A field survey was conducted in the summer of 2003 and 2004 to evaluate resistance to deltamethrin on house flies, Musca domestica, from 17 urban garbage dumps in the cities of Beijing, Tianjin, and Zhangjiakou. Bioassays were carried out by topical application with technical deltamethrin to measure the levels of resistance to deltamethrin. Tests for synergism with piperonyl butoxide (PBO) were used to study the occurrence of metabolic resistance mechanisms. Competitive polymerase chain reaction (PCR) amplification of specific allele (cPASA) assay was used on individual house flies from these field populations to detect the presence of the kdr and super-kdr alleles associated with pyrethroid resistance. Another PCR followed by labeled allele-specific oligonucleotide hybridization (PCR-ASO) confirmed the presence of the mutation and hence checked the accuracy of cPASA. Deviation of genotype ratios from Hardy-Weinberg equilibrium was tested. Relative to a susceptible laboratory strain, field house flies from all populations exhibited a 13- to 250-fold greater resistance to deltamethrin in all the populations of house flies at the LD₅₀ and the PBO synergism coefficient was 26- to 124-fold greater in 11 populations collected from Beijing. The super-kdr allele was not found in any of the populations. Results of PCR assays showed that the kdr allele was present at various frequencies in the field populations. ASO-PCR showed that the cPASA method had given only 1 of 33 of false positives. Deviation of frequencies of kdr alleles genotypes from the Hardy-Weinberg ratios was found in the BJF-1, BJF-2, BJF-3, BJHD, and BJXC populations. Regression analysis indicated a significant correlation between kdr allele frequencies and the levels of resistance to knockdown resistance by deltamethrin. The results validate the role of the PCR-based molecular assay as a diagnostic tool in monitoring resistance to pyrethroids and also to provide useful information on population genetics of house fly resistance to pyrethroids.

Life history data for Aphidius gifuensis (Ashmead) and Myzus persicae (Sulzer) were collected in the laboratory. To consider both sexes and variable developmental rates among individuals, the raw data were analyzed using the age-stage, two-sex life table. The intrinsic rate of increase (r) for A. gifuensis is 0.264 d⁻¹. The mean parasitism rate is 92.3 aphids per female. The intrinsic rate of increase for M. persicae is 0.252 d⁻¹. For applying the female age-specific life table to a female population, we prove that the relationship between the mean female fecundity (F) and the net reproductive rate (R₀) is R₀ = s_aF, where s_a is the preadult survival rate. When the female age-specific life table is applied to two-sex populations, the relationship between F and R₀ is R₀ = s_awF, where s_a is the preadult survival rate of females, and w is the female proportion in offspring. This is valid when w is a constant for the age-specific fecundity (m_x) of all ages. Because sexing preadult individuals is difficult, and obtaining a constant sex ratio in offspring is uncertain, determining preadult mortality of the individual sexes may be problematical. As a result, calculations of the age-specific survival rate (l_x) and fecundity and population parameters may be adversely affected. Moreover, if l_x and m_x are constructed based on adult age, they may also cause errors in population parameters. Because the application of female age-specific life table to stage-structured bisexual population results in inaccuracies, we recommend that the age-stage, two-sex life table should be used in insect demographic studies.

We evaluated whether Dendroctonus frontalis Zimmermann populations were influenced by nontrophic interactions involving commensal mites, their mutualistic bluestain fungus Ophiostoma minus (Hedgc.) H. and P. Sydow, and beetle-mutualistic mycangial fungi. We tested for effects of delayed, nonlinear, or positive feedback from O. minus and mites on D. frontalis population growth. We predicted that (1) high mite densities have demographic consequences for beetles by influencing the prevalence of O. minus and antagonistic interactions between O. minus and mycangial fungi, and (2) inter-relations and abundances of mites and fungi differentially vary throughout the year in a seasonally variable climate. Surveys of D. frontalis populations revealed that temporal and spatial patterns in abundance of mites and their mutualistic fungus, O. minus were inversely related with beetle population growth. Negative demographic effects of O. minus on D. frontalis were nonlinear, only affecting beetle per capita reproduction when fungi colonized >35% of phloem habitat. Mite abundance was strongly correlated with O. minus and was an important driving force in promoting bluestain prevalence within trees. Spring abundances of mites and the prevalence of O. minus during D. frontalis infestation formation were strong predictors of beetle population decline later that year. The two mutualistic fungi associated with D. frontalis cycled seasonally but did not seem to influence beetle population dynamics.

