Influence of host-plant quality on the performance of <Emphasis Type="Italic">Episimus unguiculus</Emphasis>, a candidate biological control agent of Brazilian peppertree in Florida

Brazilian peppertree, Schinus terebinthifolius Raddi (Sapindales: Anacardiaceae), introduced from South America, invades a variety of habitats in Florida (e.g. disturbed sites, coastal mangrove forests). The objective of this study was to evaluate the effect of host-plant quality on the performance of Episimus unguiculus Clarke (=E. utilis Zimmerman) (Lepidoptera: Tortricidae), a potential biocontrol agent of Brazilian peppertree. Experiments were conducted in the laboratory using Brazilian peppertrees exposed either to different salinity levels (0, 6, 12 parts per thousand), or to different nutrient levels (low, medium, high). Higher survival (55%) and faster development (32 day) to adulthood was observed on plants grown in fresh-water environments (0 ppt) compared to low (6 ppt) or high-salinity environments (12 ppt). In addition, higher survival (40%), faster development (34 day) and higher fertility (88% eggs hatched) occurred in high-nutrient treatments. Based on these results, field releases should be conducted in favorable habitats (e.g., low salinity, high fertility soils) to maximize the possibility of establishment and population growth of E. unguiculus in Florida. Handling Editor: John Scott.     

Host specificity of <Emphasis Type="Italic">Tectococcus ovatus</Emphasis> (Hemiptera: Eriococcidae), a potential biological control agent of the invasive strawberry guava, <Emphasis Type="Italic">Psidium cattleianum</Emphasis> (Myrtales: Myrtaceae), in Florida

Strawberry guava, Psidium cattleianum Sabine, is a woody tree or shrub native to coastal southeastern Brazil. Strawberry guava was introduced into Florida in the late 1800s as an ornamental species. The plant escaped cultivation and is invading natural areas throughout the southern half of the state. In addition to negative effects on Florida’s native ecosystems, strawberry guava also is a preferred host of the Caribbean fruit fly, Anastrepha suspensa Loew (Diptera: Tephritidae). In total, 57 plant species representing 21 families were included in the host range tests. First instar nymphs of Tectococcus ovatus Hempel fed on two closely related guava species, Brazilian guava (Psidium friedrichsthalianum O. Berg), and Costa Rican guava (Psidium guineense Sw.). However, none of the nymphs completed their development on these two non-target species. The results of the host specificity tests suggest that T. ovatus is a suitable candidate for classical biological control of strawberry guava in Florida.     

Close-Range Host Searching Behavior of the Stemborer Parasitoids <Emphasis Type="Italic">Cotesia sesamiae</Emphasis> and <Emphasis Type="Italic">Dentichasmias busseolae</Emphasis>: Influence of a Non-Host Plant <Emphasis Type="Italic">Melinis minutiflora</Emphasis>

Studies were conducted on the host searching behavior of the larval parasitoid Cotesia sesamiae (Cameron) (Hymenoptera: Braconidae) and the pupal parasitoid Dentichasmias busseolae Heinrich (Hymenoptera: Ichneumonidae), both of which attack lepidopteran (Crambidae, Noctuidae) cereal stemborers. The behavior of D. busseolae was observed in a diversified habitat that consisted of stemborer host plants (maize, Zea mays L. and sorghum, Sorghum bicolor (L). Moench (Poaceae)) and a non-host plant (molasses grass, Melinis minutiflora Beauv. (Poaceae)), while C. sesamiae was observed separately on host plants and molasses grass. In previous olfactometer studies, C. sesamiae was attracted to molasses grass volatiles while hboxD. busseolae was repelled. The aim of the present study was to investigate the influence of molasses grass on close-range foraging behavior of the parasitoids in an arena that included infested and uninfested host plants. Dentichasmias busseolae strongly discriminated between host and non-host plants, with female wasps spending most of the time on infested host plants and least time on molasses grass. Likewise, C. sesamiae spent more time on uninfested and infested host plants than it did on molasses grass in single choice bioassays. While on infested plants, the wasps spent more time foraging on the stem, the site of damage, than on other areas of the plant. Overall, the results indicate that presence of the non-host plant does not hinder close range foraging activities of either parasitoid.     

