Phorid Species Research Articles

Scuttle fly Megaselia scalaris (Loew) (Diptera: Phoridae) endoparasitoid as a novel biocontrol agent against adult American cockroaches (Periplaneta americana)

The American cockroach, Periplaneta americana (Linnaeus, 1758) (Blattodea: Blattidae), is one of the most common pests that thrive in diverse environments and carries various pathogens, causing critical threats to public health and the ecosystem. We thus report in this study the first observation of decapitated American cockroaches as a result of infestation with scuttle fly parasitoids. Interestingly, behavioral alterations in the form of zombification-like behavior could be observed in cockroaches reared in the laboratory before being decapitated, implying that the insect targets cockroach heads. To identify this parasitoid, cockroaches’ corpora were isolated in jars, and apodous larvae were observed. Larvae developed into small coarctate pupae, and adults emerged. The scuttle flies were collected and exhibited tiny black, brown, to yellowish bodies. The fly was initially identified based on its morphological properties as a member of the order Diptera, family Phoridae. To provide further insights into the morphological attributes of the phorid species, the fly was examined using a scanning electron microscope (SEM) and then identified as Megaselia scalaris accordingly. SEM analysis revealed the distinctive structure of M. scalaris concerning the head, mouth parts, and legs. Specifically, the mouth parts include the labrum, labellum, rostrum, and maxillary palps. Although further investigations are still required to understand the complicated relationships between M. scalaris and American cockroaches, our findings provide a prominent step in the control of American cockroaches using M. scalaris as an efficient biological control agent.

The first records of eleven species of the genus Megaselia Rondani, 1856 from Morocco (Diptera, Phoridae)

We provide new records of scuttle flies, family Phoridae (Diptera), from Morocco, which has been very little studied. Eleven phorid species belonging to the immense genus Megaselia Rondani, 1856 are newly reported from the country, increasing the number of known species in Morocco to 12, and the number of Phoridae to 14. Information on the distribution and ecology of each species is provided.

Phorid fly parasitism rates vary between individual colonies of the leaf‐cutting ant Atta laevigata

Abstract Phorid flies are important natural enemies of leaf‐cutting ants. Female phorids lay eggs in the worker ants' bodies and the parasitoid larvae feed on the host's internal tissues. Here we investigated the parasitism rates by four species of phorids when attacking individual Atta laevigata colonies at three different field sites in order to further understand the host‐parasitoid relationship. There were distinct variations in parasitism rates when comparing phorid species attacking individual colonies. In 13 of the colonies sampled, parasitism by Apocephalus attophilus or Eibesfeldtphora erthali was predominant. However, in four of the colonies, Myrmosicarius grandicornis and Apocephalus vicosae were the predominant species. Variations in parasitism rates by the four phorid species were investigated in relation to the size of the potential hosts that had been collected from the foraging trails of each colony. When correlating the size of potential hosts to phorid species, ants with head capsule widths of >2 mm were predominantly parasitized by A. vicosae and E. erthali. Smaller ants, with head capsule widths of 2 mm or less, were predominantly parasitized by A. attophilus and M. grandicornis. The highest parasitism rates by E. erthali were observed in individual colonies that had the highest proportions of large workers on the trails. Although almost half the size of E. erthali, A. attophilus parasitized both large (head capsule width > 2 mm) and small workers (<2 mm). This was related to the fact that between 1 and 16 larvae can develop within an individual host, depending on host size. M. grandicornis parasitized smaller workers (mean head capsule width = 2 mm) as these phorids are themselves small and only one larva develops within each host. This study demonstrated that the parasitism profiles of individual A. laevigata colonies were related to the size of foragers on the trails.