The primary objective of this experiment was to assess the impacts of ant tending by the Argentine ant, Linepithema humile, on myrmecophilous and nonmyrmecophilous herbivores of Baccharis halimifolia, through field manipulations of ant attendance levels. High and low levels of ant attendance were established for a 5-mo evaluation of the densities of ant attended aphids, aphid predators, and leaf miners, which are subject to ant-induced damage of the mines. High levels of ant attendance resulted in significantly higher densities of both aphids and their predators over the course of the 5-mo experiment. A complementary short-term (20-d) experiment revealed that (1) aphid populations in ant-attended colonies increased in size and persisted longer than those in non–ant-attended colonies, and (2) aphid predators remained more abundant on non–ant-attended aphid colonies until the colonies went locally extinct. There were no significant effects of ants on the densities of the two common leaf miners, Amauromyza maculosa and Liriomyza trifolii, despite a significantly greater number of ant-damaged mines on trees in the high ant density treatment. The results of this experiment suggest that ant tending by L. humile on B. halimifolia may only impact those insects normally involved in the ant–aphid mutualism and not all herbivores of this host plant.

Ponderosa pine forests in northern Arizona have historically experienced limited bark beetle-caused tree mortality, and little is known about the bark beetle community in these forests. Our objectives were to describe the flight seasonality and lure preference of bark beetles and their associates in these forests. We monitored bark beetle populations for 24 consecutive months in 2002 and 2003 using Lindgren funnel traps with five different pheromone lures. In both years, the majority of bark beetles were trapped between May and October, and the peak captures of coleopteran predator species, Enoclerus (F.) (Cleridae) and Temnochila chlorodia (Mannerheim), occurred between June and August. Trap catches of Elacatis (Coleoptera: Othniidae, now Salpingidae), a suspected predator, peaked early in the spring. For wood borers, trap catches of the Buprestidae family peaked in late May/early June, and catches of the Cerambycidae family peaked in July/August. The lure targeted for Dendroctonus brevicomis LeConte attracted the largest percentage of all Dendroctonus beetles except for D. valens LeConte, which was attracted in highest percentage to the lure targeted for D. valens. The lure targeted for Ips pini attracted the highest percentage of beetles for all three Ips species [I.pini (Say), I. latidens (LeConte), and I. lecontei Swaine] and the two predators, Enoclerus and T. chlorodia. The lures targeted for D. valens and I. pini attracted the highest percentage of beetles in the Elacatis genus and the Cerambycidae family. Beetles in the Buprestidae family showed no strong preference for any lure type.

Potential host plants for the larvae of plum curculio, Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae), in central Georgia’s peach producing region were surveyed. This fruit-attacking curculionid is reported to have a broad host range, including many plants in the Rosaceae and other families. However, our collections indicated that in this region plum curculio largely is limited to peach (Prunus persica) and plum (P. angustifolia and P. umbellata). Abandoned peach orchards and wild plum thickets are important hosts for the spring generation of plum curculio and are sources of subsequent infestations of managed peach orchards. However, only abandoned peach orchards were available to the summer generation of plum curculio. May haw, Crataegus aestivalis, was also a host, but other species of Crataegus were not used. Although the plum curculio was reported to be a significant pest of blueberries (Vaccinium spp.) in North Carolina, New Jersey, and Delaware, they were only rarely used as a host in central Georgia. Apple (Malus domestica) and Asian pear (Pyrus pyrifolia), when available, were ovipositional hosts of plum curculio in central Georgia; however, no larvae emerged from these hosts. We report the first records of plum curculio developing in Vaccinium stamineum and Vitis rotundifolia. Our results are compared with a previous survey conducted in the northeastern United States, as well as to data reported in the literature.

