Description of a method for localizing swarming mosquitoes and other insects in 3D space with visualizations

Male mosquitoes swarm to find mates, but the characteristics of these swarms have not yet been quantitatively analyzed in the field. This paper describes a simple method used recently to localize individual Anopheles gambiae in a swarm via stereoscopic image analysis of video footage swarms recorded in Doneguebougou, Mali. The methods described here represent a streamlining of simple triangulation for insect localization in the hope that other researchers will be able to apply the method for studying fundamental questions about flying insects or other taxa.
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Response of a Pearly Eye Melon Fly Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae) Mutant to Host-Associated Visual Cues

We report on a pearly eye mutant (PEM) line generated from a single male of Bactrocera cucurbitae collected in Kapoho, Hawaii. Crossing experi- ments with colony wild-type flies indicate that the locus controlling this trait is autosomal and the mutant allele is recessive. Experiments with females to assess response to visual oviposition cues (shape and color) suggest that PEM flies are at least unresponsive to color, and likely also unable to perceive visual shape cues. This phenotype has been described from field collection before, but its visual abili- ties have not previously been tested. The rediscovery of the PEM phenotype and results of the vision test support the hypothesis that the PEM trait has significant negative fitness consequences in the field, and that the recessive allele resulting in this phenotype probably occurs at a low frequency in nature

Vegetation classification of Coffea on Hawaii Island using WorldView-2 satellite imagery

Coffee is an important crop in tropical regions of the world; about 125 million people depend on coffee agriculture for their livelihoods. Understanding the spatial extent of coffee fields is useful for management and control of coffee pests such as Hypothenemus hampei and other pests that use coffee fruit as a host for immature stages such as the Mediterranean fruit fly, for economic planning, and for following changes in coffee agroecosystems over time. We present two methods for detecting Coffea arabica fields using remote sensing and geospatial technologies on WorldView-2 high-resolution spectral data of the Kona region of Hawaii Island. The first method, a pixel-based method using a maximum likelihood algorithm, attained 72% producer accuracy and 69% user accuracy (68% overall accuracy) based on analysis of 104 ground truth testing polygons. The second method, an object-based image analysis (OBIA) method, considered both spectral and textural information and improved accuracy, resulting in 76% producer accuracy and 94% user accuracy (81% overall accuracy) for the same testing areas. We conclude that the OBIA method is useful for detecting coffee fields grown in the open and use it to estimate the distribution of about 1050 hectares under coffee agriculture in the Kona region in 2012

An Optimized Protocol for Rearing Fopius arisanus, a Parasitoid of Tephritid Fruit Flies

Fopius arisanus (Sonan) is an important parasitoid of Tephritid fruit flies for at least two reasons. First, it is the one of only three opiine parasitoids known to infect the host during the egg stage1. Second, it has a wide range of potential fruit fly hosts. Perhaps due to its life history, F. arisanus has been a successfully used for biological control of fruit flies in multiple tropical regions2-4. One impediment to the wide use of F. arisanus for fruit fly control is that it is difficult to establish a stable laboratory colony5-9. Despite this difficulty, in the 1990s USDA researchers developed a reliable method to maintain laboratory populations of F. arisanus10-12. There is significant interest in F. arisanus biology13,14, especially regarding its ability to colonize a wide variety of Tephritid hosts14-17; interest is especially driven by the alarming spread of Bactrocera fruit fly pests to new continents in the last decade18. Further research on F. arisanus and additional deployments of this species as a biological control agent will benefit from optimizations and improvements of rearing methods. In this protocol and associated video article we describe an optimized method for rearing F. arisanus based on a previously described approach12. The method we describe here allows rearing of F. arisanus in a small scale without the use of fruit, using materials available in tropical regions around the world and with relatively low manual labor requirements

Mark-Release-Recapture Experiments on the Effectiveness of Methyl Eugenol–Spinosad Male Annihilation Technique Against an Invading Population of Bactrocera dorsalis

