Short-range Attractant Research Articles

Short-range attraction and oviposition stimulant of a biocontrol agent, Galerucella placida Baly (Coleoptera: Chrysomelidae) toward weed leaf surface waxes.

Two Polygonaceae weeds, Rumex dentatus L. and Polygonum glabrum Willd. are abundant in wheat- and rice-fields, respectively, in India. Galerucella placida Baly (Coleoptera: Chrysomelidae) is a biocontrol agent of these two weeds. The importance of long-chain alkanes and free fatty acids present in leaf surface waxes of these weeds was assessed as short-range attractant and ovipositional stimulant in G. placida females. Extraction, TLC, GC-MS and GC-FID analyses demonstrated 19 n-alkanes from n-C14 to n-C35 and 14 free fatty acids from C12:0 to C22:0 in leaf surface waxes. Hentriacontane was predominant among alkanes in both weeds, while oleic acid and docosanoic acid were predominant among free fatty acids in R. dentatus and P. glabrum, respectively. Females of G. placida were attracted toward one leaf equivalent surface wax of both weeds against the control solvent (petroleum ether) in a short Y-tube olfactometer bioassay. But, the insect could not differentiate between one leaf equivalent surface wax of R. dentatus and P. glabrum, indicating that both weed leaves were equally attractive in females. A synthetic blend of either 2.44, 35.57 and 23.58 μg ml-1 of octadecane, heptacosane and nonacosane, respectively, resembling the amounts present in one leaf equivalent surface wax of R. dentatus or 4.08, 19.54 and 23.58 μg ml-1 of octadecane, palmitoleic acid and docosanoic acid, respectively, resembling the amounts present in one leaf equivalent surface wax of P. glabrum acted as short-range attractant and ovipositional stimulant in G. placida. These results could be a basis for host plant specificity of the biocontrol agent.

A Keller-Segel model for C elegans L1 aggregation.

We describe a mathematical model for the aggregation of starved first-stage C elegans larvae (L1s). We propose that starved L1s produce and respond chemotactically to two labile diffusible chemical signals, a short-range attractant and a longer range repellent. This model takes the mathematical form of three coupled partial differential equations, one that describes the movement of the worms and one for each of the chemical signals. Numerical solution of these equations produced a pattern of aggregates that resembled that of worm aggregates observed in experiments. We also describe the identification of a sensory receptor gene, srh–2, whose expression is induced under conditions that promote L1 aggregation. Worms whose srh–2 gene has been knocked out form irregularly shaped aggregates. Our model suggests this phenotype may be explained by the mutant worms slowing their movement more quickly than the wild type.

A Multimodal Attract-and-Kill Device for the Asian Citrus Psyllid Diaphorina citri (Hemiptera: Liviidae).

Simple SummaryControl of Asian citrus psyllid (Diaphorina citri), a vector of Candidatus liberibacter asiaticus (CLas), contributes to management of citrus greening disease (huanglongbing). We developed two prototypes of a multimodal attract-and-kill (AK) device with specific elements of color, attractant, phagostimulant, ultraviolet (UV) reflectant, and toxicant. Key sensory stimuli comprising the AK ingredients were identified in our current and previous research studies and incorporated into a yellow, slow-release wax matrix (SPLAT). This formulation was applied directly to the surface of yellow cylinders, or to corrugated plastic cards housed within perforated cylinders. Psyllids landing on the devices attempted to feed from the wax matrix, became intoxicated, died, and fell from device surfaces. Our laboratory and field experiments showed that AK devices attracted and killed significantly more adult D. citri than ordinary yellow sticky cards and remained fully active over a period of 12 weeks. Effective use of attract-and-kill for management of D. citri could reduce need for broad-spectrum insecticide sprays and encourage biological control as part of an integrated approach to huanglongbing (HLB) management in citrus.Phytophagous insects, including Asian citrus psyllids (Diaphorina citri Kuwayama), use multiple sensory modalities (vision, olfaction, and gustation,) to locate and accept host plants. We explored incorporation of several sensory cues into a multi-modal attract-and-kill device (AK device) using a three-dimensional shape to increase visibility, as well as elements of color, attractant, phagostimulant, UV reflectant, and toxicant. Attraction of adult D. citri to the device was mediated by a combination of a highly reflective yellow cylinder, a UV reflectant compound (magnesium oxide), and an odorant blend as a short-range attractant. The device surface was coated with a slow-release wax matrix (SPLAT™) augmented with a phagostimulant consisting of a 3-component blend (formic acid, acetic acid, and para-cymene) and an insecticide (β-cyfluthrin). Psyllids landing on the device attempted to feed from the wax matrix, became intoxicated, died, and fell from the device. The device remained fully active over a period of 12 weeks partly because dead psyllids or nontargets did not adhere to the surface as occurs on adhesive yellow sticky cards, the industry standard. Laboratory and field assays showed that the device attracted and killed significantly more adult D. citri than ordinary yellow sticky cards. This device or a future iteration based on the design elements of this device is expected to contribute to sustainable and environmentally appropriate management of D. citri by exploiting the psyllid’s innate behavioral responses to visual, olfactory, and gustatory stimuli.

