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  • 1
    ISSN: 1423-0445
    Keywords: maturation ; pheromone ; volatiles ; anisole ; benzaldehyde ; veratrole ; phenylacetonitrile ; 4-vinylveratrole ; Orthoptera ; Schistocerca gregaria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The accelerating effect of mature males of the desert locust,Schistocerca gregaria, on the maturation of immature male and female conspecifics was confirmed. The onset of sexual activity was found to correlate with yellowing of the male insects. Using the colour as an indicator of maturation, the maturation-hastening effect of an hexane extract from mature males was also confirmed. Likewise, volatiles from mature males placed in the upper storey of a two-chamber bioassay system (no visual or tactile contact possible) and charcoal-trapped volatiles from the mature males also induced accelerated maturation in recipient males placed in the lower storey. GC and GC-MS analysis of volatiles collected from 4-week-old mature males showed the presence of anisole, benzaldehyde, veratrole, phenylacetonitrile and 4-vinylveratrole, roughly at the ratio 4.8:7.0:3.3:79.8:5.0. In addition, guaiacol, phenol, benzoylnitrile, benzyl alcohol and 2-benzoyloxyphenylacetonitrile were present in smaller amounts. These compounds were either absent or found only in trace amounts in the female volatiles. Earlier, we had shown that essentially the same blend collected from younger males (10–20 d old, not yet demonstrating signs of maturation) induced strong aggregation of both sexes of adult desert locusts, suggesting a parsimonious role for the pheromone system: as an adult aggregation signal and as a maturation accelerant in young adults.
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  • 2
    ISSN: 1423-0445
    Keywords: learning behaviour ; green leaf volatiles ; olfactometer ; electroantennogram ; Cruciferae ; Gramineae ; Zygophyllaceae ; Orthoptera ; Acrididae ; Schistocerca gregaria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Gregarious nymphs of the desert locust,Schistocerca gregaria (Forsk.) (Orthoptera: Acrididae) were more attracted to volatiles from mechanically damaged food plants used for rearing than to either the undamaged or damaged food plants not used as diet in Y-tube olfactometer assays. Comparative analysis of the volatile emissions from plants used for rearing and food plants not used for rearing,e.g. Sorghum bicolor, Pennisetum clandestinum, Schouwia thebaica, wheat (Triticum sp., var. ‘Nyangumi’),Zygophyllum simplex, Heliotropium undulatum andTribulus terrestris was carried out by GC, GC-EAD and GC-MS. Significant quantitative and qualitative differences were found in the volatile emissions and olfactory responses of nymphs in GC-EAD assays. Up to 33 compounds were identified in volatiles of the plants of which 9 evoked EAGs. EAG-active components included common green leaf compounds (E)-2-pentenal, (E)-2-hexenal, 4-methyl-3-pentenal, (E)-3-hexenyl acetate, (Z)-3-hexenyl acetate, (Z)-2-hexenyl acetate, (Z)-3-hexen-1-ol and (Z)-2-hexen-1-ol. (Z)-3-Hexenyl butyrate and (Z)-3-hexenyl isovalerate were detected in stimulatory amounts only in the volatiles ofS. thebaica. (E, Z)-2,6-Nonadienal was detected as a component in the volatiles ofT. terrestris and was highly stimulatory. In EAG assays with seven common green leaf volatiles, (Z)-3-hexenyl acetate was most stimulatory while hexanal was the least. No significant differences were recorded between antennal responses of males and females to the tested compounds. These results are discussed with regard to current hypotheses on host plant recognition through detection of their airborne volatiles and the learning behaviour by nymphs ofS. gregaria.
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  • 3
    ISSN: 1573-1561
    Keywords: Chilo partellus ; Lepidoptera ; Pyralidae ; sorghum ; feeding response ; phenolics ; phagostimulant ; 4-hydroxybenzaldehyde ; 4-hydroxybenzoic acid ; 4-hydroxy-3-methoxycinnamic acid ; 3,4-dihydroxycinnamic acid ; 4-hydroxycinnamic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Phagostimulatory responses of third-instar larvae ofChilo Partellus to phenolic components identified in an ethyl acetate extract of the leaf whorls of 3-week-old plants ofSorghum bicolor cultivar IS 18363 were studied in no-choice bioassays. The major components in the extract were identified as 4-hydroxybenzaldehyde and 4-hydroxybenzoic acid, with 4-hydroxy-3-methoxycinnamic acid, 3,4-dihydroxycinnamic acid, and 4-hydroxycinnamic acid present in minor amounts. All but 4-hydroxycinnamic acid were stimulatory at the doses tested. 4-Hydroxybenzaldehyde was more stimulatory than other potential biogenetic analogs. Hydroxybenzoic acids generally elicited greater feeding response than cinnamic acids, and the pattern of oxygen substitution in the benzene ring was related to bioactivity.
