Gary N. Fritz

Selective Male Mortality in the Red Imported Fire Ant, Solenopsis invicta

Males in polygyne populations of Solenopsis invicta are primarily sterile diploids and thought to not express the Gp-9 gene coding for a pheromone-binding protein affecting complex social behavior. We examined an aspect of the breeding system hitherto not considered—male Gp-9 genotypes in relation to sperm stored in queens. Four sites with varying frequencies of sympatric monogyne and polygyne colonies were sampled, including sexuals, workers, and broods from four colonies. Most queens were heterozygotes storing B sperm. Although predicted to be common, only 14 of 504 males were B or BB genotypes, suggesting strong selection. Increased frequency of polygyne colonies at each site paralleled increases in queens with b sperm (1.9–32.8%) and of noninseminated queens. The presence of both B and b sperm in 1.9–18.9% of queens, genotype profiles of colonies, and genotypes of offspring from individual queens suggest some frequency of multiple mating. The bb genotype, rather than an obligate, developmental lethal, was present in some queens and common in alates, workers, and brood. Selective mortality of sexuals may affect multiple aspects of the breeding system, including female-mediated dispersal, mating success, and gene flow.

Sympatry of Polygyne and Monogyne Colonies of the Fire Ant Solenopsis invicta (Hymenoptera: Formicidae)

Abstract The polygyne form of the red imported fire ant, Solenopsis invicta Buren, is thought to occur primarily in discrete populations embedded within areas composed of monogyne colonies. This distribution implies that polygyne colonies compete with monogyne colonies and subsequently create a population homogenous in social form. Because polygyne colonies produce mostly sterile males, opportunities for insemination of female alates might be minimal at the centers of large polygyne areas. To test for homogeneity in social form, a large polygyne population described in northcentral Florida was examined for the presence of single queen colonies. Forty-six to 51 colonies were sampled from each of six sites located along an east-west transect through the middle of the polygyne area in Marion County and a site at the northernmost limit of the polygyne area, Gainesville, FL. Several hundred workers from each nest were collected along with nest material. The social form of each sample was determined by an aggression test of workers to the introduction of non-nestmates and by the dissection of males for sterility. Both social forms of S. invicta were present at all collection sites and 103 of 333 (30.93%) colonies sampled were determined to be monogyne colonies. Among the collection sites, the percentage of colonies that were monogyne ranged from 3.9 to 57.4%. The polygyne region in northcentral Florida is more accurately described as an area where relatively high frequencies of polygyne colonies are interdispersed with single queen colonies.

Phylogeography of the neotropical Anopheles triannulatus complex (Diptera: Culicidae) supports deep structure and complex patterns

BackgroundThe molecular phylogenetic relationships and population structure of the species of the Anopheles triannulatus complex: Anopheles triannulatus s.s., Anopheles halophylus and the putative species Anopheles triannulatus C were investigated.MethodsThe mitochondrial COI gene, the nuclear white gene and rDNA ITS2 of samples that include the known geographic distribution of these taxa were analyzed. Phylogenetic analyses were performed using Bayesian inference, Maximum parsimony and Maximum likelihood approaches.ResultsEach data set analyzed septely yielded a different topology but none provided evidence for the seption of An. halophylus and An. triannulatus C, consistent with the hypothesis that the two are undergoing incipient speciation. The phylogenetic analyses of the white gene found three main clades, whereas the statistical parsimony network detected only a single metapopulation of Anopheles triannulatus s.l. Seven COI lineages were detected by phylogenetic and network analysis. In contrast, the network, but not the phylogenetic analyses, strongly supported three ITS2 groups. Combined data analyses provided the best resolution of the trees, with two major clades, Amazonian (clade I) and trans-Andean + Amazon Delta (clade II). Clade I consists of multiple subclades: An. halophylus + An. triannulatus C; trans-Andean Venezuela; central Amazonia + central Bolivia; Atlantic coastal lowland; and Amazon delta. Clade II includes three subclades: Panama; cis-Andean Colombia; and cis-Venezuela. The Amazon delta specimens are in both clades, likely indicating local sympatry. Spatial and molecular variance analyses detected nine groups, corroborating some of subclades obtained in the combined data analysis.ConclusionCombination of the three molecular markers provided the best resolution for differentiation within An. triannulatus s.s. and An. halophylus and C. The latest two species seem to be very closely related and the analyses performed were not conclusive regarding species differentiation. Further studies including new molecular markers would be desirable to solve this species status question. Besides, results of the study indicate a trans-Andean origin for An. triannulatus s.l. The potential implications for malaria epidemiology remain to be investigated.

