Oviposition Stimulants Research Articles

Structure-activity relationships for analogs of (+)-(E)-endo-?-bergamoten-12-oic acid, an oviposition stimulant ofHelicoverpa zea (Boddie)

Β-Bergamotenoic acid, a compound previously shown to stimulate oviposition inH. zea, was converted into a set of bicyclic analogs and tested with a set of acyclic side chain analogs to ascertain the molecular structure that maximizes insect behavioral response. While changes in the bicyclic ring elicited no variation in response, alteration in the side chain structure ofΒ-bergamotenoic acid resulted in significant changes in moth preference. Free rotation about the C-C bond proximal to the carboxylic acid group appears to be an important structural factor, since saturation of the side chain double bond significantly increased activity. The carboxylic acid group seems to be required for strong oviposition stimulation, since analogs lacking the carboxylic acid group exhibited no significant oviposition activity. Oviposition preference ofH. zea was also influenced by the length of the hydrocarbon chain to which the carboxylic acid is attached. While hexanoic acid was found inactive, the ovipositional preference for the heptanoic and octanoic acids was greatest for the one 8-carbon tested. This and other work suggest that carboxylic acids of specific chain lengths influence the oviposition behavior of bothHelicoverpa andHeliothis species and may be associated with host-plant selection. The potential use of this information in designing integrated pest management strategies for control ofH. zea is discussed.

Oviposition and tarsal chemoreceptors of the cabbage root fly are stimulated by glucosinolates and host plant extracts

AbstractThe role of glucosinolates in the oviposition behaviour of the cabbage root fly, Delia radicum (L.) (Diptera, Anthomyiidae) was investigated using egg counts and electrophysiological recordings from tarsal contact chemoreceptors. The glucosinolates present both inside and on the surface of cauliflower leaves were determined. The total amounts obtained with the two methods differed by a factor of 100. The extract of the leaf surface contained about 60 μg per g leaf extracted (gle), the total leaf extract 7.5 mg per gle. The glucosinolate patterns of the two extracts were qualitatively similar, but the ratios of the content of individual glucosinolates showed considerable differences.The D sensilla on segment 3 and 4 of the tarsus of D. radicum females were shown to contain a sensitive receptor cell for glucosinolates. In contrast, the receptor cells of the D sensilla of the other segments did not respond in a dose dependent way to these compounds. The glucosinolate receptors were found to be especially sensitive to glucobrassicin, gluconasturtiin and glucobrassicanapin with thresholds of about 10 −8M to 10 −9M. Large differences (up to two orders of magnitude) were observed among the different glucosinolates.A significant correlation was found between the behavioural discrimination index and the electrophysiological results. But no obvious correlation existed between the chemical nature of the glucosinolate side chain (e.g. indole, aromatic and aliphatic groups), and their stimulatory activity. However, a significant correlation was found between the overall length of the side chain and the biological activity.Although the flies discriminated clearly between model leaves with and without glucosinolates, a clear dose response curve was only obtained for the indole glucosinolate glucobrassicin. Since the most stimulatory fraction of the surface extract contained no glucosinolates, it was concluded that other compounds, in addition to glucosinolates, do play an important role for the stimulation of oviposition.

An inhibitory mechanism over oviposition in the tobacco cutworm, Spodoptera litura by juvenile hormone analogue pyriproxyfen

The effects of a juvenile hormone analogue, pyriproxyfen, on the reproduction of tobacco cutworm, Spodoptera litura, were examined. Topical application of 0.3 ng to day-0 female pupae reduced the number of eggs oviposited. Ovarian development and egg maturation in pyriproxyfen-treated moths were normal in most females. The reduction in eggs oviposited was due to the lack of an oviposition stimulating factor which was present in female haemolymph but not in male haemolymph. A lower activity of the factor was present in virgin females and pyriproxyfen-treated females. Precipitation with ammonium sulphate, heat treatment, dialysis and protease treatment showed that the factor is a protein and its molecular weight is more than 14 kDa.

