Geographic Variation in Sexual Attraction of Spodoptera frugiperda Corn- and Rice-Strain Males to Pheromone Lures

The corn- and rice-strains of Spodoptera frugiperda exhibit several genetic and behavioral differences and appear to be undergoing ecological speciation in sympatry. Previous studies reported conflicting results when investigating male attraction to pheromone lures in different regions, but this could have been due to inter-strain and/or geographic differences. Therefore, we investigated whether corn- and rice-strain males differed in their response to different synthetic pheromone blends in different regions in North America, the Caribbean and South America. All trapped males were strain typed by two strain-specific mitochondrial DNA markers. In the first experiment, we found a nearly similar response of corn and rice-strain males to two different 4-component blends, resembling the corn- and rice-strain female blend we previously described from females in Florida. This response showed some geographic variation in fields in Canada, North Carolina, Florida, Puerto Rico, and South America (Peru, Argentina). In dose-response experiments with the critical secondary sex pheromone component (Z)-7-dodecenyl acetate (Z7-12:OAc), we found some strain-specific differences in male attraction. While the response to Z7-12:OAc varied geographically in the corn-strain, rice-strain males showed almost no variation. We also found that the minor compound (Z)-11-hexadecenyl acetate (Z11-16:OAc) did not increase attraction of both strains in Florida and of corn-strain males in Peru. In a fourth experiment, where we added the stereo-isomer of the critical sex pheromone component, (E)-7-dodecenyl acetate, to the major pheromone component (Z)-9-tetradecenyl acetate (Z9-14:OAc), we found that this compound was attractive to males in North Carolina, but not to males in Peru. Overall, our results suggest that both strains show rather geographic than strain-specific differences in their response to pheromone lures, and that regional sexual communication differences might cause geographic differentiation between populations.Fil: Unbehend, Melanie. Instituto Max Planck Institut Fur Chemische Okologie; AlemaniaFil: Hänniger, Sabine. Instituto Max Planck Institut Fur Chemische Okologie; AlemaniaFil: Vasquez, Gissella M.. University Of North Carolina; Estados UnidosFil: Juárez, María Laura. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán; ArgentinaFil: Reisig, Dominic. University Of North Carolina; Estados UnidosFil: Mcneil, Jeremy N.. University of Western Ontario. Department of Biology; CanadáFil: Meagher, Robert L.. United States Department Of Agriculture; Estados UnidosFil: Jenkins, David A.. United States Department of Agriculture; ArgentinaFil: Heckel, David G.. Instituto Max Planck Institut Fur Chemische Okologie; AlemaniaFil: Groot, Astrid T.. University Of Amsterdam; Países Bajos. Instituto Max Planck Institut Fur Chemische Okologie; Alemani

Diversity, distribution and natural Leishmania infection of sand flies from communities along the Interoceanic Highway in the Southeastern Peruvian Amazon

The Peruvian-Brazilian border is a highly endemic tegumentary leishmaniasis region in South America. The interoceanic highway is a commercial route that connects Peru and Brazil through Madre de Dios and has raised concerns about its impact on previously undisturbed areas. In order to assess leishmaniasis transmission risk along this highway, we conducted a surveillance study of the sand fly populations in this area. Sand flies were collected between 2009 and 2010 along transects at 200 m, 600 m and 1000 m from six study sites located along the highway (Iberia, La Novia, Alto Libertad, El Carmen, Florida Baja, Mazuko and Mavila) and an undisturbed area (Malinowski). Collected specimens were identified based on morphology and non-engorged females of each species were pooled and screened by kinetoplast PCR to detect natural Leishmania infections. A total of 9,023 specimens were collected belonging to 54 different Lutzomyia species including the first report of Lu. gantieri in Peru. Four species accounted for 50% of all specimens (Lutzomyia carrerai carrerai, Lu. davisi, Lu. shawi and Lu. richardwardi). El Carmen, Alto Libertad, Florida Baja and Malinowski presented higher Shannon diversity indexes (H = 2.36, 2.30, 2.17 and 2.13, respectively) than the most human disturbed sites of Mazuko and La Novia (H = 1.53 and 1.06, respectively). PCR detected 10 positive pools belonging to Lu. carrerai carrerai, Lu. yuilli yuilli, Lu. hirsuta hirsuta, Lu. (Trichophoromyia) spp., and Lu. (Lutzomyia) spp. Positive pools from 1,000 m transects had higher infectivity rates than those from 600 m and 200 m transects (9/169 = 5.3% vs 0/79 = 0% and 1/127 = 0.8%, p = 0.018). El Carmen, accounted for eight out of ten positives whereas one positive was collected in Florida Baja and Mazuko each. Our study has shown differences in sand fly diversity, abundance and species composition across and within sites. Multiple clustered Lutzomyia pools with natural Leishmania infection suggest a complex, diverse and spotty role in leishmaniasis transmission in Madre de Dios, with increased risk farther from the highway

Data from: Efficacy of Aedes aegypti control by indoor Ultra Low Volume (ULV) insecticide spraying in Iquitos, Peru