Isolating, Amplifying and Quantifying Sperm DNA in Anastrepha suspensa (Diptera: Tephritidae)

ABSTRACT A major obstacle for many studies examining sperm competition and cryptic female choice in insects has been the identification and quantification of sperm stored in the sperm storage organs of females that have mated with two or more males. Historically, sexual selection studies have focused primarily on paternity outcomes for inferring potential underlying mechanisms (e.g., sperm competition and cryptic female choice). We describe a technique for isolating, genotyping and quantifying sperm in Anastrepha suspensa Loew, a species that has four sperm storage organs (three spermathecae and a ventral receptacle) that are minute (approximately 80 µm) and exhibit complex interior structures restricting sperm recovery through simple dissection. With our protocol, we were able to isolate and amplify sperm DNA (PCR of microsatellite loci) without contamination from female cells, and quantify sperm contributed to a storage organ by one or more males. Briefly, sperm storage organs are dissected-out of the female abdomen, sonicated to remove female cells, rinsed in saline, crushed between micro-slides (1 × 2 mm), and placed in a microcentrifuge tube for DNA isolation in situ using a solution containing 10% chelex, proteinase-K and DTT. After boiling, the DNA is amplified by PCR. With this technique, we have successfully amplified microsatellite loci from as few as 10 ± 3 sperm. Estimates of absolute numbers of sperm stored in sperm storage organs was accomplished by incorporating a reference amplicon standard in each sample during fragment analysis of microsatellite loci. The protocol described in this study enable the localization, identification and quantification of sperm from multiple males stored in female sperm storage organs and, therefore, generates data that can augment interpretations of paternity outcomes. Translation provided by the authors.

Sequence Analysis of the rDNA Internal Transcribed Spacer 2 and Polymerase Chain Reaction Identification of Anopheles fluminensis (Diptera: Culicidae: Anopheles) in Bolivia

Abstract Anopheles fluminensis Root is a member of the Arribalzagia Series in the subgenus Anopheles. We report the first record of this species in the department of Cochabamba, Bolivia. This species was sampled from two locations in the foothills of the eastern Andes Mountains within the Chapare Valley. Larvae were collected in fast-flowing, shaded streams at the edges of rocky pools. We provide the first sequence data for the rDNA of An. fluminensis, a partial sequence of the 5.8S and the internal transcribed spacer 2 (ITS2). The ITS2 of An. fluminensis, sequenced from two individuals at one site, was at least 596 bp, had 56.5% GC, and included three large repeats (≈125 bp each). We describe a polymerase chain reaction protocol and species-specific primers for identifying this species in the Chapare Valley, Bolivia.

Identification of Anopheles (Nyssorhynchus) marajoara (Diptera: Culicidae) in Bolivia Using Polymerase Chain Reaction and a Restriction Endonuclease

Abstract Anopheles (Nyssorhynchus) marajoara Galvão & Damasceno (Diptera: Culicidae) is a member of the Albitarsis cryptic species complex and is a primary vector of human Plasmodium in parts of Brazil. We report the first record of An. marajoara in the department of Cochabamba and confirm its presence in the department of Santa Cruz, Bolivia. We also describe a PCR protocol producing a single amplicon (≈340 bp) of a section of the internal transcribed spacer 2 specific for members of the Albitarsis species complex; the polymerase chain reaction protocol did not amplify the DNA of 17 other species in the subgenus Nyssorhynchus. Digestion of the amplicon with the restriction endonuclease BfaI produces two fragments specific to An. marajoara in Bolivia.