Stimulation of Oviposition and Heterosis in Interstrain Crosses of European Corn Borer (Lepidoptera: Pyralidae)

Hybrid matings of two Ostrinia nubilalis (Hübner) (Lepidoptera: Pyralidae) colonies (N and O), established in the laboratory a year apart, demonstrated positive heterosis in the F1 generation as indicated by increases in pupal weight (6%), number of egg masses per female (65%) and number of eggs per female (77%) as compared to intra-colony crosses in mass matings. In contrast, pupation date, an indicator of development time, was intermediate in the hybrids relative to the parental colonies. There was also a 37% increase in the numbers of eggs/female and a 45% increase in egg masses/female in the hybrid parental cross. We investigated this stimulation of oviposition in single female, reciprocal crosses. Oviposition stimulation was directional with the cross of N colony males x O colony females exhibiting significantly higher numbers of total eggs/female and egg masses/female on a daily basis. Colony O females in this cross laid more large egg masses than females in other crosses. Data from individual female crosses demonstrated that egg production in hybrid mass mating experiments was consistent with random mating of males and females from both colonies.

Evidence for the accessory glands as the site of production of the oviposition attractant and/or stimulant ofLutzomyia longipalpis (Diptera: Psychodidae)

The phlebotomine sandflyLutzomyia longipalpis Lutz and Neiva, the vector of visceral leishmaniasis in South America, has recently been shown to produce an oviposition semiochemical. In the present study it was found that a nonpolar extract of eggs was attractive and/or stimulatory to ovipositing females. A Chromatographic investigation indicated the presence of similar compounds in accessory glands and egg extracts. Extract of accessory gland was also found to elicit a positive oviposition response. It is concluded that the pheromone is produced in the accessory glands and is secreted onto the eggs during oviposition.

The role of honeydew as an ovipositional stimulant for two species of syrphids

AbstractThe influence of honeydew contamination on egg laying by the syrphids Episyrphus balteatus (Deg.) and Platycheirus albimanus (F.) on ears of wheat was investigated in a large laboratory flight cage. Artificially‐applied honeydew elicited oviposition by E. balteatus but not by Platycheirus albimanus. Episyrphus balteatus females landed more frequently on ears contaminated with honeydew than on clean ears, suggesting a response to honeydew volatiles. Honeydew from the rose‐grain aphid Metopolophium dirhodum and from the pea aphid Acyrthosiphon pisum stimulated E. balteatus to lay eggs, whereas honeydew from the nettle aphid Microlophium carnosum did not. The number of eggs laid by E. balteatus increased with increasing honeydew concentration. At low honeydew concentrations the presence of aphids increased oviposition by E. balteatus, but aphid presence had little effect on the number of eggs laid at high honeydew concentrations.

Leaf surface compound fromBrassica oleracea (Cruciferae) induces oviposition byPieris brassicae (Lepidoptera: Pieridae)

Chemicals present on the surface of cabbage (Brassica oleracea L.) leaves were extracted by dipping these leaves for 3 s in dichloromethane followed by a 3 s dip in methanol. When offered in dual choice bioassays using green paper cards as a substrate, the methanol extract stimulated oviposition activity byPieris brassicae L. (Lepidoptera: Pieridae) females. The oviposition stimulant was isolated using medium pressure liquid chromatography, reversed-phase HPLC, ion-pair HPLC and ion exchange chromatography. Using1H-NMR spectroscopy, the stimulant could be identified as glucobrassicin (3-indolyl-methyl-glucosinolate). When pure glucobrassicin was offered at a dose identical to that in the crude methanol extract, butterflies did not discriminate between these two substrates in a dual choice test. It is argued that a high sensitivity for indole glucosinolates as host recognition factors may confer an adaptive value for these specialist crucifer feeders. The nutritional significance of their precursor tryptophan and the non-volatile nature of the aglycones formed upon enzymic hydrolysis in damaged tissues are proposed as properties of indole glucosinolates that contribute to this possible adaptive advantage.

Oviposition attractants and stimulants for the sandfly Lutzomyia longipalpis (Diptera: Psychodidae).

