Sequential Isolation of Essential Oils Repellent to the Red Palm Weevil Rhynchophorus ferrugineus Olivier (Coleoptera: Curculionidae).

The push-pull approach using semiochemicals in pest control requires both an attractant and a repellent. Many previous studies have arbitrarily tested one or more known insect repellents or plant essential oils (EOs) hoping to find repellents of an insect pest. We used a comprehensive approach that synergistically tests in the field numerous natural volatiles from commercial EOs to identify repellents of the red palm weevil Rhynchophorus ferrugineus (Coleoptera: Curculionidae), a worldwide pest of palms and date palms.

Absolute Configuration of the Spherical Mealybug Sex Pheromone, γ-Necrodyl Isobutyrate: Chemoenzymatic Synthesis and Bioassays.

The spherical mealybug, (Hemiptera: Pseudococcidae), is a major global pest causing feeding damage to leaves and fruits of citrus varieties, soybean, mango, pomegranate, and grapevines. Females of the mealybug release a sex pheromone that was identified recently as a mixture of γ-necrodyl isobutyrate and γ-necrodol. The identification required synthesis based on a natural source of -α-necrodol, of unknown chirality, obtained from essential oil of Spanish lavender, .

Development of an immunoassay and a sol-gel-based immunoaffinity cleanup method for coplanar polychlorinated biphenyls from soil and sediment samples.

Two polychlorinated biphenyls (PCB) enzyme linked immunosorbent assays (ELISAs) were developed using goat PCB purified immunoglobulin (IgG) antibodies (Abs). The IgGs exhibited the highest affinity toward PCB-77 (24 ng mL(-1)) with sensitivities in the range of 6-11 ng mL(-1). The Abs cross-reacted with PCB-126 and the heptachlorodibenzofuran 1,2,3,4,6,7,8-HpCDF but not with PCB-169, PCB-118, Aroclor 1232, 1248, 1260 or the hexachlorodibenzofuran 2,3,4,6,7,8-HxCDF.

Bioavailability of backbone cyclic PK/PBAN neuropeptide antagonists--inhibition of sex pheromone biosynthesis elicited by the natural mechanism in Heliothis peltigera females.

The bioavailability (i.e. ability to penetrate the insect cuticle, to reach the target organ and to exert bioactivity) of two backbone cyclic (BBC) pyrokinin/pheromone biosynthesis-activating neuropeptide (PK/PBAN) antagonistic peptides was tested by applying them topically to Heliothis peltigera females and monitoring the resulting inhibition of sex pheromone production elicited by the natural (endogenous) mechanism during scotophase.

A novel dihydroimidazoline, trans-Pro mimetic analog is a selective PK/PBAN agonist.

The pyrokinin/pheromone biosynthesis activating neuropeptide (PK/PBAN) family plays a significant role in the regulation of reproductive and developmental processes in a variety of insects. A transPro, type I beta-turn has been previously identified as important for the activity of PK/PBAN peptides. A PK/PBAN analog (PPK-Jo) incorporating a novel dihydroimidazole transPro mimetic motif was evaluated in four PK/PBAN bioassays (pheromonotropic, melanotropic, pupariation and hindgut myotropic).

PBAN receptor: employment of anti-receptor antibodies for its characterization and for development of a microplate binding assay.

This study describes generation of an anti-PBAN receptor (PBAN-R) antiserum and its employment for the characterization of the PK/PBAN-R(s). The antiserum recognized, in a specific and dose-dependent manner, the presence of PBAN-R in pheromone gland membrane preparations of three female moths: Heliothis peltigera, Helicoverpa armigera and Spodoptera littoralis. It also reacted specifically with the S.

Bioavailability of beta-amino acid and C-terminally derived PK/PBAN analogs.

The ability of linear beta-amino acid substituted peptides (PK-betaA-1: Ac-YFT[beta(3)P]RLa; PK-betaA-2: Ac-Y[beta(3)homoF]TPRLa; PK-betaA-3: Ac-Y[beta(3)F]TPRLa; PK-betaA-4: Ac-[beta(3)F]FT[beta(3)P]RLa) and unsubstituted analogs (Ac-YFTPRLa and YFTPRLa) of the pyrokinin(PK)/pheromone biosynthesis-activating neuropeptide (PBAN) family to penetrate the insect cuticle and exert biological activity (i.e., stimulate sex pheromone biosynthesis), was tested by topical application on Heliothis peltigera moths.

Bioavailability of insect neuropeptides: the PK/PBAN family as a case study.

The ability of unmodified linear peptides to penetrate the insect cuticle and exert bioactivity (e.g., stimulation of sex pheromone biosynthesis) was tested by topical application onto Heliothis peltigera moths of four insect neuropeptides (Nps) of the pyrokinin (PK)/pheromone biosynthesis activating neuropeptide (PBAN) family: Helicoverpa zea PBAN (Hez-PBAN), Pseudaletia (Mythimna) separata pheromonotropin (PT), Leucophaea maderae PK (LPK) and Locusta migratoria myotropin (Lom-MT-II).

Evaluation of a PK/PBAN analog with an (E)-alkene, trans-Pro isostere identifies the Pro orientation for activity in four diverse PK/PBAN bioassays.