Phorid parasitoids of the leaf‐cutting ant Atta laevigata in the Atlantic Forest: occurrence, parasitism rate, and host size

AbstractThe leaf‐cutting ant Atta laevigata (Smith) (Hymenoptera: Formicidae, Attini) causes significant damage to agricultural crops and forest plantations. Conventional control strategies include the use of formicide bait, whose active ingredients pose environmental risks. Several flies of the family Phoridae (Diptera) have shown potential as biocontrol agents of leaf‐cutting ants. This study aimed to determine which phorid species parasitise A. laevigata in the Atlantic Forest, their parasitism rates, and host sizes. Phorids and ants were collected during 12 months from foraging trails and entrance holes of A. laevigata nests located in a natural forest of southeastern Brazil. Phorids collected in the field and those emerged from parasitised ants were identified at the species level. Parasitism rate was determined for each phorid species, the head width of parasitised ants was measured, and confidence intervals were calculated. Eibesfeldtphora erthali (Brown), Eibesfeldtphora bragancai (Brown), Eibesfeldtphora declinata (Bogmeier), Apocephalus vicosae Disney, Apocephalus attophilus Borgmeier, and Myrmosicarius grandicornis Borgmeier parasitised A. laevigata at an overall rate of (mean ± SE =) 5.9 ± 0.76%. Apocephalus spp. had the highest parasitism rate (2.8 ± 0.60%), followed by Eibesfeldtphora spp. (2.2 ± 0.77%), A. vicosae (0.23 ± 0.07%), and M. grandicornis (0.16 ± 0.12%). Large workers were mainly parasitised by E. erthali and A. attophilus, intermediate workers by A. vicosae and E. declinata, and small workers by E. bragancai and M. grandicornis. The phorid A. attophilus had the highest parasitism rate, the widest range of host sizes, and an even distribution of parasitism throughout the year. The high parasitism rates registered for some nests samples (>40%) highlights that ant parasitoid flies are important natural enemies in natural environments and that they possess a great potential to be used in biocontrol programmes.

Characterization and Phylogenetic Analysis of the Complete Mitochondrial Genomes of Two Tiny Necrophagous Phorid Flies, Metopina sagittata and Puliciphora borinquenensis (Diptera: Phoridae).

The mitochondrial genome is frequently used for species identification and phylogenetic studies. In this study, we first sequenced and annotated the complete mitochondrial genomes of two phorid species that are forensically important in buried or enclosed environments: Metopina sagittata (Liu) and Puliciphora borinquenensis (Wheeler). The complete mitochondrial genome sequences of M. sagittata and P. borinquenensis were 15,640 bp with an A+T content of 75.97% and 15,429 bp with an A+T content of 75.38%, respectively. Their circular genomes both contained 13 protein-coding genes (PCGs), 22 transfer RNA genes, 2 ribosomal RNA genes, and 1 control region located between rrnS and trnI which was 808 bp for M. sagittata and 746 bp for P. borinquenensis. All the PCGs of both species started with ATN codons except for cox1 which used TTG codon. In addition to the common stop codon TAA and TAG, the incomplete stop codon T was used in two PCGs (cox1 and nad4) of M. sagittata and five PCGs (cox1, cox2, cox3, nad5, and nad4) of P. borinquenensis. There were 3 and 10 mismatched base pairs in the tRNA secondary structures from M. sagittata and P. borinquenensis, respectively. Both maximum likelihood and Bayesian inference analyses indicated that Platypezidae and Phoridae are sister taxa. M. sagittata is closely related to P. borinquenensis within the subfamily Metopininae. This work enhances the databases of Phoridae genomes and contributes to the further study of species identification and phylogenetics of this family.

Differential parasitism by four species of phorid flies when attacking three worker castes of the leaf-cutting ant Atta laevigata (Smith, 1858).