Oviposition preferences of Lutzomyia longipalpis Lutz & Neiva for surfaces containing frass (colony remains), larval rearing medium, and rabbit feces were investigated in the laboratory. In oviposition choice chambers, significantly more eggs were laid on sites containing frass, larval rearing medium, or rabbit feces than on untreated control sites. Experiments using unwashed and washed materials indicated, for the first time, the presence of chemical oviposition attractants or stimulants or both in larval medium (consisting of equal weight proportions of rabbit feces, potting compost, sand, and Daphnia). In an olfactometer, aroma from rabbit feces strongly attracted ovipositing females, and significantly higher numbers of eggs were laid in the olfactometer test chamber containing the rabbit feces than in the untreated control chamber. In comparisons of oviposition responses to hexane and distilled water extracts of rabbit feces, only the water extract was attractive. Similarly, the distilled water extract of rabbit feces proved to be an oviposition stimulant. Females kept individually with filter papers impregnated with the extract of feces oviposited earlier and survived longer than females kept with untreated papers.

Evaluation of Oviposition Stimulants for Mass Production of Melon Fly, Oriental Fruit Fly, and Mediterranean Fruit Fly (Diptera: Tephritidae)

Responses of Melon fly, Dacus cucurbitae Coquillett, oriental fruit fly, Dacus dorsalis Hendel, and Mediterranean fruit fly, Ceratitis capitata (Wiedemann), to artificial oviposition bottles treated with various liquids derived from host juices or extracts and water was tested in a choice test device. Harvest of D. cucurbitae eggs was 89.4% higher from oviposition bottles that contained the juice of pumpkin, Cucurbita maxima Duchesne, than from bottles with the juice of tomato, Lycopersicon esculentum Miller, the standard oviposition stimulant. Harvest of D. dorsalis eggs was 55.2% higher from oviposition bottles that contained juice of orange, Citrus sinensis (L.) Osbeck, than from bottles with juice of guava, Psidium guajava L., the standard oviposition stimulant. Harvest of C. capitata eggs from oviposition bottles that contained an extract of coffee, Coffea arabica L., was equal to those with the standard oviposition stimulant (water). Results indicate that host fruit juices with minimal commercial processing and without additives were the best oviposition stimulants. Findings are discussed in the context of oviposition stimulant evaluation procedures and mass production of tephritid fruit flies.

Pre-and Postharvest Changes in Sweetpotato Root Surface Chemicals Modulating Insect Resistance

Levels of major root surface components for two sweetpotato [Ipomoea batatas (L.) Lam.] cultivars that differ in susceptibility to the sweetpotato weevil [Cylas formicarius elegantulus (Summers)] were determined. Analyses were made 30 days before harvest, at harvest, after curing, and after 2 months of storage during two seasons. Significant variation in the amounts of individual components, especially boehmeryl acetate, which is known to be an ovipositional stimulant for the weevil, was found before and after harvest, with season, and between cultivars. These results suggest that variation in field susceptibility of cultivars displaying moderate levels of resistance may be due in part to seasonal variation in the level of ovipositional stimulants.

Volatile compounds in the larval frass ofDendroctonus valens andDendroctonus micans (Coleoptera: Scolytidae) in relation to oviposition by the predator,Rhizophagus grandis (Coleoptera: Rhizophagidae)

During a laboratory study evaluatingRhizophagus grandis (a specific native predator of the Eurasian bark beetle,Dendroctonus micans), as a potential biocontrol agent against the North American bark beetle,Dendroctonus valens, it was found that feeding larvae and laboratory-produced frass of the potential prey elicited very high oviposition responses in the predator. Comparative chemical analysis of this laboratory-produced larval frass revealed that one major volatile compound, (-)-fenchone, is associated with the larvae of bothDendroctonus species.D. micans also generated pinocamphone while oxygenated monoterpenes in the frass ofD. valens were camphor,cis-4-thujanol, fenchol, terpinen-4-ol, myrtenal, pinocarvone, borneol, verbenone, piperitone, campholenaldehyde,trans-myrtanol,cis-myrtanol,p-cymen-8-ol and 5-oxo-camphor. This range of prey-produced compounds with a possible biological effect onR. grandis was narrowed down subsequent to comparative analysis of field-collected larval frass. (-)-Fenchone, pinocamphone, camphor, terpinen-4-ol, borneol, fenchol, and verbenone were found to be common to both prey species. A mixture of these seven components was tested in a bioassay, where it elicited as much oviposition as did larval frass ofD. micans. The oviposition stimulants forR. grandis are thus clearly among the mixture's constituents.