Controlled-Release Dispenser and Dry Trap Developments for Drosophila suzukii Detection

The spotted wing drosophila (SWD), Drosophila suzukii, is an exotic vinegar fly originating from South-East Asia and has invaded many American and European countries. This devastating pest has caused severe damage on soft-skinned fruit crops, which has resulted in large economic losses. Although many D. suzukii detection devices have been developed and used by growers/farmers in orchards, most of them did not meet their expectation. More simple, convenient, and efficient detection tools are still urgently needed so that growers/farmers can make timely management decision. In our previous study a quinary blend, containing acetoin, as a long-range, and ethyl octanoate, as a short-range attractant for SWD, had been identified. In this study, a controlled-release polyethylene dispenser containing five identified attractants: acetoin, ethyl octanoate, ethyl acetate, penethyl alcohol, and acetic acid, was tested in laboratory conditions for release rates, as well as in a blueberry field and an adjacent wooded area for trapping activity. Release of the most D. suzukii attractants from the polyethylene dispenser was constant. In the laboratory, release rates of ethyl acetate (0.3 g/day over 14 days), phenethyl alcohol (0.0054 g/day over 36 days), and acetic acid (0.13 g/day over 36 days) followed zero order kinetics. Acetoin and ethyl octanoate were blended together and had a varied release rate. In the field, dry and liquid traps baited with the optimized controlled-release dispenser were evaluated and compared with liquid traps baited with apple cider vinegar (ACV). During blueberry harvest season in 2018, the liquid traps containing drowning solution baited with the optimized controlled-release dispenser caught both male and female D. suzukii two weeks earlier and had significantly higher selectivity than that of ACV traps in the field. Additionally, in 2019 field tests, dry traps baited with the controlled-release dispenser demonstrated earlier detection compared to the ACV traps. Due to the simplicity of the dry trap design and easy processing, it has great potential to be an efficient and convenient D. suzukii detection tool for growers/farmers.

Leaf waxes from Lathyrus sativus: short-range attractant and stimulant for nymph laying in a viviparous insect

Lathyrus sativus L. (Fabaceae) is an important pulse crop of Asia, Europe, and Africa. Infestation by the aphid, Aphis craccivora Koch (Hemiptera: Aphididae) causes stunted growth of plants and reduces seed production. Females lay nymphs on the leaves and flowers of L. sativus. Hence, it is relevant to study the importance of leaf wax compounds (long-chain alkanes and free fatty acids) from two cultivars [BIO L 212 Ratan (BIO) and Nirmal B-1 (NIR)] of L. sativus as short-range attractant and stimulant for nymph laying in the aphid. The TLC, GC-MS and GC-FID analyses of n-hexane extracts from leaves of two cultivars revealed 18 n-alkanes from n-C15 to n-C36 and 14 free fatty acids from C12:0 to C22:0. Pentadecane was predominant among n-alkanes in both cultivars. Palmitoleic acid and pentadecanoic acid were predominant free fatty acids in leaf waxes of BIO and NIR, respectively. Females were attracted towards leaf waxes of both cultivars compared to the control solvent (n-hexane) in Y-tube olfactometer bioassays. A synthetic blend of either pentadecane, tridecanoic acid, and linoleic acid at similar amounts present in one leaf equivalent wax of BIO, or pentadecane, docosane, pentacosane, heptacosane, tritriacontane, and linoleic acid at similar amounts present in one leaf equivalent wax of NIR acted as short-range attractant and stimulated females to lay nymphs. But, the latter blend was more attractive and stimulated females to lay more nymphs than the former blend, and hence, this latter blend could be employed in the development of baited traps in pest management strategies.

The role of Lathyrus sativus flower surface wax in short-range attraction and stimulant for nymph laying by an adult viviparous aphid.

