Field Bioassays Research Articles

Essential oils mediated antivirulence therapy against vibriosis in Penaeus vannamei

The emergence of new virulent Vibrio strains resistant to common antibiotics has caused significant economic losses to shrimp farming worldwide. It is mandatory to adopt new strategies to control shrimp farming related vibriosis. Essential oils (EOs) have several biological properties among of which the quorum sensing (QS) inhibitory activity is appealing for vibriosis control. In this work, we evaluated QS inhibitory activity of five EOs obtained from oregano (Organum vulgare), tea tree (Melaleuca alternifolia), lemongrass (Cymbopogon citratus), cinnamon (Cinnamomum verum) and thyme (Thymus vulgaris), at sublethal doses. EOs involvement in bioluminescence shutdown, biofilm formation and swarming motility was evaluated in four Vibrio strains of aquaculture interest including V. harveyi, V. campbellii, V. vulnificus, and V. parahaemolyticus. Oregano oil (EOOv) and tea tree oil (EOMa) were further tested in in vivo assays due to their significant effects (P < 0.05) on QS inhibition. EOOv was the most efficient one and exerted a comparable QS inhibitory effect to EOMa at a lower concentration in vivo (2.5 μg mL−1 of EOMa versus 1.0 μg mL−1 of EOOv). The lowest active doses of EOOv and EOMa that inhibited QS had no toxic effects on hemocytes and larvae of P. vannamei. A challenge test was performed in P. vannamei postlarvae (PL8) with V. campbellii, grown previously in the presence of EOOv or EOMa at sublethal active doses. Our results indicated that both EOs affected the virulence of V. campbellii and were able to significantly (P < 0.05) reduce shrimp mortality (EOOv in a 40% while EOMa in a 32%). A field bioassay was also carried in earthen ponds to test two different concentrations of EOOv and EOMa for feed supplementation (2.5 and 5.0 mg kg−1 respectively). EOOv increased significantly (P < 0.05) shrimp survival and yield at both doses, whereas EOMa increased shrimp survival and yield only at the highest dose. In conclusion, EOOv and EOMa constitute suitable alternatives to reduce vibrios virulence and to increase yield in shrimp culture systems.

Identification and field bioassays of the sex pheromone of Eurytoma maslovskii (Hymenoptera: Eurytomidae)

Long-range sex pheromones are generally considered to be a main cue for mate recognition in the order Hymenoptera. Although considerable attention has been given to the identification of semiochemicals in the superfamily Chalcidoidea, which comprises 19 families, no study has identified active components in a field bioassay. We herein report the sensitive and selective pheromone communication system of the Korean apricot wasp, Eurytoma maslovskii (Eurytomidae), whose larvae feed on Prunus mume seeds. Using gas chromatography coupled with electroantennographic detection (GC-EAD) and mass spectrometry (GC-MS), we detected 2,10-dimethyldodecyl propionate and 2,8-dimethyldecyl propionate in thoracic extracts of female E. maslovskii at a ratio of 8:2 as the active pheromone components. Field experiments showed that the attractive effect of the two compounds is highly enantioselective. Racemic 2,10-dimethyldodecyl propionate and 2,8-dimethyldecyl propionate were not attractive to E. maslovskii males. In bioassays with single enantiomers, the (2 S,10 R)-enantiomer was highly attractive to male wasps, and the (2 S,8 S)-enantiomer was also attractive, although to a lesser degree. No synergistic effect between (2 S,10 R)- and (2 S,8 S)-enantiomers was identified, and the (2 S,10 R)-enantiomer alone caught significantly more males than the natural pheromone extracts. The addition of other enantiomers to the (2 S,10 R)-isomer significantly decreased the attraction of conspecific males. In addition, a very low dose of synthetic pheromone attracted conspecific males, showing that both female signaling and male response traits may have evolved to contribute to species-specific sexual communication in this species.