Evaluation of Peach Cultivars as Peachtree Borer (Lepidoptera: Sesiidae) Hosts

Eleven peach cultivars were evaluated at Thorsby, Ala., and Byron, Ga., for bark prunasin content, bark thickness, peachtree borer larvae entrance sites, and peachtree borer adult emergence. Significant differences in larval weight occurred after 21 d of feeding on four different peach cultivars but were not evident after 42, 64, or 88 d. Prunasin content and bark thickness exhibited considerable variation with time, location, and cultivar. A significant positive correlation was found between prunasin content and emergence in 1 of 3 yr. In that year, larval entrance sites were positively correlated with emergence. This phenomenon was attributed to the presence of an ovipositional stimulant on trees that had previously supported the successful development of peachtree borers rather than an oviposition preference for trees with high prunasin content. A statistical correlation between peachtree borer emergence and bark thickness was not shown. However, the cultivar from which the greatest emergence occurred also had the greatest bark thickness. Results indicated that differences in host suitability exist among cultivars, but that host suitability may vary with environmental conditions.

Oviposition Stimulants for the Lesser Mulberry Pyralid,Glyphodes pyloalis(Walker), in Mulberry Leaves; Rediscovery of Phytoalexin Components as Insect Kairomones

Oviposition Stimulants for the Lesser Mulberry Pyralid,<i>Glyphodes pyloalis</i>(W<scp>alker</scp>), in Mulberry Leaves; Rediscovery of Phytoalexin Components as Insect Kairomones

A comparison between the amino acid composition of an egg parasitoid wasp and some of its hosts

AbstractAmino acid compositions of the eggs of five lepidopteran hosts for Trichogramma minutum were compared with each other and with a non‐host species, Rhodnius prolixus, in which T. minutum oviposits but does not develop. Host eggs are quite homogeneous, particularly when compared according to groupings of potentially interconvertible amino acids. Combined mole percent values for glycine, serine and alanine were higher in hosts (27.5–29.2 mole%) than in R. prolixus eggs (21.5 mole%), in bovine serum albumin (14.9%), which has been used as a protein source in artificial diets for T. minutum, or in many of the mixtures used in published diets for this species. Since these three amino acids make up 26.3 mole% of the adult amino acid content of T. minutum, their deficiency in diets could require metabolic compensation detrimental to development.Adult T. minutum arising from eggs of Manduca sexta, Choristoneura fumiferana, and Sitotroga cerealella are similar in amino acid composition to each other and, in general, to their hosts. Variability appears greater in hosts than in adult wasp composition, suggesting some interconversion of host amino acids to accommodate inflexible nutritional requirements of T. minutum.In the three host species tested, free amino acids constituted 15.8–19.3% by weight of the amino acid in egg contents. In M. sexta eggs, glycine, serine and alanine together make up 28.4% by weight of the total free amino acid, a much higher proportion than in many published diets. The four free amino acids (isoleucine, leucine, phenylalanine and histidine) reported to be oviposition stimulants in experiments on encapsulated diets are present in sufficient concentrations to induce oviposition in the host species tested and in R. prolixus.S. cerealella egg contents having approximately 1.8 μg amino acid, yield one or rarely two adult T. minutum (1 μg amino acid/insect). In contrast, M. sexta eggs with 94 μg amino acid each yield an average of 10–12 adults (8.2 μg amino acid/insect). This suggests that small hosts are allocated few eggs which can only develop into small adults because of nutrient supply (parasitoid size in metabolically restricted), whereas much larger hosts are allocated proportionately fewer eggs than the former resulting in larger, and presumably more viable and fecund, adults (parasitoid size is established behaviourally).