Phylogenetic analyses of <Emphasis Type="Italic">Uromyces viciae-fabae</Emphasis> and its varieties on <Emphasis Type="Italic">Vicia</Emphasis>, <Emphasis Type="Italic">Lathyrus</Emphasis>, and <Emphasis Type="Italic">Pisum</Emphasis> in Japan

A pea rust fungus, Uromyces viciae-fabae, has been classified into two varieties, var. viciae-fabae and var. orobi, based on differences in urediniospore wall thickness and putative host specificity in Japan. In principal component analyses, morphological features of urediniospores and teliospores of 94 rust specimens from Vicia, Lathyrus, and Pisum did not show definite host-specific morphological groups. In molecular analyses, 23 Uromyces specimens from Vicia, Lathyrus, and Pisum formed a single genetic clade based on D1/D2 and ITS regions. Four isolates of U. viciae-fabae from V. cracca and V. unijuga could infect and sporulate on P. sativum. These results suggest that U. viciae-fabae populations on different host plants are not biologically differentiated into groups that can be recognized as varieties.Contribution no. 184, Laboratory of Plant Parasitic Mycology, Institute of Agriculture and Forestry, University of Tsukuba, Japan     

Host specificity of <Emphasis Type="Italic">Anagrus epos</Emphasis>: a potential biological control agent of <Emphasis Type="Italic">Homalodisca vitripennis</Emphasis>

Anagrus epos Girault (Hymenoptera: Mymaridae) is a candidate for a classical biological control program targeting the glassy-winged sharpshooter (GWSS), Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae), in California. Because mass production of GWSS is expensive and labor-intensive, a factitious host that is more economical to produce is desirable to mass produce A. epos for colonization and augmentation efforts. Here, we report the results of host specificity tests and potential rearing techniques for A. epos under laboratory conditions. Females discriminated and oviposited into eggs of seven cicadellid species: H. vitripennis, Circulifer tenellus (Baker), Erythroneura variabilis Beamer, Amblysellus grex (Oman), Graphocephala atropunctata (Signoret), Macrosteles severini Hamilton, and H. liturata Ball, and two cerambycid species: Phoracantha recurva Newman and P. semipunctata (F.). Anagrus epos successfully completed development in the eggs of H. vitripennis, C. tenellus, E. variabilis, A. grex, G. atropunctata, M. severini, and H. liturata. The use of a factitious host and potential nontarget effects of this generalist parasitoid are discussed.     

Flavonoids in the leaves of <Emphasis Type="Italic">Oxalis corniculata </Emphasis>and sequestration of the flavonoids in the wing scales of the pale grass blue butterfly, <Emphasis Type="Italic">Pseudozizeeria </Emphasis><Emphasis Type="Italic">maha</Emphasis>

Three C-glycosylflavones in the leaves of Oxalis corniculata, the host plant of the lycaenid butterfly pale grass blue (Pseudozizeeria maha), were identified as 6-C-glucosylluteolin (isoorientin), 6-C-glucosylapigenin (isovitexin) and isovitexin 7-methyl ether (swertisin). Comparative spectral and HPLC analyses between the leaf extract of the host plants and the wings of P. maha showed selective uptake of the host-plant flavonoid isovitexin to the wings of the butterfly.     

The susceptibility of immature stages of <Emphasis Type="Italic">Bemisia tabaci</Emphasis> to the entomopathogenic fungus <Emphasis Type="Italic">Lecanicillium muscarium</Emphasis> on tomato and verbena foliage

Lecanicillium muscarium is a widely occurring entomopathogenic fungus. Laboratory studies were conducted to determine the efficacy of L. muscarium against different instars of Bemisia tabaci on tomato and verbena foliage after two incubation times (3 and 7 days). Significant reduction in B. tabaci numbers were recorded on fungus treated plants (p < 0.001). Second instar B. tabaci proved most susceptible to L. muscarium infection. There was no significant difference in mortality of B. tabaci second instars after either 3 or 7 days exposure to L. muscarium on either host plant. The importance of the speed of pest mortality following treatment and the potential of L. muscarium to be incorporated into an integrated pest management strategy for the biocontrol of B. tabaci on tomato and verbena plants are discussed.     