Effect of Native Strains of Hirsutella citriformis1 on Diaphorina citri2 Adults under Field Conditions

Huanglongbing disease caused by the bacterium Candidatus Liberibacter is transmitted from infected to healthy plants by the Asian citrus psyllid, Diaphorina citri Kuwayama. Infectivity by conidia of five strains of Hirsutella citriformis Speare applied by contact was evaluated in field bioassays against D. citri adults. Bioassays were in three orchards of Persian lime (Citrus aurantiifolia (Christm. et Panz.) Swingle var. latifolia Yu. Tanaka) and one Mexican lemon (Citrus aurantiifolia Swingle) orchard at Chiapas, Campeche, Quintana Roo, and Colima states in Mexico. Treatments remained bagged on citrus trees in the field for 21 days after application. The five strains were pathogenic to the Asian citrus psyllid; CHE-CNRCB 339 and INIFAP-Hir-2 strains killed the most (74.1 and 68.3%, respectively). Most mycosis (71.1%) was by CHE-CNRCB 339. Preliminary results in the field confirmed the potential of H. citriformis to control Huanglongbing in Mexico.

Aphid-infested beans divert ant attendance from the rosy apple aphid in apple-bean intercropping

Ecological intensification of cropping systems aims at restoring multi-functionality while supporting current productivity levels. Intercropping is a form of ecological intensification involving ecological processes beneficial to farmers that do not take place in monocultures. Thus, it represents a practical approach to decrease the use of synthetic inputs such as insecticides in cultivated systems. Whereas insecticide reduction via intercropping-facilitated suppression of aphids is reported in literature, the majority of published studies focussed on herbaceous crops. Thus, the effect of intercropping on aphid populations of cultivated trees remains largely unaddressed. In this study we hypothesized that intercropping a specific companion plant within perennial crops would divert ant attendance from an aphid attacking the crop to another aphid feeding on the newly introduced plant, reducing aphid damage on the crop. We tested our hypothesis in the system of apple (Malus domestica Borkhausen), the rosy apple aphid (Dysaphis plantaginea Passerini) and the black garden ant (Lasius niger L.). Bean plants (Vicia faba) with the black bean aphid (Aphis fabae Scopoli) were intercropped within apple trees inoculated with D. plantaginea. We measured ant attendance, aphid development and survival as well as honeydew composition on both plant species through semi-field and field experiments. The majority of ants chose to attend A. fabae over D. plantaginea in the semi-field experiment with potted plants. In the orchard, a larger majority of scouts were scored on A. fabae over D. plantaginea. A higher number of D. plantaginea colonies remained active in the apple control, whilst they were almost eradicated by intercropping. Although chemical analyses of honeydew disclosed differences in the carbohydrate and amino acid profiles between aphid species, the difference in honeydew composition did not explain the preference for A. fabae. Ants did not discriminate between the two honeydew mimics both in laboratory and field bioassays. Our results showed the potential of intercropping apple trees with beans as a method to reduce ant attendance and thus colony survival. We propose that intercropping represents a bottom-up approach towards ecological intensification of perennial crops. Together with other ecosystem-based measures such as habitat management, intercropping should be considered when planning ecosystem redesign to increase biological control of pests.

Dung mimicry inTyphonium(Araceae): explaining floral trait and pollinator divergence in a widespread species complex and a rare sister species