Background: Aedes aegypti is a primary vector of dengue, chikungunya, Zika, and urban yellow fever viruses. Indoor, ultra low volume (ULV) space spraying with pyrethroid insecticides is the main approach used for Ae. aegypti emergency control in many countries. Given the widespread use of this method, the lack of large-scale experiments or detailed evaluations of municipal spray programs is problematic. Methodology/Principal Findings: Two experimental evaluations of non-residual, indoor ULV pyrethroid spraying were conducted in Iquitos, Peru. In each, a central sprayed sector was surrounded by an unsprayed buffer sector. In 2013, spray and buffer sectors included 398 and 765 houses, respectively. Spraying reduced the mean number of adults captured per house by ~83 percent relative to the pre-spray baseline survey. In the 2014 experiment, sprayed and buffer sectors included 1,117 and 1,049 houses, respectively. Here, the sprayed sector's number of adults per house was reduced ~64 percent relative to baseline. Parity surveys in the sprayed sector during the 2014 spray period indicated an increase in the proportion of very young females. We also evaluated impacts of a 2014 citywide spray program by the local Ministry of Health, which reduced adult populations by ~60 percent. In all cases, adult densities returned to near-baseline levels within one month. Conclusions/Significance: Our results demonstrate that densities of adult Ae. aegypti can be reduced by experimental and municipal spraying programs. The finding that adult densities return to approximately pre-spray densities in less than a month is similar to results from previous, smaller scale experiments. Our results demonstrate that ULV spraying is best viewed as having a short-term entomological effect. The epidemiological impact of ULV spraying will need evaluation in future trials that measure capacity of insecticide spraying to reduce human infection or disease

Efficacy of <i>Aedes aegypti</i> control by indoor Ultra Low Volume (ULV) insecticide spraying in Iquitos, Peru

<div><p>Background</p><p><i>Aedes aegypti</i> is a primary vector of dengue, chikungunya, Zika, and urban yellow fever viruses. Indoor, ultra low volume (ULV) space spraying with pyrethroid insecticides is the main approach used for <i>Ae</i>. <i>aegypti</i> emergency control in many countries. Given the widespread use of this method, the lack of large-scale experiments or detailed evaluations of municipal spray programs is problematic.</p><p>Methodology/Principal findings</p><p>Two experimental evaluations of non-residual, indoor ULV pyrethroid spraying were conducted in Iquitos, Peru. In each, a central sprayed sector was surrounded by an unsprayed buffer sector. In 2013, spray and buffer sectors included 398 and 765 houses, respectively. Spraying reduced the mean number of adults captured per house by ~83 percent relative to the pre-spray baseline survey. In the 2014 experiment, sprayed and buffer sectors included 1,117 and 1,049 houses, respectively. Here, the sprayed sector’s number of adults per house was reduced ~64 percent relative to baseline. Parity surveys in the sprayed sector during the 2014 spray period indicated an increase in the proportion of very young females. We also evaluated impacts of a 2014 citywide spray program by the local Ministry of Health, which reduced adult populations by ~60 percent. In all cases, adult densities returned to near-baseline levels within one month.</p><p>Conclusions/Significance</p><p>Our results demonstrate that densities of adult <i>Ae</i>. <i>aegypti</i> can be reduced by experimental and municipal spraying programs. The finding that adult densities return to approximately pre-spray densities in less than a month is similar to results from previous, smaller scale experiments. Our results demonstrate that ULV spraying is best viewed as having a short-term entomological effect. The epidemiological impact of ULV spraying will need evaluation in future trials that measure capacity of insecticide spraying to reduce human infection or disease.</p></div

Model estimates of <i>Ae</i>. <i>aegypti</i> adults per house (AA/HSE, top row) and proportion infested houses (PrIH = AHI).

<p>A separate generalized linear model (GLM) was constructed for each experiment (column) and for each measured response (row). (A) AA/HSE, negative binomial GLM (NB-GLM). (B) PrIH, logistic GLM (L-GLM). Models describe response of measure (row) to time period (X-axis) and treatment sector (color & shape). Shading indicates spray events: experimental spraying (light) and citywide spraying (dark). Vertical bars show 95% CI; non-overlapping CI indicate highly significant difference. Letters (s, t) indicate significant differences between pairwise contrasts: s, between sector (within time, <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0006378#pntd.0006378.s011" target="_blank">S2 Table</a>); t, between time (within spray sector, relative to baseline C1, <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0006378#pntd.0006378.s012" target="_blank">S3 Table</a>). See also <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0006378#pntd.0006378.s015" target="_blank">S6A and S6B Table</a>, <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0006378#pntd.0006378.s016" target="_blank">S7A and S7B Table</a>, and <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0006378#pntd.0006378.s006" target="_blank">S5 Fig</a>.</p

Detailed time series of AA/HSE response to ULV spraying, aggregated by week.

<p>X-axis shows week start date. Color and symbol shape shows sector (orange triangle: spray sector). Point size shows number of surveyed houses. Vertical dashed lines show approximate dates of experimental spraying (spray sector only). Vertical colored bars show bootstrap 95% CI (1e+04 draws per circuit).</p

Generalized linear mixed model (L-GLMM) results: <i>Ae</i>. <i>aegypti</i> control cage mortality and knockdown.

<p>Generalized linear mixed model (L-GLMM) results: <i>Ae</i>. <i>aegypti</i> control cage mortality and knockdown.</p

Summary of <i>Aedes aegypti</i> collected in 2013 and 2014 experiments evaluating ultra-low-volume space sprays in Iquitos, Peru.

<p>Observation counts include houses, surveys^{<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0006378#t001fn001" target="_blank">*</a>}, sampled adult mosquitoes, sampled containers, and adult female dissections^{<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0006378#t001fn002" target="_blank">**</a>} (parity).</p

Sampling and spraying.

<p>(A) Number of houses per week sprayed and/or surveyed. Circuits are labeled (e.g., C1), with date ranges shown by horizontal bars. Containers were not surveyed during spray periods. The first two emergency (citywide) spray events (red +) occurred within the same calendar week, but are plotted separately here. (B) Spray coverage by spray cycle. Percent houses sprayed is shown in text. Top row: emergency (citywide) spraying. Bottom row: experimental spraying.</p