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  • 4
    ISSN: 1573-1561
    Keywords: Schistocerca gregaria ; Orthoptera ; Acrididae ; gregarious locusts ; aggregation pheromones ; anisole ; benzaldehyde ; veratrole ; guaiacol ; phenylacetonitrile ; phenol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Six electrophysiologically active aromatic compounds, viz., anisole, benzaldehyde, veratrole, guaiacol, phenylacetonitrile, and phenol, were identified in the volatiles of older-adult male desert locust. Young adults and females of all age groups produced none or only trace quantities of these compounds. Comparison of the aggregation responses of young and older adults to the crude, older-adult, volatile extract and different synthetic blends of the six compounds showed that the aggregation pheromone system of the adult gregarious locust consists of phenylacetonitrile, guaiacol, phenol, and benzaldehyde. Like the crude volatile extract of older males, neither the synthetic blend of the six compounds nor the adult pheromone blend evoked any significant aggregation responses from nymphs. These results confirm our previous report of sexual differentiation in the production of adult aggregation pheromone in the desert locust and of the evidence of two distinct aggregation pheromone systems in the two stages of the insect.
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  • 5
    ISSN: 1573-1561
    Keywords: Schistocerca gregaria ; locusts ; aggregation pheromone ; hexanal ; octanal ; nonanal ; decanal ; hexanoic acid ; octanoic acid ; nonanoic acid ; decanoic acid ; guaiacol ; phenol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Hexanal, octanal, nonanal, decanal, hexanoic acid, octanoic acid, nonanoic acid, and decanoic acid were identified in the volatile emissions from fifth instars ofSchistocerca gregaria by coupled gas chromatography-electroantennography (GC-EAD) detection and coupled GC-mass spectrometry (MS). In laboratory assays, synthetic blends of the eight compounds, with acids and aldehydes tested separately, evoked strong aggregation responses from fifth instars, similar to responses evoked by a crude volatile extract of the nymphs. A nymphal fecal volatile phenolic blend of guaiacol and phenol, which we have previously shown to evoke an aggregative response from different stages of the insect, significantly synergized the activity of the blend of eight compounds, suggesting mutually augmentative roles for nymphal and fecal volatiles in evoking aggregation. These results indicate that the aggregation behavior of gregarious second to fifth instars is modulated by three sets of pheromonal compounds: aldehydes and acids emitted by the nymphs themselves and phenols associated with their feces.
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  • 6
    ISSN: 1573-1561
    Keywords: Schistocerca gregaria ; sexual maturation ; hexanal ; octanal ; nonanal ; decanal ; hexanoic acid ; octanoic acid ; nonanoic acid ; decanoic acid ; guaiacol ; phenol ; pheromone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The effect of the presence of gregarious fifth-instar nymphs on the sexual maturation of newly molted gregarious immature adult males and females of the desert locust S. gregaria was investigated by monitoring color changes (yellowing of body), sexual activity, aggregation–maturation pheromone titers (as measured by phenylacetonitrile levels in males), oocyte length, and oviposition time. Maturation was significantly delayed in adults that were reared together with fifth-instar nymphs (visual, tactile, and chemical signals present) with respect to all parameters measured. Male and female nymphs were equally effective in inducing this delay. Nymphs kept in an upper compartment of two-chamber cages (no visual or tactile contact possible) were similarly effective, but their feces were ineffective, suggesting the mediation of a volatile signal from the nymphs themselves. This was confirmed by examining the effect of volatiles trapped from nymphs and testing synthetic blends of previously identified nymphal aggregation pheromone components (C6, C8–C10 aliphatic aldehydes and acids, guaiacol, and phenol) on the sexual maturation of adults. These and previous studies suggest a dual role for nymphal volatiles as nymphal aggregants and adult maturation retardants, similar to the adult volatiles that are known as adult aggregants and maturation accelerants. The results are discussed in terms of the role of the two pheromone systems in synchronizing maturation of the gregarious adults.
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  • 7
    ISSN: 1573-1561
    Keywords: Schistocerca gregaria ; oviposition ; pheromone ; locust ; 6-octen-2-one ; 3,5-octadien-2-one
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Oviposition responses of gregarious adult gravid females of the desert locust Schistocerca gregaria to sand previously used for oviposition by gregarious females (contaminated sand, with eggs and froth removed) and to sterilized sand (noncontaminated sand) were compared in bioassays. Gregarious females preferentially oviposited into contaminated sand. The number of egg pods laid by the females was found to correlate with the frequency of use of the contaminated sand for oviposition. Charcoal-trapped volatiles from the contaminated sand also elicited similar responses from gregarious females. Gas chromatography–electroantennographic detection (GC-EAD) analysis of the trapped volatiles revealed the presence of three electrophysiologically active compounds that were identified by GC-MS as (Z)-6-octen-2-one, (E,E)-3,5-octadien-2-one and its geometric isomer (E,Z)-3,5-octadien-2-one. The relative amounts of the three EAG-active compounds in the volatiles increased with consecutive oviposition by the gregarious females. These results indicate mediation of additional pheromonal components in the oviposition behavior of gregarious desert locust that are distinct from those that were previously identified in the froth volatiles.