Aphis craccivora Koch (Hemiptera: Aphididae) is an important pest of Lathyrus sativus L. plants, and causes retarded plant growth and loss of seed production. The insect sucks cell sap from flowers and lays nymphs on flowers. Hence, an attempt has been made to observe whether flower surface wax compounds (alkanes and free fatty acids) from two cultivars (BIO L 212 Ratan and Nirmal B-1) of L. sativus could act as short-range attractant and stimulant for nymph laying by adult viviparous females. The n-hexane extracts of flower surface waxes were analyzed by TLC, GC-MS and GC-FID analyses. Twenty one and 22 n-alkanes between n-C12 and n-C36 were detected in BIO L 212 Ratan and Nirmal B-1, respectively; whereas 12 free fatty acids between C12:0 and C22:0 were identified in both cultivars. Pentadecane and tridecanoic acid were predominant n-alkane and free fatty acid, respectively. One flower equivalent surface wax of both cultivars served as short-range attractant and stimulant for nymph laying through Y-tube choice experiments and I-tube viviparity assays, respectively, by adult viviparous females. A synthetic blend of nonacosane, tridecanoic acid and linoleic acid, and a synthetic blend of tetradecane, pentadecane, nonacosane, tridecanoic acid and linoleic acid resembling in amounts as present in one flower equivalent surface wax of BIO L 212 Ratan and Nirmal B-1, respectively, served as short-range attractant and stimulant for nymph laying by adult viviparous females. This study suggests that both these blends could be used in lures in the development of baited traps in pest management programmes.

A beetle biocontrol agent of rice-field weeds recognizes its host plants by surface wax long-chain alkanes and free fatty acids

The importance of long-chain alkanes and free fatty acids present in leaf surface waxes of two Commelinaceae rice-field weeds, Commelina benghalensis L. and Murdannia nudiflora (L.) Brenan, was evaluated as short-range attractant and oviposition stimulant in the Lema praeusta (Fab.) (Coleoptera: Chrysomelidae). Surface waxes were extracted by dipping leaves in n-hexane for 1 min at 27 ± 1 °C. Thin-layer chromatography, gas chromatography–mass spectrometry, and gas chromatography–flame ionization detection analyses of n-hexane extracts revealed 20 n-alkanes from C14 to C36 and 13 free fatty acids from C12:0 to C22:0. Pentacosane and palmitoleic acid were predominant among n-alkanes and free fatty acids, respectively. Females showed attraction to one leaf equivalent surface wax of both weeds against the control solvent (petroleum ether) in Y-tube olfactometer bioassays. However, the insect could not discriminate between one leaf equivalent surface waxes of two weeds, suggesting that both weeds were equally attractive to females. Among all identified alkanes and fatty acids, females showed attraction towards individual docosane, tricosane, pentacosane and heptacosane, and tridecanoic acid, palmitoleic acid, linoleic acid, and arachidic acid, resembling in amounts as present in one leaf equivalent surface wax of C. benghalensis and M. nudiflora, respectively. A synthetic blend of either docosane, tricosane, pentacosane, and heptacosane, resembling in amounts as present in one leaf equivalent surface wax of C. benghalensis, or tridecanoic acid, palmitoleic acid, linoleic acid, and arachidic acid, resembling in amounts as present in one leaf equivalent surface wax of M. nudiflora, served as short-range attractant and oviposition stimulant in L. praeusta.

Behavioural responses of the parasitoid Aphytis melinus to volatiles organic compounds (VOCs) from Aonidiella aurantii on its host fruit Tahitian lime fruit Citrus latifolia

Aphytis melinus DeBach (Hymenoptera: Aphelinidae) is a parasitoid of Aonidiella aurantii (Maskell) (Hemiptera: Diaspididae). However, the cues used by A. melinus for host location have not been extensively investigated. Many studies have shown that mating parasitoids are strongly attracted by specific volatiles from infested plants. This paper investigated the response of A. melinus to volatiles from Tahitian lime fruit infested with A. aurantii through two-choice olfactometer bioassays. First, we identified the chemicals emitting from non-infested and A. aurantii-infested lime fruit via gas chromatography-mass spectrometry analyses and solid phase microextraction and identified 26 volatile organic compounds (VOCs). Eighteen of these were increased by A. aurantii infestation, and one was decreased, whereas five compounds were produced exclusively from infested fruit. Innate positive chemotaxis of mating A. melinus females toward lime fruit and their VOCs was then tested in olfactometer assays. Compared to the control without fruit, female A. melinus showed significantly greater attraction to healthy and A. aurantii-infested lime fruit, while there were no significant differences in the attraction of the parasitoid between healthy fruit or fruit infested with the second and third instar of A. aurantii. Among the two synthetic compounds tested, d-limonene and β-ocimene elicited a strong attraction for parasitoids at tested dosages (15 μl/ml), indicating an intrinsic response to this compound as a short-range attractant. Results from this study suggest that A. melinus parasitoids mainly rely on olfactory cues in host habitat location and that d-limonene and β-ocimene are the major attractants in infested fruit volatiles. Practically, field applications of this volatile may play a significant role in attracting more A. melinus to enhance the efficiency of biological control of A. aurantii in the future.