AbstractThe process of pollinator-driven evolution is best studied at the level of populations and among closely related plant species. Araceae provide a plant model for investigating plant–pollinator interactions, but few studies have investigated intraspecific variation in their pollination systems. Typhonium brownii (Araceae) is distributed widely across 2000 km from tropical to temperate latitudes in Australia, yet the existence of intraspecific variation and ecotypes has not been investigated. Typhonium brownii from five regions, potentially representing distinct taxa, and populations of the sister species, T. eliosurum, were studied to explore pollinator and floral trait divergence. We characterize significant intraspecific floral trait variation in T. brownii, indicating the existence of a species complex, despite the taxa trapping similar Coleoptera (Staphylinidae, Scarabaeidae). Although all T. brownii showed similar temperature increases in the appendix, there were significant shifts in the timing and pattern of thermogenic and anthesis rhythms between regions (taxa), and all T. brownii taxa had distinct scent compositions, with T. sp. aff. brownii being the most dissimilar to other taxa. In contrast, T. eliosurum inflorescences almost exclusively trapped Diptera (Sphaeroceridae, Psychodidae), had modest temperature increases confined to the staminate zone and had a distinct scent profile which differed from all T. brownii taxa; this scent was confirmed in field bioassays to be important for pollinator attraction. Prevalent volatile organic compounds (VOCs) emitted by T. eliosurum and T. brownii taxa included the common dung constituents skatole, indole and p-cresol. Typhonium eliosurum and T. brownii taxa further differed significantly in morphology and trapping mechanisms, particularly the fly-pollinated T. eliosurum. It is possible that a subset of ubiquitous VOCs identified in T. eliosurum and T. brownii taxa attract local communities of dung-seeking flies and beetles, and that floral morphological features are more important for trapping different insect orders in these dung mimics.

Variations on a Theme: Two Structural Motifs Create Species-Specific Pheromone Channels for Multiple Species of South American Cerambycid Beetles.

We describe the identification, synthesis, and field-testing of aggregation-sex pheromones, or likely pheromone candidates, of seven species of South American cerambycid beetles in the subfamily Cerambycinae, of the tribes Eburiini and Neoibidionini. Analyses of extracts of volatiles released by adult males revealed that Eburodacrys dubitata White produce 11-methyltridecanal, whereas the males of Eburodacrys assimilis Gounelle, Eburodacrys flexuosa Gounelle, and Eburodacrys lenkoi Napp and Martins produce blends of this compound, along with its analog 10-methyldodecanal. In contrast, males of Compsibidion graphicum (Thomson) and Compsibidion sommeri (Thomson) produce blends of 10-methyldodecanal and its corresponding alcohol 10-methyldodecanol. The results from field bioassays with synthetic compounds showed that each species was specifically attracted to traps containing their reconstructed pheromone blend. However, E. assimilis was not trapped, possibly due to inhibition by non-natural enantiomers in the racemic test compounds. During the trials for the Compsibidion species, adults of another cerambycid species, Tetraopidion mucoriferum (Thomson), were captured in significant numbers in traps baited with 10-methyldodecanol, suggesting that this compound is a pheromone component for this species. This study demonstrates another case of conservation of pheromone structures within South American cerambycid species. It also highlights how blends of closely related structures, differing only in chain length or functional group, make the evolution of species-specific pheromone channels possible.

Host plants alter their volatiles to help a solitary egg parasitoid distinguish habitats with parasitized hosts from those without.

When attacked by herbivores, plants emit volatiles to attract parasitoids and predators of herbivores. However, our understanding of the effect of plant volatiles on the subsequent behaviour of conspecific parasitoids when herbivores on plants are parasitized is limited. In this study, rice plants were infested with gravid females of the brown planthopper (BPH) Nilaparvata lugens for 24 hr followed by another 24 hr in which the BPH eggs on plants were permitted to be parasitized by their egg parasitoid, Anagrus nilaparvatae; volatiles from rice plants that underwent such treatment were less attractive to subsequent conspecific parasitoids compared to the volatiles from plants infested with gravid BPH females alone. Chemical analysis revealed that levels of JA and JA-Ile as well as of four volatile compounds-linalool, MeSA, α-zingiberene and an unknown compound-from plants infested with BPH and parasitized by wasps were significantly higher than levels of these compounds from BPH-infested plants. Laboratory and field bioassays revealed that one of the four increased chemicals-α-zingiberene-reduced the plant's attractiveness to the parasitoid. These results suggest that host plants can fine-tune their volatiles to help egg parasitoids distinguish host habitats with parasitized hosts from those without.