Specialist-feeding phytoseiid mites have a well-documented role in biological control of phytophagous spider mites. However, although there is evidence for the importance of generalist-feeding phytoseiid mites in spider mite suppression, their role is less clear than that of specialists. The effectiveness of generalists as biocontrol agents and their interactions with specialists might be directly influenced by canopy structure or indirectly affected by altering plant microclimate. We manipulated densities of generalist phytoseiid mites and canopy size (large and small) in open-field experiments in an abandoned vineyard. In the first experiment, we increased generalist densities by transferring grapevine foliage housing robust generalist populations, whereas in the second experiment, we lowered generalist densities using the broad-spectrum insecticide chlorpyrifos. In both experiments, we also altered canopy size by tying grapevine shoots. Increasing densities of generalists resulted in lower spider mite densities. Generalists initially decreased densities of specialist phytoseiid mites as well, although specialist densities rebounded as spider mite densities increased later in the experiment. Lowering generalist densities appeared to slightly increase densities of both spider and specialist mites, consistent with the first experiment. However, these effects were not statistically significant, possibly because the reduction in generalist densities through chlorpyrifos application was not as dramatic as our generalist augmentation in the first experiment. Canopy size did not significantly affect pest or predatory mite densities in either experiment. These field experiments demonstrate that generalists can slow spider mite population growth in grapes. In contrast, canopy architecture appeared to have little impact on spider mite biocontrol.

Surveys were conducted to identify the weeds bordering Hawaiian pineapple plantings that could serve as hosts for the pink pineapple mealybug, Dysmicoccus brevipes (Cockerell). Collected mealybugs were held to determine parasitization by the encyrtid Anagyrus ananatis Gahan. Greater than 15 species of weeds were found around pineapple plantings in both disturbed (e.g., mowed, herbicide treated, manual weed removal) and undisturbed areas. Weed diversity was low in the undisturbed areas with guinea grass, Panicum maximum, being the dominant species and free of pink pineapple mealybug. Weed species composition was more diverse in the disturbed areas adjacent to plantings, with routinely mowed areas being more diverse. Although pink pineapple mealybug is a polyphagous mealybug, it was only found in moderate densities on rhodesgrass, Chloris gayana, and wire grass, Eleusine indica, both of which were found in mowed and unmowed weedy areas with the former species being more common. All phenological stages of rhodesgrass were infested with pink pineapple mealybugs, but only mature wire grass plants were infested. None of the pink pineapple mealybugs collected from the weeds produced parasitoids, which suggests that the most common weeds found during these studies did not serve as reservoirs for A. ananatis. Because some common weed species harbored Dysmicoccus mealybugs, weed management could play a significant role in reducing pink pineapple mealybug movement into pineapple plantings.

Weekly releases of Muscidifurax raptorellus Kogan and Legner and Spalangia cameroni Perkins were made for 12 wk after house cleanouts in Florida pullet houses in either spring/summer (May–August) or fall (September–December). Releases were made by weekly placement of 62,500 and 85,000 pupae parasitized by M. raptorellus and S. cameroni, respectively, which produced an average of 79,049 and 32,841 adult female parasitoids per week. House fly (Musca domestica L.) pupal mortality, as measured by sentinel pupae, was about twice as high in the release house (40.2%) as in the two control houses (21.5 and 21.8%) in the summer release. Pupal mortality in the fall was three to four times higher in the release house (45.6%) as in the two control houses (13.6 and 8.4%). Although successful parasitism of sentinel pupae was only ≈8.4% in the release houses in both studies, parasitism was significantly higher than the control houses in both summer (3.9 and 1.7%) and fall (0.0 and 0.8%) releases. Fly populations were high in both studies but significantly lower in the release houses than the controls in both summer (361.5 versus 450.3 and 584.4 spots/spot card/wk) and fall (477.1 versus 971.4 and 851.8 spots/card/wk) releases. An average of 4.8 M. raptorellus emerged from each pupa parasitized by this species, with parasite loads ranging from 1 (8.6%) to 17 (0.07%) adults emerged per parasitized pupa.

In a previous study, we showed that female Hessian fly, Mayetiola destructor (Say), oviposits significantly fewer eggs on susceptible wheat plants attacked by conspecific larvae. Here we tested whether proximate cues for reduced egglaying on larval-occupied plants are associated with larvae per se or plant-based cues related to larval attack. We used a novel method, i.e., R gene–defended wheat Triticum aestivum L. genotypes, to decouple Hessian fly larvae from their effects on the plant. On R gene–defended plants, Hessian fly larvae survive for up to 5 d but do not grow. A comparison of egglaying patterns on four near-isogenic wheat genotypes, a susceptible control ‘Newton’ and three R gene wheat genotypes expressing the H6, H9, or H13 gene, showed that the presence of live larvae on plants was not the cause of reduced egglaying. Growth deficits in the youngest leaves, a well-known plant response to Hessian fly larval attack, also were examined as a possible cause of reduced oviposition but showed no consistent relationship with egg numbers. We conclude that Hessian fly females have additional means of distinguishing between larval-occupied and unoccupied plants, perhaps by detecting chemical cues associated with plant stress.