The pyrokinin/pheromone biosynthesis activating neuropeptide (PK/PBAN) family plays a multifunctional role in an array of important physiological processes in a variety of insects. An active core analog containing an (E)-alkene, trans-Pro isosteric component was evaluated in four disparate PK/PBAN bioassays in four different insect species. These bioassays include pheromone biosynthesis in the moth Heliothis peltigera, melanization in the larval Spodoptera littoralis, pupariation acceleration in the larval fly Neobellieria bullata, and hindgut contraction in the cockroach Leucophaea maderae.

Biostable beta-amino acid PK/PBAN analogs: agonist and antagonist properties.

The pyrokinin/pheromone biosynthesis activating neuropeptide (PK/PBAN) family plays a significant role in a multifunctional array of important physiological processes in insects. PK/PBAN analogs incorporating beta-amino acids were synthesized and evaluated in a pheromonotropic assay in Heliothis peltigera, a melanotropic assay in Spodoptera littoralis, a pupariation assay in Neobellieria bullata, and a hindgut contractile assay in Leucophaea maderae. Two analogs (PK-betaA-1 and PK-betaA-4) demonstrate greatly enhanced resistance to the peptidases neprilysin and angiotensin converting enzyme that are shown to degrade the natural peptides.

An amphiphilic, PK/PBAN analog is a selective pheromonotropic antagonist that penetrates the cuticle of a heliothine insect.

A linear pyrokinin (PK)/pheromone biosynthesis activating neuropeptide (PBAN) antagonist lead (RYF[dF]PRLa) was structurally modified to impart amphiphilic properties to enhance its ability to transmigrate the hydrophobic cuticle of noctuid moth species and yet retain aqueous solubility in the hemolymph to reach target PK/PBAN receptors within the internal insect environment. The resulting novel PK/PBAN analog, Hex-Suc-A[dF]PRLa (PPK-AA), was synthesized and evaluated as an antagonist in a pheromonotropic assay in Heliothis peltigera against 4 natural PK/PBAN peptide elicitors (PBAN; pheromonotropin, PT; myotropin, MT; leucopyrokinin, LPK) and in a melanotropic assay in Spodoptera littoralis against 3 natural PK/PBAN peptide elicitors (PBAN, PT, LPK). The analog proved to be a potent and efficacious inhibitor of sex pheromone biosynthesis elicited by PBAN (84% at 100 pmol) and PT (54% at 100 pmol), but not by MT and LPK.

Inhibition of PK/PBAN-mediated functions in insects: discovery of selective and non-selective inhibitors.

The antagonistic properties of a few linear and backbone cyclic (BBC) conformationally constraint peptide libraries and their analogs, were tested for the ability to inhibit pyrokinin/pheromone biosynthesis activating neuropeptide (PK/PBAN) mediated functions: sex pheromone biosynthesis in Heliothis peltigera female moths, cuticular melanization in Spodoptera littoralis larvae, pupariation in the fleshfly Neobellieria bullata and hindgut contraction in Leucophaea maderae, elicited by exogenously injected PBAN, pheromonotropin (PT), leucopyrokinin (LPK), myotropin (MT) or by the endogenous peptides. The data revealed differential inhibitory patterns within the same assay with different elicitors (in both the pheromonotropic and melanotropic assays) and among the different functions and disclosed selective antagonists, hinting at the possibility that the receptors that mediate those functions may differ from one another structurally.

Backbone cyclic pheromone biosynthesis activating neuropeptide (PBAN) antagonists: inhibition of melanization in the moth Spodoptera littoralis (Insecta, Lepidoptera).

Antagonistic and agonistic activities of backbone cyclic (BBC) pheromone biosynthesis activating neuropeptide (PBAN) analogues were evaluated in an attempt to identify potent melanotropic antagonists, to gain an insight into their structure-activity relationship (SAR), and to discover molecules with selective and non-selective melanotropic and pheromonotropic properties. Eight potent melanotropic BBC antagonists and seven agonists were disclosed. SAR studies revealed that the structural requirements of the melanotropic and pheromonotropic agonists and antagonists are different.

PBAN selective antagonists: inhibition of PBAN induced cuticular melanization and sex pheromone biosynthesis in moths.

A D-Phe scan (sequential D-Phe replacement) library of linear peptides, synthesized on the basis of a slightly modified active sequence of PBAN (YFSPRL-amide) was employed to detect potential inhibitors of cuticular melanization in Spodoptera littoralis larvae and to compare their stimulatory and inhibitory melanization activity with their pheromonotropic agonistic and antagonistic activities. A quantitative melanotropic assay was used to monitor the extent of cuticular melanization elicited by Hez-PBAN1-33NH2 in S. littoralis larvae in the presence and absence of the D-Phe peptides.

Histochemical localization of the PBAN receptor in the pheromone gland of Heliothis peltigera.

The presence of the pyrokinin (PK)/ Pheromone biosynthesis activating neuropeptide (PBAN) receptor in pheromone gland cells of Heliothis peltigera females was demonstrated, and its spatial distribution in the ovipositor was visualized with two photo-affinity biotinilated ligands: BpaPBAN1-33NH(2) and BpaArg(27)-PBAN28-33NH(2). Light microscopy histological studies revealed that the gland is contained within the inter-segmental membrane (ISM) between the 8th and 9th abdominal segments. The gland was found to be composed of a single layer of columnar epithelial cells positioned under the inter-segmental cuticle.