Exploiting push-pull strategy to combat the tea green leafhopper based on volatiles of Lavandula angustifolia and Flemingia macrophylla

Thirteen volatile compounds were identified from Flemingia macrophylla plants. Eight major components significantly attracted the tea green leafhoppers, Empoasca flavescens F. Based on their relative abundances, following synthetic blends were made for field experiments: 1) eight-component-attractant blend included Z-3-hexen-1-ol, Z-3-hexenyl acetate, Z-ocimene, MeSA, Z-3-hexenyl butyrate, dodecane, hexadecane and nonanal at 10, 10, 1, 11, 2, 6, 2 and 4 mg mL−1 in n-hexane, respectively; 2) four-component-attractant blend #1 contained hexadecane, Z-3-hexenyl acetate, Z-3-hexen-1-ol and nonanal at 2, 10, 10 and 4 mg mL−1 in n-hexane, respectively; 3) four-component-attractant blend #2 contained hexadecane, Z-3-hexenyl acetate, Z-3-hexen-1-ol and MeSA at 2, 10, 10 and 11 mg mL−1 in n-hexane, respectively. Thymol and 1-methoxy-4-methyl-2-(1-methylethyl)-benzene, identified from Lavandula angustifolia aeration samples, significantly repelled the leafhopper as strong repellents when tested alone or in combination at 10 mg mL−1. For field bioassays, each attractant lure was attached to a bud green sticky board hung from a bamboo stick at above tea plant level for catching the leafhoppers, whereas the repellent dispenser was tied to a tea branch inside tea clump for pushing the leafhoppers away from tea clumps. The results showed that the eight-component-attractant blend caught similar numbers of the leafhopper as did the four-component-attractant blend #1 at about 53–79 leafhoppers/trap/day, which were significantly higher than those on the hexane-control bud green sticky boards. Average leafhopper catches from un-baited sticky boards were about 51–73 leafhoppers/trap/day when pushed by the repellents placed inside tea plants, with the two-component-repellent blend being more effective than their single components. When the two-component-repellent blend was further tested with the three attractant blends in a push-pull fashion, average trap catches ranged from 62 to 92 leafhoppers/trap/day. Control efficacy on the leafhoppers within the push-pull zones increased progressively from day 1 (43%) to day 5 (73%). This push-pull approach might have a great potential as a green control strategy for combating the tea green leafhoppers.

Olive Fruit Fly, Bactrocera oleae (Diptera: Tephritidae), Attraction to Volatile Compounds Produced by Host and Insect-Associated Yeast Strains.

The olive fruit fly, Bactrocera oleae (Rossi), is one of the most damaging insect pests of olives worldwide, requiring the use of insecticides for fruit protection in many orchards. Olive fruit flies are attracted to volatile composunds, including a female-produced pheromone, and host-plant and bacterial volatiles. Preliminary laboratory bioassays were conducted for olive fruit fly attraction to over 130 yeast strains from among 400 that were isolated from B. oleae adults and larvae or other insects, infested olives, and potential feeding sites. Kuraishia capsulata, Scheffersomyces ergatensis, Peterozyma xylosa, Wickerhamomyces subpelliculosus, and Lachancea thermotolerans appeared to attract B. oleae as well or better than did torula yeast pellets (Cyberlindnera jadinii; syn. Candida utilis). Volatile compounds emitted by these yeast strains were chemically identified, and included isobutanol, isoamyl alcohol, 2-phenethyl alcohol, isobutyl acetate, and 2-phenethyl acetate. The behavioral response of B. oleae adults to these volatile compounds at three concentrations was tested in a laboratory Y-tube olfactometer. The same volatile compounds were also tested in the field. Isoamyl alcohol was more attractive than the other compounds tested in both laboratory and field bioassays. Isobutanol was not attractive to B. oleae in either laboratory bioassay or field bioassay. Identifying yeast volatiles attractive to the olive fruit fly may lead to development of a more effective lure for detection, monitoring, and possibly control of B. oleae.