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  • 8
    ISSN: 1573-1561
    Keywords: Schistocerca gregaria ; Locusta migratoria migratorioides ; locust ; aggregation ; pheromone ; aliphatic acids ; aldehydes ; alcohols ; benzene derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Gregarious nymphs of Schistocerca gregaria and Locusta migratoria migratorioides are often seen to march together in common bands in the field. In the present study, the intraspecific aggregation responses of nymphal and older stages of the two insects were compared with their interspecific responses. Unlike S. gregaria, L. m. migratorioides shows a lesser pattern of stage and sex differentiation in its aggregation pheromone biology. Thus, although fifth-instar nymphs did not respond significantly to the adult pheromone, adults responded significantly to the nymph pheromone. No cross-stage aggregative responses occur in S. gregaria. In the adults of S. gregaria, production of the pheromone is male-specific; in L. m. migratorioides both sexes induced a significant level of aggregation from conspecifics. Aggregation assays between corresponding stages of the two species showed stronger interaction between the nymphal stages than between the adults and account for the frequent occurrence of mixed hopper bands in the field. GC-EAD studies of volatiles of nymphal and adult stages by using antennal preparations from both species also showed significant interspecies reactivities. GC-MS analyses showed that of S. gregaria nymphal pheromone components (C6 and C8 to C10 straight-chained aldehydes and acids and the fecal phenols, guaiacol and phenol), the acids and phenols constitute the common components of nymphal stages. Phenylacetonitrile, the major component of S. gregaria adult aggregation pheromone, is present in L. m. migratorioides nymphal volatiles, albeit at a lower level. Unlike S. gregaria adult pheromone blend, which is made up wholly of benzene derivatives, the volatile emissions of L. m. migratorioides adults is dominated by aliphatic aldehydes and alcohols. The possible role of cross-aggregation effects in mutually facilitating phase transformation of the two species is discussed.
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  • 9
    ISSN: 1573-1561
    Keywords: Airborne volatiles ; bioassay ; aggregation pheromones ; gregarious locusts ; olfactometer ; semiochemicals ; Orthoptera ; Acrididae ; Schistocerca gregaria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The response of nymphal and adult gregarious phase desert locust,Schistocerca gregaria, to a choice of two columns of air, one permeated with airborne volatiles emanating from nymphs or adults and the other untreated, was investigated in a single-chamber bioassay arena. The nymphs, whether released individually or in groups, preferred to be within the precinct of the air column treated with airborne volatiles of the nymphs but were indifferent to volatiles of the adults. Conversely, older adults responded only to their own volatiles but not to those of the nymphs or young adults. The young adults were responsive only to volatiles of the older adults. Charcoal-trapped volatiles from the nymphs and the adults reproduced the effect of living locusts. These results indicate that there are two different aggregation pheromones inS. gregaria: a juvenile pheromone produced by nymphs and an adult pheromone specific to adults.
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  • 10
    Publication Date: 2023-01-24
    Description: Bioassay data was collected using a bench top cage arena made of two Perspex cages (each 65 × 65 × 75 cm) connected through a rectangular Perspex tube of 65 cm at the top with 5 cm of both ends inserted into each cage. The tube had a square opening (entrance) of 5 × 5 cm fitted with a lid with both ends fitted with fine netting. The rectangular tube was demarcated into three zones; treatment, control and no choice. Fifty *Trioza erytreae* of same sex were introduced into the entrance and the number of insects were counted in each zone after one hour. Four replicates were done for each treatment set. The treatments were; Experiments 1; 1. Lemongrass vs air 2. Garlic vs air 3. Guava vs air Experiments 2; 4. Lemongrass vs rough lemon 5. Garlic vs rough lemon 6. Guava vs rough lemon Experiments 3; 7. Lemongrass+rough lemon vs rough lemon 8. Garlic+rough lemon vs rough lemon 9. Guava + rough lemon vs rough lemon. Insects counted in no zone were not included in the analysis.
    Keywords: Allium sativum; CA; Cage; Citrus; Citrus greening disease; Cymbopogon citratus; Event label; Experiment; Experimental treatment; Number of individuals; Psidium guajava; Repellence_Experiment-0; Repellence_Experiment-1; Repellence_Experiment-2; Repellence_Experiment-3; Repellent; Replicate; Sex
    Type: Dataset
    Format: text/tab-separated-values, 1008 data points
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