Certain species of parasitic flies belonging to the Phoridae are known to attack Atta spp. workers foraging along trails, near nest openings used by the ants to supply the colony with plant material, and in the areas where the ants are actively cutting plant material. However, there have been no previous studies of phorid parasitism of non-foraging worker ants, for example excavators and soldiers. Excavators can be found on the surface around specialized nest openings, carrying and dumping soil on characteristic mounds. Soldiers can be found on the trails protecting foragers or guarding the different types of nest openings. The current study was performed to investigate the differential parasitism rates of Atta laevigata (Smith, 1858) worker castes by four species of phorids. Ants of all castes on trails and at nest entrances were collect from 18 mature colonies in the field. A total of 21,254 ants were collected from trails and 14,649 collected from the mounds of loose soil near nest openings. The captured workers were maintained under controlled laboratory conditions to evaluate the rate of parasitism. Of the ants collected from trails, 1,112 (5.23%) were found to have been parasitized, of which 1,102 were foragers and only 10 were soldiers. Of the ants collected from the soil mounds near the nest openings, only 27 (0.18%) were found to have been parasitized, of those 25 were excavators and 2 were soldiers. When evaluating parasitism of ants on the trails, 46.2% were attacked by Apocephalus attophilus Borgmeier, 1928, 22.6% by Myrmosicarius grandicornis Borgmeier, 1928, 16.6% by Eibesfeldtphora erthali (Brown, 2001) and 14.6% by Apocephalus vicosae Disney, 2000. Only two species of phorid, M. grandicornis and E. erthali, were observed parasitizing excavators, whilst only E. erthali parasitized soldiers. This is the first time that Atta spp. excavators and soldiers have been shown to be parasitized by phorids. The low rates of parasitism and specificity of certain phorid species for excavators and soldiers is discussed in relation to the behavioral interactions of hosts and their parasitoids, as well as the relationship between host and parasitoid size.

Parasitism of the leaf‐cutting ant Atta bisphaerica by phorid flies: biology and seasonal and inter‐colonial parasitism rates

AbstractThe leaf‐cutting ant Atta bisphaerica Forel (Hymenoptera: Formicidae, Attini) forages leaves from monocotyledons in natural environments and is a serious pest of pastures and sugarcane plantations in Brazil. This study investigated aspects of the interactions between A. bisphaerica and dipteran Phoridae parasitoids. The seasonal and inter‐colonial variations in parasitism rates were also investigated. Ants from four A. bisphaerica colonies were sampled, with a total of 91 554 worker ants collected and evaluated. Of these ants, 4.4% were found to have been parasitized by three phorid species: Apocephalus attophilus Borgmeier (relative parasitism rate: 40%), Myrmosicarius grandicornis Borgmeier (31%), and Eibesfeldtphora bragancai (Brown) (28%). The months with the lowest average temperatures, lowest relative humidity, and lowest rainfall (characteristics of the dry season of the region under study) corresponded to the highest parasitism rates, especially by A. attophilus. Apocephalus attophilus and E. bragancai had the highest relative parasitism rates in two of the colonies, 45 and 41%, whereas M. grandicornis was the dominant species in each of the other two colonies, corresponding to approximately 40% of total parasitism. The variation in parasitism rates observed between colonies could be explained, at least in part, by the relationship between the size of the parasitoids and the size of the host ants. Concerning the biological characteristics, A. attophilus had the shortest life cycle, the highest successful emergence rate, and produced 2.5× more parasitoids per host. These characteristics, combined with the ability to cause higher levels of mortality of parasitized worker ants when compared to the two other phorid species, indicates that A. attophilus is an efficient natural enemy of A. bisphaerica and is therefore a candidate for a biocontrol program.

Rapid, large-scale species discovery in hyperdiverse taxa using 1D MinION sequencing

BackgroundMore than 80% of all animal species remain unknown to science. Most of these species live in the tropics and belong to animal taxa that combine small body size with high specimen abundance and large species richness. For such clades, using morphology for species discovery is slow because large numbers of specimens must be sorted based on detailed microscopic investigations. Fortunately, species discovery could be greatly accelerated if DNA sequences could be used for sorting specimens to species. Morphological verification of such “molecular operational taxonomic units” (mOTUs) could then be based on dissection of a small subset of specimens. However, this approach requires cost-effective and low-tech DNA barcoding techniques because well-equipped, well-funded molecular laboratories are not readily available in many biodiverse countries.ResultsWe here document how MinION sequencing can be used for large-scale species discovery in a specimen- and species-rich taxon like the hyperdiverse fly family Phoridae (Diptera). We sequenced 7059 specimens collected in a single Malaise trap in Kibale National Park, Uganda, over the short period of 8 weeks. We discovered > 650 species which exceeds the number of phorid species currently described for the entire Afrotropical region. The barcodes were obtained using an improved low-cost MinION pipeline that increased the barcoding capacity sevenfold from 500 to 3500 barcodes per flowcell. This was achieved by adopting 1D sequencing, resequencing weak amplicons on a used flowcell, and improving demultiplexing. Comparison with Illumina data revealed that the MinION barcodes were very accurate (99.99% accuracy, 0.46% Ns) and thus yielded very similar species units (match ratio 0.991). Morphological examination of 100 mOTUs also confirmed good congruence with morphology (93% of mOTUs; > 99% of specimens) and revealed that 90% of the putative species belong to the neglected, megadiverse genus Megaselia. We demonstrate for one Megaselia species how the molecular data can guide the description of a new species (Megaselia sepsioides sp. nov.).ConclusionsWe document that one field site in Africa can be home to an estimated 1000 species of phorids and speculate that the Afrotropical diversity could exceed 200,000 species. We furthermore conclude that low-cost MinION sequencers are very suitable for reliable, rapid, and large-scale species discovery in hyperdiverse taxa. MinION sequencing could quickly reveal the extent of the unknown diversity and is especially suitable for biodiverse countries with limited access to capital-intensive sequencing facilities.