Innate and Learned Responses of the Tephritid ParasitoidPsyttalia concolor(Hymenoptera: Braconidae) to Olive Volatiles Induced byBactrocera oleae(Diptera: Tephritidae) Infestation

Parasitic wasps can learn cues that alter their behavioral responses and increase their fitness, such as those that improve host location efficiency. Psyttalia concolor (Szépligeti) (Hymenoptera: Braconidae) is a koinobiont endoparasitoid of 14 economically important tephritid species, including the olive fruit fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae). In this research, we investigated the nature of olfactory cues mediating this tritrophic interaction. First, we identified the chemical stimuli emanating from uninfested and B. oleae-infested olive fruits via solid phase microextraction and gas chromatography-mass spectrometry analyses and identified >70 volatile organic compounds (VOCs). Two of these were increased by B. oleae infestation, (E)-β-ocimene and 2-methyl-6-methylene-1,7-octadien-3-one, and four were decreased, α-pinene, β-pine ne, limonene, and β-elemene. Innate positive chemotaxis of mated P. concolor females toward these VOCs was then tested in olfactometer assays. Females were attracted only by (E)-β-ocimene, at both tested dosages, indicating an intrinsic response to this compound as a short-range attractant. Next, we tested whether mated P. concolor females could learn to respond to innately unattractive VOCs if they were first presented with a food reward. Two nonassociative controls were conducted, i.e., "odor only" and "reward only." Following training, females showed positive chemotaxis toward these VOCs in all tested combinations, with the exception of limonene, a VOC commonly produced by flowers. Control females showed no significant preferences, indicating that positive associative learning had occurred. These results clarify how learned cues can fine-tune innate responses to B. oleae-induced VOCs in this generalist parasitoid of tephritid flies.

Proteolysis and membrane capture of F-spondin generates combinatorial guidance cues from a single molecule

The formation of neuronal networks is governed by a limited number of guidance molecules, yet it is immensely complex. The complexity of guidance cues is augmented by posttranslational modification of guidance molecules and their receptors. We report here that cleavage of the floor plate guidance molecule F-spondin generates two functionally opposing fragments: a short-range repellent protein deposited in the membrane of floor plate cells and an adhesive protein that accumulates at the basement membrane. Their coordinated activity, acting respectively as a short-range repellant and a permissive short-range attractant, constricts commissural axons to the basement membrane beneath the floor plate cells. We further demonstrate that the repulsive activity of the inhibitory fragment of F-spondin requires its presentation by the lipoprotein receptor–related protein (LRP) receptors apolipoprotein E receptor 2, LRP2/megalin, and LRP4, which are expressed in the floor plate. Thus, proteolysis and membrane interaction coordinate combinatorial guidance signaling originating from a single guidance cue.

Arabidopsis hapless mutations define essential gametophytic functions.

In flowering plants, the egg develops within a haploid embryo sac (female gametophyte) that is encased within the pistil. The haploid pollen grain (male gametophyte) extends a pollen tube that carries two sperm cells within its cytoplasm to the embryo sac. This feat requires rapid, precisely guided, and highly polarized growth through, between, and on the surface of the cells of the stigma, style, and ovary. Pollen tube migration depends on a series of long-range signals from diploid female cells as well as a short-range attractant emitted by the embryo sac that guides the final stage of tube growth. We developed a genetic screen in Arabidopsis thaliana that tags mutant pollen with a cell-autonomous marker carried on an insertion element. We found 32 haploid-disrupting (hapless) mutations that define genes required for pollen grain development, pollen tube growth in the stigma and style, or pollen tube growth and guidance in the ovary. We also identified genomic DNA flanking the insertion element for eleven hap mutants and showed that hap1 disrupts AtMago, a gene whose ortholog is important for Drosophila cell polarity.

