Mass spectral determination of phenylacetonitrile (PAN) levels in body tissues of adult desert locust, Schistocerca gregaria

Wings and legs of the gregarious desert locust, Schistocerca gregaria have been shown to be release sites of phenylacetonitrile (PAN), the major adult male-produced pheromone. However, there is limited information on the distribution of PAN within the locust. Here we show, using gas chromatography–mass spectrometry (GC–MS), that PAN occurs in nearly all body parts of both adult males and females of the locust in varying amounts. PAN was 20-fold more concentrated in males than in females. In females, PAN was concentrated more in the tarsal segments. The greatest amounts of PAN were in 2- and 3-week old female and male body parts, respectively. No trace of PAN was found in similar ages and sexes of the solitarious phase desert locust. Our results show that PAN is distributed in the body matrix of both sexes of gregarious phase locusts and suggest that no specific tissue is responsible for biosynthesis of the pheromone.http://www.elsevier.com/locate/jinsphysab201

Common host-derived chemicals increase catches of disease-transmitting mosquitoes and can improve early warning systems for rift valley fever virus

Rift Valley fever (RVF), a mosquito-borne zoonosis, is a major public health and veterinary problem in sub-Saharan Africa. Surveillance to monitor mosquito populations during the inter-epidemic period (IEP) and viral activity in these vectors is critical to informing public health decisions for early warning and control of the disease. Using a combination of field bioassays, electrophysiological and chemical analyses we demonstrated that skin-derived aldehydes (heptanal, octanal, nonanal, decanal) common to RVF virus (RVFV) hosts including sheep, cow, donkey, goat and human serve as potent attractants for RVFV mosquito vectors. Furthermore, a blend formulated from the four aldehydes and combined with CO2- baited CDC trap without a light bulb doubled to tripled trap captures compared to control traps baited with CO2 alone. Our results reveal that (a) because of the commonality of the host chemical signature required for attraction, the host-vector interaction appears to favor the mosquito vector allowing it to find and opportunistically feed on a wide range of mammalian hosts of the disease, and (b) the sensitivity, specificity and superiority of this trapping system offers the potential for its wider use in surveillance programs for RVFV mosquito vectors especially during the IEP.The support through a scholarship to DPT by the German Academic Exchange Service (DAAD) is greatly acknowledged. This research was funded by Google.org, the philanthropic arm of Google. We are grateful to Francis Mulwa and James Wauna for assistance in field experiments and other individuals at the communities who helped in the same capacity. We acknowledge the technical assistance of Dunston Betti, John Gachoya and Joel Lutomiah, Kenya Medical Research Institute (KEMRI) and James Mutysia of Walter Reed Project (WRP), Nairobi. Our sincere gratitude to Dr. Salifu Daisy, Mrs Caroline Tigoi, and Mr. Benedict Orindi, International Centre of Insect Physiology and Ecology (icipe), Nairobi. We appreciate the services of the chiefs at the trapping communities both at Marigat and Ijara districts. The Arbovirus Incidence and Diversity Project consortium-icipe, International Livestock Research Institute (ILRI), Kenya Agricultural Research Institute (KARI), Kenya Ministry of Livestock-Department of Veterinary Services (DVS), KEMRI, Kenya Ministry of Public Health and Sanitation and Kenya Wildlife Service (KWS).www.plosntds.orgam2013ab201

Response of the small hive beetle (Aethina tumida) to honey bee (Apis mellifera) and beehive-produced volatiles

The response of male and female Small Hive Beetle (SHB), Aethina tumida, to air-borne volatiles from adult worker bees, (Apis mellifera), pollen, unripe honey, beeswax, wax by-products (“slumgum"), and bee brood, was investigated in olfactometric and flight-tunnel choice bioassays. In both bioassay systems, males and females responded strongly to the volatiles from worker bees, freshly collected pollen and slumgum but not to those from commercially available pollen, beeswax and bee brood. The response to pollen volatiles was dose dependent, while response to volatiles from worker bees increased with both the number and age of the bees. Females were more responsive than males to the different volatile sources, with greater response in tests with unripe honey. In flight-tunnel choice tests, Super Q-trapped volatiles from worker bees elicited a response comparable to the response to living workers, while trapped volatiles from other sources were not attractive

Response of the small hive beetle (Aethina tumida) to a blend of chemicals identified from honeybee (Apis mellifera) volatiles