Phorid species from Acromyrmex’s hosts and effect on their survival of two fungi proposed for the control of leafcutter ants

AbstractPhorid flies (Diptera: Phoridae, Metopinini) are natural enemies of leafcutter ants (Hymenoptera: Formicidae, Attini), which are among the most important pests in the Neotropical region. These parasitoids lay their eggs inside worker ants, causing the death of the parasitized ants, and the oviposition attacks on foraging workers interfere with the collection of vegetal material used in fungal gardens, thereby affecting the whole colony. However, because of the large number of ants per colony, more than one type of biological control agent is needed to have a significant impact. We collected parasitized leafcutter ants Acromyrmex lundii (Guérin‐Méneville), Acromyrmex heyeri (Forel), and Acromyrmex ambiguus (Emery) from various places in Argentina and reared their parasitoids. We recorded developmental times, host and phorid sizes, and other aspects of the biology of the phorids Apocephalus neivai Borgmeier, Apocephalus noetingerorum Brown & Disney, Myrmosicarius gracilipes Borgmeier, Myrmosicarius catharinensis Borgmeier, Myrmosicarius crudelis Borgmeier, and Myrmosicarius cristobalensis Disney et al. This is the first record of A. ambiguus, an important pest of pine plantations, being a host of phorids. We found the first cases of gregarious parasitoidism of a parasitoid with no‐free pupae: M. catharinensis on A. lundii ants. We also evaluated the effect on pupal survival of two cosmopolitan fungi, Beauveria bassiana (Balsamo) Vuill. and Trichoderma lentiforme (Rehm) Chaverri et al., which are also considered as potential biological control agents of leafcutter ants. Suspensions of conidia were tested on Myrmosicarius and Apocephalus parasitoid pupae of different ages. No negative effect on pupal survival was found under either fungal treatment. Therefore, the use of both natural enemies separately but simultaneously, or the introduction of fungi‐inoculated pupae in the pest habitats, seems to be a promising strategy for the multiple biological control of leafcutter ants.

A new species of Megaselia Rondani (Diptera: Phoridae) associated with one sex of a dioecious fig tree in Thailand

Megaselia ischnopodae Disney n. sp. (Diptera, Phoridae) is reared from larvae found in mature male figs of Ficus ischnopoda Miq. (Urticales, Moracea) in Thailand. Other phorid species associated with fig trees are briefly reviewed.

Parasitism, sexual dimorphism and effect of host size on Apocephalus attophilus offspring, a parasitoid of the leaf-cutting ant Atta bisphaerica.