Kairomones Used by Trichogramma chilonis to Find Helicoverpa assulta Eggs

Chemically mediated interactions between an egg parasitoid, Trichogramma chilonis, and its host insect, Helicoverpa assulta, were studied in laboratory experiments. T. chilonis was attracted to the sex pheromone of H. assulta, and, among four components of its sex pheromone, (Z)-11-hexadecenyl acetate seemed to be most attractive. T. chilonis was also highly attracted to (E)-12-tetradecenyl acetate, a component of the sex pheromone of Ostrinia furnacalis, another host. H. assulta eggs were more parasitized by T. chilonis when the eggs were treated with male moth scale extract (MSE) of H. assulta. Parasitism was also affected by the age of the parasitoid, time of day, and MSE concentration. Silica gel chromatography and subsequent argentation chromatography for MSE fractionation indicated the activity was associated with the fraction of saturated hydrocarbons. A linear olfactometer experiment revealed that H. assulta eggs also contain a short-range attractant(s).

Aggregation pheromone of Pityogenes knechteli and semiochemical-based interactions with three other bark beetles

Gas chromatographic–electroantennographic detection and GC-mass spectrometric analyses of volatile extracts from male and female Pityogenes knechteli Swaine identified hexanol, (±)-ipsdienol, and (S)-(–)-ipsenol as male-produced candidate pheromone components. In a lodgepole pine, Pinus contorta var. latifolia Engelmann, forest in the southern interior of British Columbia, multiple-funnel traps baited with (±)-ipsdienol alone, (S)-(–)-ipsenol alone, or both caught 60%, 6%, and 23%, respectively, of all P. knechteli trapped; unbaited traps caught the remaining 11%. In another field trapping experiment, (S)-(+)-ipsdienol was as attractive as (±)-ipsdienol, and (R)-(–)-ipsdienol was behaviorally benign. (S)-(+)-Ipsdienol is thus concluded to be the principal aggregation pheromone component of P. knechteli. At low release rates, hexanol increased attraction of beetles to (±)-ipsdienol, or to (±)-ipsidienol plus (S)-(–)-ipsenol, but at high release rates hexanol decreased attraction, suggesting a role in preventing overpopulation in the host tree. On the basis of laboratory bioassays in which walking beetles were attracted to (S)-(–)-ipsenol, we hypothesize that (S)-(–)-ipsenol serves as a short-range attractant for P. knechteli. Three sympatric scolytids were also captured in field experiments as follows: the pine engraver, Ips pini (Say), to its pheromone (±)-ipsdienol; I. latidens LeConte to its pheromone (S)-(–)-ipsenol; and I. mexicanus (Hopkins), for which the pheromone is unknown, to (S)-(–)-ipsenol with (±)-ipsdienol. Although all four species attack lodgepole pine, we have never observed I. latidens or I. mexicanus attacking the same hosts at P. knechteli or I. pini. These results suggest that ipsenol and ipsdienol serve as synomones involved in promoting aggregation on the host tree, maintaining species-specific communication, and thus contributing to resource partitioning and reduced competition among the four species.

Host-Plant Selection by the Mexican Bean Beetle, Epilachna varivestis1

The Mexican bean beetle, Epilachna varivestis Mulsant, feeds selectively on certain species of Phaseolus to the exclusion of the remaining representatives of this and other genera of beans. In a study of the chemical factors underlying this selective feeding, the phagostimulant fraction in the seeds of P. vulgaris was isolated and identified as sucrose. Bioassay of 13 sugars and 15 amino acids showed that only sucrose and, to a lesser degree, its hexose components induced feeding by the beetle. The seeds as well as leaves of the nonresistant species of Phaseolus were found to have a higher concentration of sucrose, glucose, and fructose, thereby revealing the role these sugars play as arrestants in host-plant selection by the beetle. Bioassay of the volatile fraction from foliage of host-plants yielded positive olfactory responses from Mexican bean beetle larvae, and only indirect evidence of similar responses from the adults. These findings indicate the presence of a short-range attractant in the volatile constituents of hostplants. The influence of both attractants and arrestants in host-plant selection by insect pests is discussed, and the significance of quantitative differences in essential nutrients in host-plants is stressed. Phytogeographical factors relating to the 10 common species of Phaseolus also are discussed, emphasizing that in host-plant selection their role, if any, is only subordinate to stimulant chemicals in plants.