Morphometric Variability of Anopheles pseudopunctipennis (Diptera: Culicidae) from Different Ecoregions of Argentina and Bolivia

ABSTRACT Anopheles pseudopunctipennis is a New World species extending from about 30°S in central Argentina to about 40°N in the USA. It is considered one of the most important malaria vectors in South America and its implication in malaria transmission varies along its distribution. We evaluated the effect of ecoregion and geographical distances on the traits or morphological characters of An. pseudopunctipennis females from 15 localities in Argentina and Bolivia using cladistic and morphometric analyses. The cladistic analysis (Maximum Parsimony) demonstrated that the effect of ecoregion characterization in distinguishing between Bolivian and Argentinean populations was stronger than the effect of geographical distances. Morphometric analysis (Discriminant analysis) did not reveal a pattern between Bolivian and Argentinean populations based on geographical distances. Ecoregional characterization of An. pseudopunctipennis populations throughout is range, caused us to conclude that studies of morphological traits characteristics are necessary in differentiating between populations. Moreover, molecular studies are required to determine whether geographical distances influence population differentiation in An. pseudopunctipennis from Argentina and Bolivia, in the extreme south of South America.

Zygoribatula Floridana N. Sp. (Acari: Oribatulidae), with a List of Species in the Genus

A description is given of the oribatid mite Zygoribatula floridana n. sp. collected from goat pastures in northcentral Florida. This species carries Moniezia expansa (Rudolphi) (Cestoda: Anoplocephalidae) cysticercoids. A list is given of all species currently classified in Zygoribatula Berlese along with holotype habitat and locality.

Reproductive Partitioning in Vespula squamosa (Hymenoptera: Vespidae)

Abstract The yellowjacket, Vespula squamosa (Drury) (Hymenoptera: Vespidae), is the only eusocial wasp that commonly has 2 social forms (monogyne and polygyne nests), has annual and perennial nests, facultatively usurps the nests of conspecifics, and parasitizes other vespine species. Thus, V. squamosa is ideally suited for examining various phenotypic and genetic variables as they relate to different social alternatives in the context of kin selection theory. In this study, we compared various metrics relating to reproduction for queens in monogyne versus polygyne nests including queen abdominal weight, fertility, egg number, egg size, and worker relatedness. Monogyne nests (N = 7) and polygyne nests (N = 5) were collected from Georgia and Florida, USA. Examination of nest comb material indicated all polygyne nests were perennial; the number of workers in these nests varied from approximately 700 to 36,379. All monogyne nests were annual and had fewer than 1,500 workers. Single queens were more physogastric than their polygyne counterparts and had significantly more mature eggs per ovary. Polygyne queens, however, had significantly larger eggs but produced smaller workers. Twelve percent of the queens in polygyne nests were either devoid of sperm or did not have full spermathecae (n = 142), whereas the spermathecae of single queens (n = 7) were replete with spermatozoa. Mean genetic relatedness among workers in perennial, polygyne nests suggests these nests include multiple egg-laying queens.

Sampling High-Altitude and Stratified Mating Flights of Red Imported Fire Ant

ABSTRACT With the exception of an airplane equipped with nets, no method has been developed that successfully samples red imported fire ant, Solenopsis invicta Buren, sexuals in mating/dispersal flights throughout their potential altitudinal trajectories. We developed and tested a method for sampling queens and males during mating flights at altitudinal intervals reaching as high as ∼140 m. Our trapping system uses an electric winch and a 1.2-m spindle bolted to a swiveling platform. The winch dispenses up to 183 m of Kevlar-core, nylon rope and the spindle stores 10 panels (0.9 by 4.6 m each) of nylon tulle impregnated with Tangle-Trap. The panels can be attached to the rope at various intervals and hoisted into the air by using a 3-m-diameter, helium-filled balloon. Raising or lowering all 10 panels takes ∼15–20 min. This trap also should be useful for altitudinal sampling of other insects of medical importance.