Parasitism <Emphasis Type="Italic">versus</Emphasis> mutualism in the ant-garden parabiosis between <Emphasis Type="Italic">Camponotus femoratus</Emphasis> and <Emphasis Type="Italic">Crematogaster levior</Emphasis>

Ant-gardens represent a special type of association between ants and epiphytes. Frequently, two ant species can share the same nest in a phenomenon known as ‘parabiosis’, but the exact nature (i.e., mutualistic or parasitic) of this interaction is the subject of debate. We thus attempted to clarify the mutual costs and benefits for each partner (ants and plants) in the Crematogaster levior/Camponotus femoratus ant-garden parabiosis. The ants’ response to experimental foliar damage to the epiphytes and to the host tree as well as their behavior and interactions during prey capture were investigated to see if the purported parasitic status of Cr. levior could be demonstrated in either the ant-ant or in the ant-plant interactions. The results show that both species take part in protecting the epiphytes, refuting the role of Cr. levior as a parasite of the ant-garden mutualism. During capture of large prey Ca. femoratus took advantage from the ability of Cr. levior to discover prey; by following Cr. levior trails Ca. femoratus workers discover the prey in turn and usurp them during agonistic interactions. Nevertheless, the trade-off between the costs and benefits of this association seems then to be favorable to both species because it is known that Cr. levior benefits from Ca. femoratus building the common carton nests and furnishing protection from vertebrates. Consequently, parabiosis can then be defined as the only mutualistic association existing between ant species, at least in ant-gardens. Received 31 August 2006 ; revised 8 December 2006 ; accepted 12 December 2006     

Synergistic interaction between sublethal doses of <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis> and <Emphasis Type="Italic">Campoletis chlorideae</Emphasis> in managing <Emphasis Type="Italic">Helicoverpa armigera</Emphasis>

Campoletis chlorideae Uchida (Hymenoptera: Ichneumonidae) is an important solitary larval endoparasitoid of the tomato fruit borer Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) in India. The interaction between Bacillus thuringiensis subspecies kurstaki (Btk) HD-1 and C. chlorideae was studied under laboratory condition to explore their compatibility in managing H. armigera. The results had indicated that the growth and development of H. armigera was affected in a dose-dependent manner upon feeding on sublethal doses of Btk HD-1-treated diets. There were no larval survivors in lethal doses of Btk HD-1 (LC₇₀ and LC₉₀). The growth and survival of the parasitoid were normal when the host larvae were fed with sublethal doses or subjected to short time exposure to lethal doses of Btk HD-1. However, the parasitoid offsprings developed slowly and pupal as well as adult period, adult weight and adult emergence rate were reduced significantly if the parasitoid was developing inside a severely Bt intoxicated host larvae. There were no evident differences in longevity of parasitoid adults that were fed on honey solution containing different concentrations of Btk HD-1 as compared to adults fed only on honey solution. This indicates no direct adverse effect of Btk HD-1 on C. chlorideae. Further, the gravid female parasitoid did not discriminate Btk HD-1 intoxicated and normal H. armigera larvae for oviposition. The result implies that spore crystal formulation of Btk HD-1 can be effectively used in a synergistic manner along with existing natural or prereleased population of C. chlorideae in organic farming or as components in biointensive IPM module for managing H. armigera.     

<Emphasis Type="Italic">Hieracium</Emphasis> subgen. <Emphasis Type="Italic">Pilosella</Emphasis>: pollen stainability in sexual,apomictic and sterile plants

Two pollen stainability tests (Alexander’s stain and acetocarmine) were used to detect differences in pollen viability of the sexual, apomictic and sterile plants of Hieracium subgen. Pilosella. In sexual taxa (Hieracium bauhini and H. densiflorum), the average stainability was 93.7–98.4%. Similarly high stainability (92.2–97.2%) was found in the apomictic Hieracium pilosellinum and in the majority of the apomictic populations (or plants) of the pentaploid and hexaploid H. bauhini. In some apomictic plants of Hieracium bauhini the average pollen stainability was 49.0–75.4%. The lowest pollen stainability was found in the sterile plants, i.e. the triploid H. pistoriense (33.6%) and the pentaploid H. brachiatum (29.6%).     