A Rapid Method for Screening Sweetpotato Genotypes for Oviposition Stimulants to the Sweetpotato Weevil

Methodology was developed for the rapid quantitative and qualitative screening of sweetpotato [Ipomoea batatas (L.) Lam.] germplasm for the concentration of the major sweetpotato weevil oviposition stimulant, boehmeryl acetate, and its alcohol, boehmerol. The major surface components were rapidly quantified, using a minimum of plant material. Boehmeryl acetate, present in methylene chloride root extracts, did not degrade when held under normal laboratory conditions for 45 days. Boehmeryl acetate and boehmerol were found only in the outer 1 to 1.2 mm of periderm and the distribution of the compounds appeared to be relatively uniform over the surface of the root.

Oviposition stimulants for the lesser mulberry pyralid, Glyphodes pyloalis (Walker), in mulberry leaves;rediscovery of phytoalexin components as insect kairomones.

The oviposition simulant for the lesser mulberry pyralid, Glyphodes pyloalis Walker, was isolated from an acetone extract of mulberry (Morus alba L.) leaves, and its structure was identified as 2-(3′,5′-dihydroxy-4′-prenylphenyl)-6-hydroxybenzofuran, viz. moracin C (1), a known phytoalexin from fungus-infected mulberry shoot. Moracin N (2) and ω-hydroxy moracin N (3) were also identified in the extract, but no ovipositional activity was demonstrated in these compounds. Synthetic moracin M, 2-(3′,5′-dihydroxyphenyl)-6-hydroxybenzofuran (4), as the basic skeleton of moracins, indicated weak activity as an oviposition stimulant. The increase in susceptibility of already-infested mulberry leaf is discussed in relation to the production of phytoalexins. All these compounds except co-hydroxy moracin N (3) are known as phytoalexins in the mulberry tree.

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.

EFFECTS OF SUB-LETHAL EXPOSURES TO MALATHION OR CHLORPYRIFOS-METHYL ON OFFSPRING PRODUCTION BY SOME STORED-PRODUCT BEETLES

AbstractExposure of adult rusty grain beetles, Cryptolestes ferrugineus (Stephens), saw-toothed grain beetles, Oryzaephilus surinamensis (L.), and red flour beetles, Tribolium castaneum (Herbst), to filter papers treated with the organophosphorus insecticides malathion or chlorpyrifos-methyl often affected offspring production in survivors. Groups of five male and five female survivors were placed on ground wheat at 30°C and C. ferrugineus and O. surinamensis adults produced fewer offspring with prolonged exposure to chlorpyrifos-methyl; malathion had no effect. Tribolium castaneum adults produced significantly more offspring with increasing exposure to both malathion and chlorpyrifos-methyl indicating stimulation of oviposition or a selection for increased fitness in survivors.

Effect of a Pentacyclic Triterpene from Sweet Potato Storage Roots on Oviposition by the Sweetpotato Weevil (Coleoptera: Curculionidae)

Apentacyclic triterpenoid, boehmeryl acetate, was identified as the dominant peak in gas chromatographic profiles of the periderm of susceptible sweet potato cultivars. Boehmeryl acetate, present in the methylene chloride-hexane (1:3) fraction of methylene chloride surface extracts, induced significantly ( P < 0.05) higher oviposition by female sweetpotato weevils on sweet potato cores in laboratory bioassays. Dose-response studies showed significant linear and quadratic log dose effects, with peak oviposition stimulating activity for this compound at about 0.01 potato equivalents (0.04 μ g/core). Results indicate that boehmeryl acetate is an oviposition stimulant of the sweetpotato weevil, Cylas formicarlus elegantulus (Summers).

Chemical Ecology of Dacinae Fruit Flies (Diptera: Tephritidae)

There are more than 700 described species of Dacinae fruit flies, whose immature stages develop in many species of fleshy fruits found in tropical and subtropical rain forests. Most of these species are monophagous or stenophagous, but a few species are polyphagous. The Dacinae have a complex chemical ecology, responding to sex pheromones produced by females, aphrodisiac pheromones produced by males, plant kairomones that function as male lures, and plant-produced oviposition stimulants. This review focuses on current understanding of Dacinae chemical ecology as it relates to evolution, host selection, reproduction, adult behavior, and control of these fruit flies.