Atta bisphaerica (Forel) is a leaf-cutting ant that specializes on grass and causes productivity losses in sugar cane fields and pastures. Three phorid species, Apocephalus attophilus (Borgmeier), Myrmosicarius grandicornis (Borgmeier) and Eibesfeldtphora bragancai (Brown), have been found parasitizing A. bisphaerica workers. These parasitoids can reduce plant material transported into the nests and ant traffic on the trails. Therefore, phorid flies have been considered potential biological control agents for leaf-cutting ants. Here, we evaluated which parasitoid species attack the leaf-cutting ant A. bisphaerica in pasture areas of a Brazilian Savannah-Atlantic Forest ecotone, parasitism rate, effect of host size, sexual dimorphism and sex ratio of the emerged parasitoids. Four nests of A. bisphaerica were selected in pasture areas from August 2016 to August 2017, with 400 workers collected from each colony monthly. A total of 23,714 A. bisphaerica workers were collected during the study, of which 236 (0.99%) were parasitized by phorid parasitoids. Apocephalus attophilus, E. bragancai and M. grandicornis parasitized 217, 17 and 2 ants, respectively. The higher parasitism rate was found in the hottest/rainy season of the year. Non-parasitized ants survived longer than those parasitized by A. attophilus. The larval and pupal periods of this parasitoid were 2.2 ± 0.8 and 16 ± 1.4 days, respectively, and the number of pupae per parasitized ant ranged from 1 to 7. The number of A. attophilus pupae per host increased with the host head size. Likewise, the size of the adult parasitoids also increased according to the host ant. Apocephalus attophilus females were larger than males and the sex ratio (male: female) did not differ from 1: 1. Our results showed that A. attophilus would be a potential biocontrol agent of leaf-cutting ants because it produces multiple larvae per host, allowing a great production of parasitoids with short developmental time and kills the host ant faster than other phorids.

New records and new host-parasitoid interactions of phorids (Diptera: Phoridae) parasitizing leafcutter ants (Hymenoptera: Formicidae) in Argentina

Leafcutter ants are one of the most important crop pests in the Neotropics. In the present study, several specimens were collected from four provinces in Argentina in order to determine the species of phorid flies parasitizing them. We report our findings on seven phorid species, Apocephalus neivai Borgmeier, Ap. noetingerorum Disney, Neodohrniphora unichaeta Disney, Myrmosicarius catharinensis Borgmeier, M. cristobalensis Disney, M. crudelis Borgmeier and M. gracilipes Borgmeier, over the leafcutter ants Acromyrmex ambiguus Emery, Ac. crassispinus Forel, Ac. heyeri Forel, Ac. lobicornis Emery and Ac. lundii Guérin. All the known hosts and geographic ranges for these seven phorids in Argentina are provided. The seven phorid species represent new records for all the provinces studied, expanding their geographical ranges; furthermore, we establish a total of eleven new host-parasitoid interactions. Our data expand the knowledge of this little studied system and provide important considerations for the potential use of these parasitoids as biological control candidates of the leafcutter ants

Spatial and temporal variation in host–parasitoid interactions: leafcutter ant hosts and their phorid parasitoids

1. Parasitoid–host interactions are important components of ecological communities. Although parasitoid–host interactions are strongly shaped by evolutionary history, the abundance of both the parasitoid and the host may have a role in determining the nature of the interaction once phylogenetic relationships are considered.2. Leafcutter ants are hosts of phorid parasitoids and represent a well‐defined and specialised module within a larger network of ant–symbiont interactions. A low specificity host taxa and a positive association between host abundance and parasitoid interaction frequency were expected due to the close phylogenetic relatedness of the hosts.3. The interactions among all species of leafcutter ants and their parasitoids were quantified in two localities with different species richness. This study also characterised the spatial‐temporal variability of these interactions, determined the patterns of parasitoid specificity and host selection, and tested for an association between host abundance and parasitoid interaction frequency.4. Contrary to expectation, most parasitoid species were highly specialised and interaction frequency for parasitoid species was not related to host abundance. All host ant species were attacked by more than one phorid species. Some phorid species used more than one host species and showed preference for the same species over space and time, suggesting that there are physiological and/or behavioural restrictions on host use.5. These results show that there is a tendency for specialisation even when hosts are highly similar in their ecology. From a biological control perspective, these parasitoids may be effective candidates, due to the high specificity of some species and little host‐use variation through time.

Phorid Flies Parasitizing Leaf-Cutting Ants: Their Occurrence, Parasitism Rates, Biology and the First Account of Multiparasitism

The leaf-cutting ants Atta sexdens (Linnaeus) and Atta laevigata (Smith) were parasitized by the following phorid flies: Apocephalus attophilus Borgmeier, Apocephalus vicosae Disney, Myrmosicarius grandicornis Borgmeier and species of Eibesfeldtphora Disney. It is also related here that the area of occurrence of phorids parasitizing A. sexdens was extended to include Central Brazil. The rate of parasitism on A. sexdens was three times lower than the rate found on A. laevigata; most common flies were, respectively, M. grandicornis in A. sexdens and A. attophilus in A. laevigata. This last phorid showed the shortest life span but the higher percentage of emergence. Multiparasitism on workers of A. sexdens and of A. laevigata involving three combinations of four phorid species was rare and is here related for the first time for leaf-cutting ants.