Novel<Emphasis Type="Italic"> eceriferum</Emphasis> mutants in<Emphasis Type="Italic"> Arabidopsis thaliana</Emphasis>

We conducted a novel non-visual screen for cuticular wax mutants in Arabidopsis thaliana (L.) Heynh. Using gas chromatography we screened over 1,200 ethyl methane sulfonate (EMS)-mutagenized lines for alterations in the major A. thaliana wild-type stem cuticular chemicals. Five lines showed distinct differences from the wild type and were further analyzed by gas chromatography and scanning electron microscopy. The five mutants were mapped to specific chromosome locations and tested for allelism with other wax mutant loci mapping to the same region. Toward this end, the mapping of the cuticular wax (cer) mutants cer10 to cer20 was conducted to allow more efficient allelism tests with newly identified lines. From these five lines, we have identified three mutants defining novel genes that have been designated CER22, CER23, and CER24. Detailed stem and leaf chemistry has allowed us to place these novel mutants in specific steps of the cuticular wax biosynthetic pathway and to make hypotheses about the function of their gene products.Abbreviations EMS Ethyl methane sulfonate - SEM Scanning electron microscopy - SSLP Simple sequence length polymorphism - WT Wild type     

Biological control of <Emphasis Type="Italic">Lantana camara</Emphasis> in South Africa: targeting a different niche with a root-feeding agent, <Emphasis Type="Italic">Longitarsus</Emphasis> sp.

The root-feeding flea beetle, Longitarsus sp. (Coleoptera: Chrysomelidae: Alticinae), was studied as a potential biological control agent for Lantana camara L. (Verbenaceae) in South Africa. Host range tests were carried out on 52 plant species in 11 families. Although 11 plant species, all in the family Verbenaceae, supported complete development of Longitarsus sp. during no-choice tests, the beetles showed very strong preferences for L. camara during paired-choice and multi-choice tests. The results confirm that the beetles have a narrow host range, and that under natural conditions they are highly unlikely to utilise plants other than L. camara. In the unlikely event that some of the Lippia spp. are attacked in the field, they are not expected to sustain populations of the flea beetle over time. Attributes that should enhance the biocontrol potential of Longitarsus sp. include: the adults are long-lived and highly mobile; and, the larvae cause extensive direct damage to the roots of L. camara, which could in turn expose the plants to soil-born pathogens. All indications are that Longitarsus sp. could make a substantial contribution to the biological control of L. camara in many countries around the world because the beetles pose no threat to non-target plant species and they damage a part of the plant (i.e. roots) not yet affected by any other agent species.     

The ontogenetic basis for floral diversity in <Emphasis Type="Italic">Agonis</Emphasis>, <Emphasis Type="Italic">Leptospermum</Emphasis> and <Emphasis Type="Italic">Kunzea</Emphasis> (Myrtaceae)

Floral development in three species each of Leptospermum and Kunzea, and one species of Agonis, is described and compared. Differences in the number of stamens and their arrangement in the flower at anthesis are determined by the growth dynamics of the bud. In Leptospermum, early expansion of the bud is predominantly in the axial direction and causes the stamen primordia to be initiated in antepetalous chevrons. In Kunzea, early expansion occurs predominantly in the lateral direction and successive iterations of stamen primordia are inserted alternately at more or less the same level. In both genera, further expansion in the lateral plane spreads the stamens into a ring around the hypanthium. Agonis flexuosa is similar to Leptospermum. Other variable factors include the timing at which stamen initiation commences (earlier in Leptospermum than Kunzea), the duration of stamen initiation (hence the total number of stamens produced – varies within genera), and very late differential expansion that forces stamens into secondary antesepalous groups in A. flexuosa and L. myrsinoides.The authors thank Dr H. Toelken for kindly providing some material and the impetus for this project. This research was supported by Australian Research Council grant AS19131815.     

The <Emphasis Type="Italic">Caenorhabditis</Emphasis><Emphasis Type="Italic">briggsae</Emphasis> genome contains active <Emphasis Type="Italic">CbmaT1</Emphasis> and <Emphasis Type="Italic">Tcb1</Emphasis> transposons