Identification and field verification of aggregation-sex pheromone from the predaceous bug, Arma chinensis

Arma chinensis is a predaceous insect species that can effectively suppress a wide range of agricultural and forest insect pests in the orders Lepidoptera, Coleoptera, Hymenoptera and Hemiptera in Northeast Asia. Adult A. chinensis males produce an aggregation-sex pheromone from dorsal abdominal glands and artificial aggregation-sex pheromone can attract adults of both sexes. The aggregation-sex pheromone consists of (E)-2-hexenal, (E)-2-hexen-1-ol, benzaldehyde and benzyl alcohol. Both antennae and proboscises of A. chinensis females and males responded to components from male dorsal abdominal gland extracts. (E)-2-hexenal and benzaldehyde elicited significantly higher EAG responses than those with (E)-2-hexen-1-ol and benzyl alcohol. Benzyl alcohol elicited the weakest EAG responses, although benzyl alcohol was the most abundant of the four major components in male dorsal abdominal gland extracts. A field bioassay using trap catches demonstrated that (E)-2-hexenal and benzyl alcohol were key components of the pheromone for catching conspecific adults. Single pheromone components were the least attractive to A. chinensis in the field.

Pathogenicity of the entomopathogenic fungus, Beauveria bassiana (Bals.) Vuill. endophytic and a soil isolate against the squash beetle, Epilachna chrysomelina (F.) (Coleoptera: Coccinellidae)

Laboratory and field bioassays were conducted to evaluate the pathogenicity of an endophytic and a soil isolate of the entomopathogenic fungus, Beauveria bassiana (Bals.) Vuill. against different stages of squash beetle, Epilachna chrysomelina (F.) (Coleoptera: Coccinellidae). Both isolates were identified by ITS rDNA sequence analysis. Both isolates were pathogenic to the squash beetle; however, their potential was different according to the conidia concentration and the exposure period. Three days post treatment, (100%) mortality rate was obtained, when the first and second larval instars were treated by the B. bassiana ES (soil isolate) compared to 83.67 and 72.60%, respectively when treated with the endophytic isolate. A percentage of 17.67% malformation occurred among the adults that emerged from treated pupae. The highest mortality percentage under field conditions were 28.67 and 22.33% for larvae and adults, respectively.

Effective Biopesticides and Biostimulants to Reduce Aflatoxins in Maize Fields.

The presence of ear rots in maize caused by Aspergillus flavus that are also associated with the production of aflatoxins has evolved into an increasing problem over the last few years. Since no commercial biological control products are still available to control A. flavus in maize in Europe, this study targets to the evaluation of six biopesticides/biostimulants (Botector®, Mycostop®, Serenade Max®, Trianum®, Vacciplant®, and zeolite) for the control of A. flavus and the derived aflatoxins in in vitro and maize field bioassays. Mycostop®, Serenade Max®, Vacciplant®, and zeolite reduced significantly A. flavus conidia production by 38.8–63.1%, and most of them were able to reduce aflatoxin B1 (AFB1) production in laboratory studies. Mycostop®, Trianum®, and Botector® were effective in reducing AFB1, in vitro. In the field, Mycostop® and Botector® treatments resulted in significant reduction of the disease severity (16.5 and 21.9%, respectively) and decreased significantly AFB1 content in maize kernels by 43.05 and 43.09%, respectively. For the first time, these results demonstrated the potential of commercial non-chemical products to suppress disease symptoms and aflatoxin content caused by A. flavus in maize under laboratory and field conditions.

A new synthetic lure for management of the invasive giant African snail, Lissachatina fulica.

Synthetic chemical lures mimicking pheromones or food attractants are essential tools in eradication programs for invasive species. However, their uses in programs aiming to control or eradicate terrestrial gastropods are largely unexplored. The goal of this study was to find a synthetic attractant that could aid in the eradication or management of the giant African snail (Lissachatina fulica). Field studies in Hawaii showed that a commercial papaya-flavored oil attracted snails. Analysis of the odor profile of the oil identified a total of 22 chemicals, which comprised > 98% of the volatile compounds emitted by the oil. A synthetic blend was reconstructed that mirrored the release rates of the papaya oil odors. In laboratory and field bioassays, the reconstructed blend, applied to cotton wicks as water and canola oil or water and mineral emulsions, attracted more snails than the water and oil emulsion control wicks. Field studies in Hawaii and Florida showed that the reconstructed blend in an oil emulsion was not attractive to non-target species such as butterflies or bees. The snails were attracted from distances > 1 m and entered traps baited with the attractant emulsion. When tested in the South Florida giant African snail eradication program, direct ground application of the reconstructed papaya-flavored oil emulsion increased the number of snails killed by over 87% compared to water emulsion controls. Integrating tactics using the synthetic papaya oil attractant into control measures should increase the effectiveness of eradication and management programs.