Reproductive ecology of phorid parasitoids in relation to the head size of leaf-cutting ants Atta sexdens Forel.

The leaf-cutting ant Atta sexdens Forel (Hymenoptera: Formicidae) is one of the most damaging agricultural pests in the Neotropics. Management strategies predominantly rely on the use of general insecticides. What is needed are more species-specific and environmentally friendly options. Parasitioids such as phorid flies (Diptera: Phoridae) may be one such option, but a greater understanding of the ecology of the flies and their ant hosts is essential to devise biological control strategies. Here we report parasitism rates, ant host size, parasitoid abundance per host and resultant sex ratios of two phorid species Apocephalus attophilus Borgmeier and Eibesfeldtphora tonhascai Brown parasitizing A.sexdens. The two species achieved parasitism rates of 1.48 and 1.46%, respectively and the pupal period was 14.7 ± 1.1 days and 22.1 ± 2.8 days, respectively. There was no significant difference between the head capsule width of ants parasitized by either A. attophilus or E. tonhascai. Likewise, there was no significant effect between the head capsule width of parasitized and unparasitized ants for both species. A significant positive correlation was found between the head capsule width of the parasitized ants and the number of adult parasitoids A. attophilus emerged. Ants parasitized by E. tonhascai survived significantly longer than those parasitized by A. attophilus. There was no significant effect of ant head width on the sex ratio of the offspring of either parasitoid species and no significant difference in the sex ratio (male: female) of their offspring. In summary, these data addressed here are important steps when considering natural enemies for biological control. Studying survival of the parasitized ants, parasitoid offspring sex ratio and host size preference allows for a better understanding of ant natural biological control in the field and can help in rearing of A. attophilus and E. tonhascai in laboratory.

A review of scuttle fly genera of Israel (Diptera: Phoridae), with new records and an identification key.

A brief review of Israeli scuttle flies is given. The following genera are new records for the country: Arabiphora, Billotia, Chonocephalus, Menozziola, Phalacrotophora, Pseudacteon, Psyllomyia, and Puliciphora. Eighteen species-Arabiphora tenuifemorata, Chonocephalus depressus, Conicera floricola, Conicera similis, Gymnophora integralis, Gymnophora perpropinqua, Megaselia scalaris, Megaselia stigmatica, Menozziola schmitzi, Metopina formicomendicula, Phalacrotophora beuki, Phalacrotophora fasciata, Phora limpida, Phora tincta, Psyllomyia braunsi, Puliciphora rufipes, Spiniphora bergenstammi, and Tubicera lichtwardi-are added to the list of 56 phorid species previously known from Israel. Two species, Conicera similis and Megaselia scalaris, are recorded in association with the summer truffle Tuber aestivum commercially grown in northern Israel. The status of the Afrotropical Phora congolensis Beyer, 1965 is designated as nomen dubium. A lapsius calami, which led to an erroneous generic attribution of Metopina braueri in the paper on Israeli Metopina (Mostovski, 2016), is noted here. An identification key to the Israeli genera of scuttle flies, as well as notes on recognition and/or biology of individual species, are provided.

The tip of the iceberg: a distinctive new spotted-wing Megaselia species (Diptera: Phoridae) from a tropical cloud forest survey and a new, streamlined method for Megaselia descriptions.

A new Megaselia species, M. shadeae, with a large, central, pigmented and bubble-like wing spot and a greatly enlarged radial wing vein fork, is described from Zurquí de Moravia, Costa Rica. As part of the Zurquí All Diptera Biodiversity Inventory (ZADBI) project, it represents the first of an incredible number of new phorid species to be described from this one Costa Rican cloud forest site. A new, streamlined method of description for species of this enormous genus of phorid flies is presented.

