sex pheromone glands of Lutzomyia cruzi male sand flies (Diptera: Psychodidae) were analyzed by cytochemical techniques. In adult males, the epithelium at the fourth abdominal tergite is modified into a glandular epithelium, with large columnar gland cells located side by side. The gland cell cytoplasm contains a large number of mitochondria and peroxisomes, the latter with positive (electron-dense) reaction for catalase, a typical peroxisomal enzyme marker. The gland cell cytoplasm also contains a central vacuolated area, with a large number of electron-lucent vacuoles, not limited by a unit membrane. In well-preserved preparations such vacuoles present a homogenous and slightly electron-dense content, typical of lipid droplets. Indeed, incubation of the tergites with imidazole-buffered osmium tetroxide (to detect lipids) resulted in positive reaction in these vacuoles, as well as in between the microvilli of the gland cells. Use of the osmium–potassium iodide (Os–KI) technique allowed to demonstrate the presence of several endoplasmic reticulum (ER) profiles, as expected in secretory cells. Our data suggest that ER, lipid droplets and peroxisomes are involved in the sand fly pheromone biosynthesis.     

Physiology and morphology of the larval sexual pheromone-sensitive neurones in the olfactory lobe of the cockroach, Periplaneta americana

Deutocerebral neurones of larval and adult male cockroaches responding to the female pheromone and its components were recorded extracellularly. No responses to the female pheromone were found in larvae younger than about 10th instar. However, two groups of pheromone-sensitive neurones were recorded in males from 10th instar onwards as in adults. A correlation and factor analysis based on the cells' responses to the pheromone stimuli was used to test the correspondence of these larval and adult cell groups. The recorded larval pheromone-sensitive neurones were stained with cobalt and their morphology compared with that of the adult neurones.     

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.

     

Identification by GC-EAD of the two-component trail-following pheromone of Prorhinotermes simplex (Isoptera, Rhinotermitidae, Prorhinotermitinae)

GC/MS analysis confirmed that neocembrene is the major component of the trail pheromone in the three species of the termite genus Prorhinotermes (P. simplex, P. canalifrons, P. inopinatus). In addition, EAG and GC-EAD experiments with P. simplex strongly suggest that dodecatrienol is a quantitatively minor component but a qualitatively important component of this trail pheromone. Trail-following bioassays confirmed the two-component nature of the trail pheromone. This is the first report of the use of the GC-EAD for the identification of trail pheromone in termites. These original results underline once again the special phylogenetic status of the Prorhinotermitinae among Rhinotermitidae.     

Two 2-arylbenzofurans as insect feeding deterrents from sainfoin (Onobrychis viciifolia)

Two 2-arylbenzofurans have been isolated as insect feeding deterrents from the roots of the forage legume, sainfoin. They have been identified as 2-(2'-hydroxy-4'-methoxyphenyl)-5-hydroxy-6-methoxybenzofuran (sainfuran) and 2-(2',4'-dimethoxyphenyl)-5-hydroxy-6-methoxybenzofuran (methylsainfuran). Their synthesis is described.     

Aggregation pheromone in Sternechus subsignatus (Coleoptera: Curculionidae): olfactory behaviour and temporal pattern of emission

The Brazilian soybean stalk weevil, Sternechus subsignatus Boehman (Coleoptera: Curculionidae), is a pest of economic importance in many regions of Brazil. Volatiles from both sexes of S. subsignatus were collected by aeration and the behavioural response of males and females was evaluated using a Y‐olfactometer. The results obtained demonstrate that the communication in S. subsignatus is mediated by aggregation pheromone as both sexes were attracted to host plant (HP) volatiles, and this attraction was increased by the addition of male volatiles. At least five male‐specific compounds (1–5) were detected in the chromatographic analysis, providing chemical support to the behavioural data. Release of these volatiles is dependent on the presence of the HP as the amount of compounds differs significantly when volatiles are collected from weevils with or without access to food. The release takes place mainly during photophase, showing a peak between 4 and 6 h after its beginning, which is also a peak of the insect activity in the field. Studies are underway to elucidate the structures of these putative aggregation pheromone components, in order to evaluate their biological activity under laboratory and field conditions.     