Biomimetic Approaches for the Development of New Antifouling Solutions: Study of Incorporation of Macroalgae and Sponge Extracts for the Development of New Environmentally-Friendly Coatings.

Biofouling causes major economic losses in the maritime industry. In our site study, the Bay of La Paz (Gulf of California), biofouling on immersed structures is a major problem and is treated mostly with copper-based antifouling paints. Due to the known environmental effect of such treatments, the search for environmentally friendly alternatives in this zone of high biodiversity is a priority to ensure the conservation and protection of species. The aim of this work was to link chemical ecology to marine biotechnology: indeed, the natural defense of macroalgae and sponge was evaluated against biofoulers (biofilm and macrofoulers) from the same geographical zone, and some coatings formulation was done for field assays. Our approach combines in vitro and field bioassays to ensure the selection of the best AF agent prospects. The 1st step consisted of the selection of macroalgae (5 species) and sponges (2 species) with surfaces harboring a low level of colonizers; then extracts were prepared and assayed for toxicity against Artemia, activity towards key marine bacteria involved in biofilm formation in the Bay of La Paz, and the potency to inhibit adhesion of macroorganisms (phenoloxidase assays). The most active and non-toxic extracts were further studied for biofouling activity in the adhesion of the bacteria involved in biofilm formation and through incorporation in marine coatings which were immersed in La Paz Bay during 40 days. In vitro assays demonstrated that extracts of Laurencia gardneri, Sargassum horridum (macroalgae), Haliclona caerulea and Ircinia sp. (sponges) were the most promising. The field test results were of high interest as the best formulation were composed of extracts of H. caerulea and S. horridum and led to a reduction of 32% of biofouling compared with the control.

Identification and Characterization of the Pheromones in the Minute Pirate Bug Orius sauteri (Heteroptera: Anthocoridae).

The flower bug Orius sauteri is a generalist predator that occurs throughout Japan, and is a promising indigenous natural enemy for micro-pests such as thrips, aphids, and spider mites. We aimed to manipulate the attraction, dispersal, and settlement behavior of Orius bugs using natural chemical substances emitted by the bugs themselves. To identify potential candidates, we screened components in the whole-body extract of O. sauteri based on antennal response and then determined their chemical structure. A gas chromatograph electroantennographic detector (GC/EAD) indicated that the antennae of males responded to two components in the extract of females. GC/mass spectrometry (MS) showed that these two components were octenal and octadienal. Derivatization or GC-FT-IR analysis identified these components as (E)-2-octenal and (E)-2,7-octadienal. To assess the effect of these components on O. sauteri behavior, we conducted two assays. A field bioassay demonstrated that a blend of the two components functioned as a sex pheromone, and a dispersal assay showed that (E)-2-octenal generated a dose-dependent dispersal response. Our study will provide baseline information for enhancing the retention of O. sauteri on important commercial crops to prey on pest species.

Phototoxicity Assessments of Field Sites in Barataria Bay, Louisiana, USA, and Heavily Weathered Macondo Crude Oil: 4 Years after the Deepwater Horizon Oil Spill.