Bactrocera dorsalis is a pest of major concern in fruit-growing areas where it is not established. Control and eradication often employs male annihila- tion technique, using methyl eugenol as an attractant (MAT-ME). We conduced a small-scale mark-release-recapture study comparing two densities of MAT-ME (“high” = 225 spots per km2; “low” = 100 spots per km2) with a control by counting males recaptured in sentinel traps baited with ME 40 m from the release point. We hypothesized that recaptures would be reduced under the two MAT treatments by equivalent amounts compared with the control, reflecting male mortality from the treatments. We found a large degree of variation in trap recaptures between replicates and treatments, and no significant difference between recaptures under the high treatment and control. Recaptures were significantly lower under the low treatment, indicating greater mortality compared with control and high. We propose the “MAT-ME saturation hypothesis” to explain this result: increasing the number of stations per square mile increases mortality of receptive males until too many stations create a high enough background of ME that the males don’t effectively follow a gradient to MAT sources. Our findings highlight that further research into the effect of increasing MAT-ME spot density on male mortality is needed

Spatial swarm segregation and reproductive isolation between the molecular forms of Anopheles gambiae

Anopheles gambiae, the major malaria vector in Africa, can be divided into two subgroups based on genetic and ecological criteria. These two subgroups, termed the M and S molecular forms, are believed to be incipient species. Although they display differences in the ecological niches they occupy in the field, they are often sympatric and readily hybridize in the laboratory to produce viable and fertile offspring. Evidence for assortative mating in the field was recently reported, but the underlying mechanisms awaited discovery. We studied swarming behaviour of the molecular forms and investigated the role of swarm segregation in mediating assortative mating. Molecular identification of 1145 males collected from 68 swarms in Donéguébougou, Mali, over 2 years revealed a strict pattern of spatial segregation, resulting in almost exclusively monotypic swarms with respect to molecular form. We found evidence of clustering of swarms composed of individuals of a single molecular form within the village. Tethered M and S females were introduced into natural swarms of the M form to verify the existence of possible mate recognition operating within-swarm. Both M and S females were inseminated regardless of their form under these conditions, suggesting no within-mate recognition. We argue that our results provide evidence that swarm spatial segregation strongly contributes to reproductive isolation between the molecular forms in Mali. However this does not exclude the possibility of additional mate recognition operating across the range distribution of the forms. We discuss the importance of spatial segregation in the context of possible geographic variation in mechanisms of reproductive isolation

Population Size and Migration of Anopheles gambiae in the Bancoumana Region of Mali and Their Significance for Efficient Vector Control

We present results of two intensive mark-release-recapture surveys conducted during the wet and dry seasons of 2008 in the villages of Fourda and Kenieroba, Mali. The former is a small fishing village by the Niger River with a moderate to high densities of Anopheles gambiae Giles s.s. (Diptera: Culicidae) throughout the year, while the latter is a large agricultural community 2 km inland that experiences strong seasonal fluctuation in An. gambiae densities. We estimate the population size of female An. gambiae in Fourda to be in less than 3,000 during the dry season. We found evidence of large population size and migration from Fourda in Kenieroba during the wet season, but very low numbers and no sign of migrants during the dry season. We suggest that malaria vector control measures aimed at adult mosquitoes might be made more efficient in this region and other seasonal riparian habitats by targeting disruption of mosquito populations by the river during the dry season. This would decrease the size of an already small population, and would be likely to delay the explosive growth in vector numbers in the larger inland villages as rainfall increases

Seasonal Climate Effects Anemotaxis in Newly Emerged Adult Anopheles gambiae Giles in Mali, West Africa

The direction and magnitude of movement by the malaria vector Anopheles gambiae Giles has been of great interest to medical entomologists for over 70 years. This direction of movement is likely to be affected by many factors, from environmental conditions and stage of life history of the mosquito to the existence of attractants in the vicinity. We report here the direction of movement of newly emerged An. gambiae in nature, around the village of Donéguébougou, Mali. We assessed the direction of movement for individual mosquitoes by placing them in a novel enclosure with exit traps oriented in the direction of the cardinal and intermediate points of the compass. We consistently found predominantly Southward directions of movement during 2009 and 2010, with an additional Eastward component during the dry season and a Westward one during the wet season. Our data indicate that wind has an important effect on the direction of movement, but that this effect varied by season: Average directions of movement were downwind during the dry season and upwind during the wet season. A switch in anemotactic response suggests that the direction of movement of An. gambiae relative to the wind immediately after emergence under varying conditions of humidity should be further investigated under controlled conditions