Habitat Associations of Red Imported Fire Ants (Solenopsis invicta) and Introduced Populations of Pseudacteon spp. Phorid Flies

Habitat selection is one of many aspects of red imported fire ants, Solenopsis invicta Buren, (RIFA) that has been intensively studied since their initial introduction in the United States. Concurrently, innumerable studies have attempted to identify effective chemical insecticides for RIFA control. More recently, several species of Pseudacteon spp. phorid flies (Diptera: Phoridae) have been intensively evaluated to determine their potential utility in biologica control of RIFA. These flies belong to a suite of natural enemies of RIFA in their native South American range, and have been selected for release in the United States as biological control agents against RIFA. It is hypothesized that phorid flies, through parasitism and suppression of RIFA foraging, will provide measureable RIFA population suppression as phorid ranges expand and fly densities increase. Relatively little scientific attention has been paid to habitat selection and partitioning by these flies in their introduced range(s) in the US. We assessed RIFA and phorid (Pseudacteon curvatus and Pseudacteon tricuspis) densities in four central Texas habitats. The habitat types selected represent a continuum of habitat diversity, micro-habitat availability, and plant heterogeneity. Within the habitat types studied, RIFA mound densitieswere significantly different, but foraging intensity was not significantly different in three of four habitat types. Population densities of P. curvatus were determined to be significantly higher in one habitat than all others. Alternatively, P. tricuspis densities followed a trend within the surveyed habitats that correlated with RIFA densities observed in this study. These data imply that the successful release, establishment, and range expansion of P. curvatus may require a greater degree of critical consideration regarding the ecologyof each system into which they are released, as opposed to P. tricuspis. These implications also suggest that the successful establishment of additional phorid species in the US should take into consideration the habitat matrix and habitat-based expansion corridors available to the flies.

Laboratory Rearing and Niche Resources of Pseudacteon spp. Coquillett (Diptera: Phoridae) Parasitoids of Solenopsis saevissima (Smith) (Hymenoptera: Formicidae)

Solenopsis saevissima (Smith) is associated with a group of nine Pseudacteon Coquillett species in Brazil.Pseudacteon affinis Borgmeier, Pseudacteon dentiger Borgmeier and Pseudacteon disneyi Pesquero were created in a laboratory from parasitized workers of S. saevissima. The other phorid species grew only until the pupa phase due to low temperature and humidity when kept in a climatic chamber. Pseudacteon cultellatus Borgmeier was more efficient than the other species, taking 12 days to kill the host workers. Similar to the group of phorid species parasitizingSolenopsis invicta Buren, the daily period of activity and body size are important factors to be considered in the use of these natural enemies in future programs of biological control of S. saevissima.

Effectiveness Comparison of Multiple Sticky-Trap Configurations for SamplingPseudacteonspp. Phorid Flies (Diptera: Phoridae)

A variety of traps have been developed for monitoring introduced populations of Pseudacteon spp. phorid flies (Diptera: Phoridae) across their established range in the United States. Such traps typically exploit common aspects of phorid fly biology and behavior, such as their attraction to live or dead red imported fire ants, Solenopsis invicta Buren (Hymenoptera: Formicidae), as well as the perching behavior of these parasitoids. However, populations of multiple species of phorid flies have been established in the United States to serve as biological control agents against S. invicta, and it is unclear if all trap designs are equally effective in sampling this variety of phorid species. This study investigated the effectiveness of six trap designs simultaneously during three sampling events in south-central Texas. Interactions between two species of phorid flies (Pseudacteon tricuspis Borgmeier and P. curvatus B.) and their hosts have been intensively studied at this location for over eight years. When analyzed independently, there were no significant differences in the mean number of P. curvatus or P. tricuspis phorids collected by any of the trap designs during any of the sampling events. However, when the total number of phorids collected were combined, significant trap performance differentials were observed during the October 2010 sampling event. Furthermore, there were significant differences among male flies during the September 2012 observation. Additionally, a trap component cost comparison is provided. The consistent and relatively equivalent performance of the phorid traps investigated in these trials suggests that all are appropriate for phorid surveillance, and cost and ease-of-use considerations may be the most important criteria when selecting a trap design.