The Deepwater Horizon oil spill resulted in the release of large amounts of crude oil into waters of the Gulf of Mexico (USA). A significant portion of the oil reached coastal waters and shorelines where aquatic organisms reside. Four years after the spill, oil remains in small quantities along the coast. Given the high volume of oil coupled with the high ultraviolet light intensities of the Gulf of Mexico, continued polycyclic aromatic hydrocarbon phototoxicity may be occurring in the Gulf region. The objective of the present study was to determine the potential for phototoxicity at 5 field sites (oiled, remediated, and unoiled) in Barataria Bay (LA, USA) to caged mysid shrimp and sheepshead minnows and to evaluate the phototoxic potential of field-collected oil water accommodated fractions (WAFs). Water chemistries were similar between field-collected oil WAFs and ambient waters, excluding the most oiled field site. Field bioassays indicated no phototoxic risk of heavily weathered crude oil under the highly turbid conditions present during the study. Laboratory WAFs of field-collected oil resulted in phototoxicity to mysid shrimp, suggesting a potential for phototoxicity of heavily weathered crude oil remaining in the Gulf of Mexico. Environ Toxicol Chem 2019;38:1811-1819. © 2019 SETAC.

Time-series transcriptome provides insights into the gene regulation network involved in the volatile terpenoid metabolism during the flower development of lavender

BackgroundEssential oils (EOs) of Lavandula angustifolia, mainly consist of monoterpenoids and sesquiterpenoids, are of great commercial value. The multi-flower spiciform thyrse of lavender not only determines the output of EOs but also reflects an environmental adaption strategy. With the flower development and blossom in turn, the fluctuation of the volatile terpenoids displayed a regular change at each axis. However, the molecular mechanism underlying the regulation of volatile terpenoids during the process of flowering is poorly understood in lavender. Here, we combine metabolite and RNA-Seq analyses of flowers of five developmental stages at first- and second-axis (FFDSFSA) and initial flower bud (FB0) to discover the active terpenoid biosynthesis as well as flowering-related genes.ResultsA total of 56 mono- and sesquiterpenoids were identified in the EOs of L. angustifolia ‘JX-2’. FB0’ EO consists of 55 compounds and the two highest compounds, β-trans-ocimene (20.57%) and (+)-R-limonene (17.00%), can get rid of 74.71 and 78.41% aphids in Y-tube olfactometer experiments, respectively. With sequential and successive blossoms, temporally regulated volatiles were linked to pollinator attraction in field and olfaction bioassays. In three characteristic compounds of FFDSFSA’ EOs, linalyl acetate (72.73%) and lavandulyl acetate (72.09%) attracted more bees than linalool (45.35%). Many transcripts related to flowering time and volatile terpenoid metabolism expressed differently during the flower development. Similar metabolic and transcriptomic profiles were observed when florets from the two axes were maintained at the same maturity grade. Besides both compounds and differentially expressed genes were rich in FB0, most volatile compounds were significantly correlated with FB0-specific gene module. Most key regulators related to flowering and terpenoid metabolism were interconnected in the subnetwork of FB0-specific module, suggesting the cross-talk between the two biological processes to some degree.ConclusionsCharacteristic compounds and gene expression profile of FB0 exhibit ecological value in pest control. The precise control of each-axis flowering and regular emissions at transcriptional and metabolic level are important to pollinators attraction for lavender. Our study sheds new light on lavender maximizes its fitness from “gene-volatile terpenoid-insect” three layers.

Common Cerambycid Pheromone Components as Attractants for Longhorn Beetles (Cerambycidae) Breeding in Ephemeral Oak Substrates in Northern Europe