The maT clade of transposons is a group of transposable elements intermediate in sequence and predicted protein structure to mariner and Tc transposons, with a distribution thus far limited to a few invertebrate species. We present evidence, based on searches of publicly available databases, that the nematode Caenorhabditis briggsae has several maT-like transposons, which we have designated as CbmaT elements, dispersed throughout its genome. We also describe two additional transposon sequences that probably share their evolutionary history with the CbmaT transposons. One resembles a fold back variant of a CbmaT element, with long (380-bp) inverted terminal repeats (ITRs) that show a high degree (71%) of identity to CbmaT1. The other, which shares only the 26-bp ITR sequences with one of the CbmaT variants, is present in eight nearly identical copies, but does not have a transposase gene and may therefore be cross mobilised by a CbmaT transposase. Using PCR-based mobility assays, we show that CbmaT1 transposons are capable of excising from the C. briggsae genome. CbmaT1 excised approximately 500 times less frequently than Tcb1 in the reference strain AF16, but both CbmaT1 and Tcb1 excised at extremely high frequencies in the HK105 strain. The HK105 strain also exhibited a high frequency of spontaneous induction of unc-22 mutants, suggesting that it may be a mutator strain of C. briggsae.     

Biology, host specificity tests, and risk assessment of the sawfly Heteroperreyia hubrichi, a potential biological control agent of Schinus terebinthifolius in Hawaii

Heteroperreyia hubrichiMalaise (Hymenoptera: Pergidae), a foliagefeeding sawfly of Schinusterebinthifolius Raddi (Sapindales:Anacardiaceae), was studied to assess itssuitability as a classical biological controlagent of this invasive weed in Hawaii. No-choice host-specificity tests were conductedin Hawaiian quarantine on 20 plant species in10 families. Besides the target weed, adultfemales oviposited on four test species. Females accepted the Hawaiian native Rhussandwicensis A. Gray (Sapindales:Anacardiaceae) as an oviposition host equallyas well as the target species. The other threespecies received significantly fewer eggs. Neonate larvae transferred onto test plantssuccessfully developed to pupae on S.terebinthifolius (70% survival) and R.sandwicensis (1% survival). All other 18test plant species failed to support larvaldevelopment. A risk analysis was conducted toquantify the acceptability of non-targetspecies as host plants for H. hubrichi onthe basis of the insect's performance atvarious stages in its life cycle. Risk ofdamage to all plant species tested wasinsignificant except for R. sandwicensis. Risk to this native plant relative to S.terebinthifolius was estimated at 1%. Currently this level of risk is too high torequest introduction of this insect into theHawaiian environment. Detailed impact studiesin the native range of S. terebinthifoliusare needed to identify thepotential benefit that this insect offers. Also, field studies in South America withpotted R. sandwicensis would give a morereliable analysis of the risk this nativeHawaiian plant would face from naturalpopulations of H. hubrichi.     

<Emphasis Type="Italic">Agrobacterium</Emphasis>-mediated transformation of Perilla (<Emphasis Type="Italic">Perilla frutescens</Emphasis>)

Agrobacterium tumefaciens-mediated transformation system for perilla (Perilla frutescens Britt) was developed. Agrobacterium strain EHA105 harboring binary vector pBK I containing bar and γ-tmt cassettes or pIG121Hm containing nptII, hpt, and gusA cassettes were used for transformation. Three different types of explant, hypocotyl, cotyledon and leaf, were evaluated for transformation and hypocotyl explants resulted in the highest transformation efficiency with an average of 3.1 and 2.2%, with pBK I and pIG121Hm, respectively. The Perilla spp. displayed genotype-response for transformation. The effective concentrations of selective agents were 2 mg l⁻¹ phosphinothricin (PPT) and 150 mg l⁻¹ kanamycin, respectively, for shoot induction and 1 mg l⁻¹ PPT and 125 mg l⁻¹ kanamycin, respectively, for shoot elongation. The transformation events were confirmed by herbicide Basta spray or histochemical GUS staining of T₀ and T₁ plants. The T-DNA integration and transgene inheritance were confirmed by PCR and Southern blot analysis of random samples of T₀ and T₁ transgenic plants.     

Effects of Gall Induction by <Emphasis Type="Italic">Epiblema Strenuana</Emphasis> on Gas Exchange,Nutrients, and Energetics in <Emphasis Type="Italic">Parthenium Hysterophorus</Emphasis>

