Truck-Mounted Area-Wide Application of Pyriproxyfen Targeting Aedes aegypti and Aedes albopictus in Northeast Florida.

This study was conducted to determine the efficacy of truck-mounted ultra-low volume applications of pyriproxyfen against Aedes aegypti larvae in artificial water containers and wild adult Ae. albopictus populations in an urban setting. The study was conducted over a 3.5-month period (June-October 2012), during which 3 pyriproxyfen applications were conducted. Beginning 6 wk prior to the 1st pyriproxyfen spray, 10 Biogents-Sentinel® traps were used each week to survey the adult Ae. albopictus population at each experimental plot through the end of the study. The treatment and control plots contained specimen cups, each containing 10 laboratory-reared Ae. aegypti larvae, placed at 8, 15, and 23 m from the spray line. Emergence inhibition (EI) of 82% or greater was observed among Ae. aegypti larvae exposed to the 3 pyriproxyfen sprays. The EI of these same Ae. aegypti larvae at the 3 distances from the spray ranged from 84% to 92% and were not significantly different. Laboratory analysis of water samples taken from the larval cups independently confirmed the presence of pyriproxyfen. Similar levels of EI were achieved in Ae. aegypti and Ae. albopictus larvae when the measured field concentrations of pyriproxyfen were recreated in laboratory assays. Trap captures of wild adult Ae. albopictus were not markedly reduced following the 1st pyriproxyfen spray, perhaps due to heavy rainfall at the time and the lower rate of pyriproxyfen applied. Within 2 wk following Spray 2, however, Ae. albopictus collections from the treatment plot averaged approximately 50% of those from the control plot, and the reduction trend continued following Spray 3.

Insecticidal, repellent and fungicidal properties of novel trifluoromethylphenyl amides.

Twenty trifluoromethylphenyl amides were synthesized and evaluated as fungicides and as mosquito toxicants and repellents. Against Aedes aegypti larvae, N-(2,6-dichloro-4-(trifluoromethyl)phenyl)-3,5-dinitrobenzamide (1e) was the most toxic compound (24 h LC50 1940 nM), while against adults N-(2,6-dichloro-4-(trifluoromethyl)phenyl)-2,2,2-trifluoroacetamide (1c) was most active (24 h LD50 19.182 nM, 0.5 µL/insect). However, the 24 h LC50 and LD50 values of fipronil against Ae. aegypti larvae and adults were significantly lower: 13.55 nM and 0.787 × 10(-4) nM, respectively. Compound 1c was also active against Drosophila melanogaster adults with 24 h LC50 values of 5.6 and 4.9 µg/cm(2) for the Oregon-R and 1675 strains, respectively. Fipronil had LC50 values of 0.004 and 0.017 µg/cm(2) against the two strains of D. melanogaster, respectively. In repellency bioassays against female Ae. aegypti, 2,2,2-trifluoro-N-(2-(trifluoromethyl)phenyl)acetamide (4c) had the highest repellent potency with a minimum effective dosage (MED) of 0.039 µmol/cm(2) compared to DEET (MED of 0.091 µmol/cm(2)). Compound N-(2-(trifluoromethyl)phenyl)hexanamide (4a) had an MED of 0.091 µmol/cm(2) which was comparable to DEET. Compound 4c was the most potent fungicide against Phomopsis obscurans. Several trends were discerned between the structural configuration of these molecules and the effect of structural changes on toxicity and repellency. Para- or meta- trifluoromethylphenyl amides with an aromatic ring attached to the carbonyl carbon showed higher toxicity against Ae. aegypti larvae, than ortho- trifluoromethylphenyl amides. Ortho- trifluoromethylphenyl amides with trifluoromethyl or alkyl group attached to the carbonyl carbon produced higher repellent activity against female Ae. aegypti and Anopheles albimanus than meta- or para- trifluoromethylphenyl amides. The presence of 2,6-dichloro- substitution on the phenyl ring of the amide had an influence on larvicidal and repellent activity of para- trifluoromethylphenyl amides.

Ixodes scapularis tick serine proteinase inhibitor (serpin) gene family; annotation and transcriptional analysis.

BACKGROUND: Serine proteinase inhibitors (Serpins) are a large superfamily of structurally related, but functionally diverse proteins that control essential proteolytic pathways in most branches of life. Given their importance in the biology of many organisms, the concept that ticks might utilize serpins to evade host defenses and immunizing against or disrupting their functions as targets for tick control is an appealing option. RESULTS: A sequence homology search strategy has allowed us to identify at least 45 tick serpin genes in the Ixodes scapularis genome that are structurally segregated into 32 intronless and 13 intron-containing genes. Nine of the intron-containing serpins occur in a cluster of 11 genes that span 170 kb of DNA sequence. Based on consensus amino acid residues in the reactive center loop (RCL) and signal peptide scanning, 93% are putatively inhibitory while 82% are putatively extracellular. Among the 11 different amino acid residues that are predicted at the P1 sites, 16 sequences possess basic amino acid (R/K) residues. Temporal and spatial expression analyses revealed that 40 of the 45 serpins are differentially expressed in salivary glands (SG) and/or midguts (MG) of unfed and partially fed ticks. Ten of the 38 serpin genes were expressed from six to 24 hrs of feeding while six and fives genes each are predominantly or exclusively expressed in either MG and SG respectively. CONCLUSION: Given the diversity among tick species, sizes of tick serpin families are likely to be variable. However this study provides insight on the potential sizes of serpin protein families in ticks. Ticks must overcome inflammation, complement activation and blood coagulation to complete feeding. Since these pathways are regulated by serpins that have basic residues at their P1 sites, we speculate that I. scapularis may utilize some of the serpins reported in this study to manipulate host defense. We have discussed our data in the context of advances on the molecular physiology of I. scapularis. Although the paper is descriptive, this study provides the first step toward a comprehensive understanding of serpins in tick physiology.