Longhorn beetles are ecologically important insects in forest ecosystems as decomposers of woody substrates, microhabitat engineers, and as components of forest food webs. These species can be greatly affected both positively and negatively by modern forestry management practices, and should be monitored accordingly. Through headspace sampling, coupled gas chromatography-electroantennography, gas chromatography-mass spectrometry, and field bioassays, we identified two compounds, 2-methyl-1-butanol and 3-hydroxy-2-hexanone, that constitute aggregation-sex pheromone attractants of three cerambycid species which breed primarily in different types of fresh, recently dead oak wood in Northern Europe: Pyrrhidium sanguineum (L.), Phymatodes alni ssp. alni (L.), and Phymatodes testaceus (L.) (Cerambycinae: Callidiini). Analyses of headspace volatiles collected from live insects indicated that the male-produced aggregation-sex pheromone of P. sanguineum is a 1–15:100 blend of (R)-2-methyl-1-butanol and (R)-3-hydroxy-2-hexanone, whereas the corresponding ratios for P. alni were 70–110:100. In field bioassays, adult P. sanguineum and P. alni were significantly attracted to multiple blends with varying ratios of the two compounds. When tested individually, the compounds were minimally attractive. In contrast, adult P. testaceus exhibited nonspecific attraction to both of the individual compounds and to different blends, despite the hydroxyketone not being part of its pheromone, which consists of (R)-2-methyl-1-butanol alone. Overall, our results suggest that a blend of 50:100 of racemic 2-methyl-1-butanol and 3-hydroxy-2-hexanone is appropriate for parallel, cost-efficient pheromone-based monitoring of all three species. In particular, these species could serve as useful indicators of how modern forestry practices affect a whole guild of saproxylic insects that require ephemeral deadwood substrates for successful breeding.

Field Efficacy Trials of Aerial Ultra-Low-Volume Application of Insecticides Against Caged Aedes aegypti in Mexico.

We evaluated the efficacy of aerial ultra-low-volume (ULV) insecticide spraying in field bioassays with caged Aedes aegypti in May 2017 in Puerto Vallarta, Jalisco, Mexico. The insecticides tested included an organophosphate (Mosquitocida UNO ULV) and a neonicotinoid-pyrethroid combination (Cielo). Two Ae. aegypti populations were evaluated: a field pyrethroid-resistant local strain (Puerto Vallarta) and an insecticide-susceptible laboratory strain (New Orleans). Knockdown after 1 h by both products was ≥97.0%, and mortality after 24 h was ≥98% for the susceptible laboratory strain. Knockdown of the local Puerto Vallarta field strain by both products after 1 h was ≥96.5%; and mosquito mortality after 24 h was also very high (≥98%). Meteorological conditions during this evaluation were favorable for aerial mosquito control and represented conditions that typically occur during adulticide space spray applications. Temperature oscillated between 24°C and 26°C with winds between 6 and 10 km/h. The majority of droplets met the droplet distribution criteria required for the insecticides. The evaluation demonstrated an acceptable performance of both products for Ae. aegypti control when applied undiluted at a rate of 199.4 ml/ha and 73.07 ml/ha for Mosquitocida UNO ULV and Cielo, respectively. The volume median diameter (VMD) droplet size was characterized at 31.3 μm and 37.3 μm, respectively.

Evaluation of insecticides for control of the spotted lanternfly, Lycorma delicatula, (Hemiptera: Fulgoridae), a new pest of fruit in the Northeastern U.S.

The spotted lanternfly, Lycorma delicatula (White) (Hemiptera: Fulgoridae), was first detected in the United States in southeastern Pennsylvania in late 2014. Since then, the range of this polyphagous pest has increased to multiple states in the Northeastern U.S., threatening many agricultural commodities, including grape and tree fruit. Several insecticides were tested for residual efficacy on eggs, nymphs, and adult L. delicatula. In both laboratory and field bioassays on L. delicatula egg masses, chlorpyrifos was the only compound to provide 100% mortality and paraffinic oil offered intermediate mortality up to 71%. In semi-field and field bioassays against L. delicatula nymphs and adults, several compounds from multiple insecticide classes, including pyrethroids, neonicotinoids, carbamates, and organophosphates, had excellent knockdown activity. However, only thiamethoxam and bifenthrin offered control of 50% or greater up to 14 days after the application for adults. None of the OMRI-listed compounds evaluated in this study provided effective control, indicating anticipated difficulty among organic producers in reducing damage from this new and important pest. As L. delicatula continues to expand its geographic range, we may have to be reliant on chemical control until biological or other cultural control measures are discovered and implemented. These data have helped to formulate pest management programs as a first response to this invasive insect.