Gall induction by arthropods results in a range of morphological and physiological changes in their host plants. We examined changes in gas exchange, nutrients, and energetics related to the presence of stem galls on Parthenium hysterophorus L. (Asteraceae) induced by the moth, Epiblema strenuana Walker (Lepidoptera: Tortricidae). We compared the effects of galls on P. hysterophorus in the rosette (young), pre-flowering (mature), and flowering (old) stages. Gall induction reduced the leaf-water potential, especially in flowering stage plants. In young and mature stage plants, galling reduced photosynthetic rates considerably. Gall induction reduced the transpiration rate mostly in mature plants, and this also diminished stomatal conductance. Energy levels in most galls and in shoot tissue immediately below the galls were significantly higher than the energy levels in stem tissue immediately above the galls, indicating that the gall acts as a mobilizing sink for the moth. Galling had significant effects on concentrations of minerals such as boron, chloride, magnesium, and zinc. In galled plants, reduced leaf-water potential and reduced rates of photosynthesis, transpiration, and stomatal conductance may have altered mineral element levels. These observed effects demonstrate that E. strenuana has the potential to regulate P. hysterophorus.     

Three new species of <Emphasis Type="Italic">Luetzelburgia</Emphasis> (<Emphasis Type="Italic">Leguminosae</Emphasis>, <Emphasis Type="Italic">Papilionoideae</Emphasis>) from the caatinga of Bahia,Brazil and an identification key to all species of the genus

Three new species of the Brazilian genus Luetzelburgia Harms (Leguminosae, Papilionoideae, Sophoreae sensu lato (Vataireoid clade)) are described and illustrated under the names Luetzelburgia harleyi D. Cardoso, L. P. Queiroz &; H. C. Lima, L. neurocarpa D. Cardoso, L. P. Queiroz &; H. C. Lima and L. purpurea D. Cardoso, L. P. Queiroz &; H. C. Lima. All three occur in the caatinga vegetation of the State of Bahia, Eastern Brazil. A discussion of the morphological characters distinguishing the new species from their close relatives, as well as an identification key to all known species of Luetzelburgia, are presented.     

Production and analysis of intergeneric somatic hybrids between <Emphasis Type="Italic">Brassica oleracea</Emphasis> and<Emphasis Type="Italic"> Matthiola incana</Emphasis>

The gene pool of Brassica oleracea was enriched via intergeneric somatic hybridization between B. oleracea (2n = 18) and Matthiola incana (2n = 14). One hundred and eighteen plants were obtained from 96 calli. Only four plants (H1, H2, H3 and H4) showed an intermediate phenotype from the parents; among these, H1 and H3 arose from the same callus. Random amplified polymorphic DNA (RAPD), sequence-related amplified polymorphism (SRAP), and cytological analyses confirmed that H1 and H3 were hybrids. The nuclear DNA content of the regenerated plants was determined by flow cytometry. More than half of the plants contained a nuclear DNA content of 1.3 to 3.9 pg/cell, which was higher than the content of B. oleracea but lower than that of M. incana. H1 contained 4.89 ± 0.02 pg of DNA per cell, while H3 nuclear DNA content was estimated at 4.87 ± 0.06 pg/cell. Cytological study of the root-tip cells revealed that the majority of the H1 and H3 hybrid cells contained 28 chromosomes.     

Phenology and parasitism rates in introduced populations of <Emphasis Type="Italic">Pseudacteon tricuspis</Emphasis>, a parasitoid of <Emphasis Type="Italic">Solenopsis invicta</Emphasis>

We documented patterns of seasonal abundance and rates of parasitism in introduced populations of Pseudacteon tricuspis Borgmeier, a phorid parasitoid of the red imported fire ant, Solenopsis invicta Buren. Adult P. tricuspis populations were censused at monthly intervals for 1 year at three sites in northern Florida. Censuses were conducted by aspirating phorids attracted to disturbed S. invicta mounds. Pseudacteon tricuspis adults were present in every month at all sites, although abundances varied greatly among sites and over time. The highest densities of flies (up to 453 censused at 10 disturbed S. invicta mounds in 30 min) were observed in November, and changes in abundance over time were positively correlated among sites. Sex ratios were usually male biased. Parasitism rates were evaluated by collecting workers from field colonies and monitoring them in the laboratory for evidence of parasitism. Parasitism rates were very low – always less than 1%. The average parasitism rate per colony over 16 colonies and 2 years was 0.058%. No pupariation occurred within the first 8 days of collection, suggesting parasitism by P. tricuspis induced behavioral changes in parasitized workers that precluded such workers from our collections. If so, true field parasitism rates may be several times higher than measured here, yet still low in an absolute sense. These low parasitism rates can be reconciled with observed adult phorid densities by considering the large number of host ants present at the study sites.