Modulation of sex pheromone perception in female moths of the eastern spruce budworm, Choristoneura fumiferana by altosid

Topical application of 10 μg of Altosid, a juvenile hormone analogue to adult female moths of the spruce budworm significantly reduced their electroantennogram responses to their own synthetic female sex pheromone provided the EAG recordings were performed at least 10–15 hr after JHA treatment. Newly emerged moths were more sensitive to JHA treatment than older moths. Acetone-treated moths (control) showed an increase in EAG response to sex pheromone with increasing age. These age related responses of moths to their sex pheromone and their reduction by Altosid treatment are discussed in terms of endogenous JH titres.     

Aggregation pheromone activity of the female sex pheromone, beta-acaridial, in Caloglyphus polyphyllae (Acari: Acaridae)

Caloglyphus (= Sancasania) polyphyllae discharges from a pair of opisthonotal glands a characteristic set of volatiles, i.e. three monoterpenes and seven hydrocarbons. Among them, beta-acaridial, which is known as the female sex pheromone of the species and has antifungal activity, was newly identified as the aggregation pheromone for unfeeding and unmating mites. Feeding mites, however, exhibited sexually aroused behavior instead of the tendency to cluster when exposed to beta-acaridial. This is the first example of the compound demonstrating two pheromone functions depending upon the circumstances faced by the mites.     

Effect of age and mating on pheromone production in the female olive fruit fly, Dacus oleae (Gmel.)

Virgin female olive fruit flies began producing sex pheromone on the third day after emergence. Production of sex pheromone appears to be cyclical with peaks of production recurring at about 10-day intervals, each peak lasting 2–3 days. As the female ages, the quantity of sex pheromone produced during the period of high pheromone production decreases, but it is always higher than the quantity present in the pheromone gland during the rest of female life.Mated females produced less sex pheromone the first 10 days after mating which then increased to near the same level of that in virgin females.     

Patterns of biosynthesis and accumulation of hydrocarbons and contact sex pheromone in the female german cockroach,Blattella germanica

De novo synthesis of contact female sex pheromone and hydrocarbons in Blattella germanica was examined using short in vivo incubations. Accumulation of pheromone on the epicuticular surface and the internal pheromone titer were related to age-specific changes in hydrocarbon synthesis and accumulation in normal and allatectomized females. The incorporation of radiolabel from [1-¹⁴C]propionate into the cuticular methyl ketone pheromone fraction was positively related to corpora allata activity during two gonotrophic cycles. During peak pheromone production the total internal lipid fraction contained greater titers of pheromone than the cuticular surface, and it too exhibited a cycle internally, preceding the rise in external pheromone. This suggests that synthesis and accumulation of pheromone internally are followed by transport of pheromone to the epicuticular surface where it accumulates. Radiolabel was incorporated efficiently into both cuticular and internal hydrocarbons after the imaginal molt and until the peak of pheromone synthesis, but it declined to lower levels before ovulation and throughout pregnancy. The internal hydrocarbon titer decreased 58% after oviposition, suggesting deposition in the egg case. It remained relatively unchanged during pregnancy and increased again during the second gonotrophic cycle. In allatectomized females, hydrocarbon synthesis was reduced relative to control females until oviposition in the latter. However, subsequent rates of hydrocarbon synthesis in allatectomized females (without oothecae) exceeded the rates in sham-operated females (with oothecae). In the absence of ovarian uptake of hydrocarbons, the internal titer increased without the decline found in control females at oviposition. As internal hydrocarbons increased, so did cuticular hydrocarbons and both internal and cuticular methyl ketone pheromones. These patterns corresponded well with feeding patterns in sham-operated and allatectomized females, suggesting that pheromone production is normally regulated by stage-specific feeding-induced hydrocarbon synthesis (precursor accumulation internally) and juvenile hormoneinduced conversion of hydrocarbon to pheromone. They also suggest that both the cuticle and the ovaries might be target sites for hydrocarbon and possibly methyl ketone deposition. © 1994 Wiley-Liss, Inc.