Coupled gas chromatographic-electroantennographic detection (GC-EAD) analyses of Super Q collected worker honey bee volatiles revealed several components that elicited antennal responses by the small hive beetle Aethina tumida. However, GC-MS analysis showed that eight of these EAD-active components dominated the volatile profile released into a wind tunnel by living adult worker honeybees and rubber septa impregnated with a Super Q extract of the volatiles of the bees in a 15-min bioassay. These components were identified as isopentyl acetate, 2-heptanone, octanal, hexyl acetate, nonanal, 2-nonanone, methyl benzoate and decanal. In dual-choice wind tunnel bioassays, the Super Q extract and a blend of the eight components elicited dose-dependent upwind responses from beetles relative to a solvent control. At 375-bee day equivalents, the Super Q extract and the 8-component blend elicited 76 and 74% upwind response, respectively, which compared with 84% response from approx. 150-200 living worker honey bees. In contrast, the Super Q extract and the 8-component blend lured only approx. 12 and 3% of beetles, respectively, into a trap compared to 48% by the odor from living adult worker bees

Biosynthetic Pathway of Insect Juvenile Hormone III in Cell Suspension Cultures of the Sedge Cyperus iria

In most insect species, juvenile hormones regulate critical physiological processes such as metamorphosis and reproduction. In insects, these sesquiterpenoids are synthesized by retrocerebral endocrine organs, the corpora allata, via the classical mevalonate (MVA) pathway. One of these compounds, juvenile hormone III (JH III), has also been identified in the sedge Cyperus iria. In higher plants, biosynthesis of the sesquiterpenoid backbone may proceed through two distinct pathways: the MVA pathway or the 2C-methyl erythritol 4-phosphate pathway or through a combination of both pathways. Cell suspension cultures of C. iria were used to elucidate the biosynthetic pathway of JH III in the plant. Enzyme inhibition and labeling studies conclusively demonstrated that the biosynthesis of the sesquiterpenoid backbone of JH III proceeds via the MVA pathway. Inhibitor and precursor feeding studies also suggest that later steps of JH III biosynthesis in C. iria are similar to the insect pathway and that the final enzymatic reaction in JH III biosynthesis is catalyzed by a cytochrome P450 monooxygenase

Cowpea Chloroplastic ATP Synthase Is the Source of Multiple Plant Defense Elicitors during Insect Herbivory12[W][OA]

In cowpea (Vigna unguiculata), fall armyworm (Spodoptera frugiperda) herbivory and oral secretions (OS) elicit phytohormone production and volatile emission due to inceptin [Vu-In; +ICDINGVCVDA−], a peptide derived from chloroplastic ATP synthase γ-subunit (cATPC) proteins. Elicitor-induced plant volatiles can function as attractants for natural enemies of insect herbivores. We hypothesized that inceptins are gut proteolysis products and that larval OS should contain a mixture of related peptides. In this study, we identified three additional cATPC fragments, namely Vu-GE+In [+GEICDINGVCVDA−], Vu-E+In [+EICDINGVCVDA−], and Vu-In−A [+ICDINGVCVD−]. Leaf bioassays for induced ethylene (E) production demonstrated similar effective concentration50 values of 68, 45, and 87 fmol leaf−1 for Vu-In, Vu-E+In, and Vu-GE+In, respectively; however, Vu-In−A proved inactive. Shortly following ingestion of recombinant proteins harboring cATPC sequences, larval OS revealed similar concentrations of the three elicitors with 80% of the potential inceptin-related peptides recovered. Rapidly shifting peptide ratios over time were consistent with continued proteolysis and preferential stability of inceptin. Likewise, larvae ingesting host plants with inceptin precursors containing an internal trypsin cleavage site rapidly lost OS-based elicitor activity. OS containing inceptin elicited a rapid and sequential induction of defense-related phytohormones jasmonic acid, E, and salicylic acid at 30, 120, and 240 min, respectively, and also the volatile (E)-4,8-dimethyl-1,3,7-nonatriene. Similar to established peptide signals such as systemin and flg22, amino acid substitutions of Vu-In demonstrate an essential role for aspartic acid residues and an unaltered C terminus. In cowpea, insect gut proteolysis following herbivory generates inappropriate fragments of an essential metabolic enzyme enabling plant non-self-recognition

Composition of volatiles from fermenting pollen dough and attractiveness to the small hive beetle Aethina tumida, a parasite of the honeybee Apis mellifera

The response of the small hive beetle (SHB), Aethina tumida Murray, to volatiles from a pollen-based diet conditioned by the feeding of 100 adult virgin female or male SHBs (4–8 weeks old) for 1, 3, 7 or 14 days is described and compared to that of the same diet inoculated with the yeast Kodamaea ohmeri (NRRL Y-30722), isolated from the beetle. In a wind tunnel, volatiles from pollen dough conditioned by beetles of either sex for 3 or 7 days lured significantly more beetles into traps than volatiles from unconditioned dough. In contrast, trap captures with volatiles from dough conditioned for 1 and 14 days were weakly attractive. In cage bioassays, when naïve, unfed, virgin, SHBs (3–4 days old) were given a choice between yeast-inoculated pollen dough and non-inoculated dough, the responses were similar to those obtained in the wind tunnel with dough conditioned by SHBs for 3 and 7 days. Chemical analysis revealed high levels of fermentation-related products in volatiles that attracted the beetle