The cabbage aphid (Brevicoryne brassicae L.) is the primary broccoli (Brassica oleracea L.) pest in Monterey County. These aphids’ ability to contaminate a broccoli head has sometimes led to zero-tolerance spray thresholds. To improve on these management practices, aphid arrival time, within-plant colony location, and abundance of natural enemies were tested against infestation of organic broccoli heads at harvest. Cabbage aphids predominately colonized the outer leaves of a broccoli plant. These colonies, however, did not significantly influence infestation at harvest. Center-located aphids were correlated with head infestation for both field seasons, as were aphids on leaf 2 in 2002. Aphid arrival time into a field was strongly correlated with infestation at harvest, with early arriving aphids being less likely to infest a head. This was in part caused by natural enemies, particularly syrphid larvae (Syrphidae), which were in greatest abundance in response to early aphid colonizers. Natural enemies showed a capability to positively affect infestation at harvest, although their success seemed dependent on sufficient early season cabbage aphid arrivals. Therefore, future research efforts should focus on management practices that encourage the early establishment of natural enemies.

Several sampling methods were used to determine the number of rice stink bugs, Oebalus pugnax (F.) in rice, Oryza sativa L., fields and grassy margins. Significantly more adult stink bugs were swept in fields of ‘Wells’ than ‘Francis’, ‘Cypress’, or ‘Bengal’. Sweep net sampling in the cooler parts of the day (0900 and 1900 hours CDT) captured significantly more rice stink bugs than in the heat of the day at 1330 hours CDT. In 2002, yellow pyramid traps were set out before rice heading. These traps captured more rice stink bugs from 5 June (before rice heading) to 12 July (75% rice heading) than during rice heading from 12 to 22 July. Significantly more rice stink bugs were visually counted on grass panicles and swept from grassy hosts in margins adjacent to rice fields from 28 June to 12 July than recorded after 12 July. During rice heading, rice stink bugs were dispersing into rice fields as noted by significantly greater counts of rice stink bugs per 10 sweeps in the rice field than at other rice growth periods sampled. After harvest, pyramid trap catches increased in late September to >20 bugs per trap but dropped to below 1 bug per trap after 3 October and to 0 by 1 November. In 2003, counts of rice stink bugs during the preheading, rice heading, and postheading periods from traps, sweep net samples of the field margins, and rice fields were similar to that in 2002. Pest sampling and management options are discussed.

Hemlock woolly adelgid (Adelges tsugae Annand) is an invasive insect pest that is causing widespread mortality of eastern hemlock. However, some stands remain living more than a decade after infestation. To date, this has been attributed to site and climatic variables. This multi-tiered study examines the role foliar chemistry may play in A. tsugae success and subsequent hemlock decline. Comparisons of resistant and susceptible hemlock species indicate higher concentrations of P and lower concentrations of N in resistant species. On experimentally colonized hemlocks, the numbers of live sistens present after two A. tsugae generations was correlated with higher K and lower P concentrations. A regional T. canadensis monitoring effort showed that concentrations of Ca, K, N, and P were most strongly correlated with A. tsugae densities, which was the driving factor in hemlock decline. From the results of this study, we hypothesize that higher N and K concentrations may enhance hemlock palatability, thereby increasing A. tsugae population levels, whereas higher concentrations of Ca and P may deter more severe infestations. Foliar chemistry alone can explain over one-half of the variability in hemlock decline witnessed at 45 monitoring plots across the northeastern United States. Combining chemistry and traditional site factors, an 11-class decline rating could be predicted with 98% 1-class tolerance accuracy on an independent validation set. These results suggest that foliar chemistry may play a role in eastern hemlock susceptibility to A. tsugae infestation and should be included in risk assessment models.

Eurasian watermilfoil (Myriophyllum spicatum L.) is a non-native, aquatic, invasive species common throughout North America. The native aquatic milfoil weevil (Euhrychiopsis lecontei Dietz), whose natural host is the native northern watermilfoil (Myriophyllum sibiricum Komarov), has expanded its range to include M. spicatum. Previous studies show that it prefers the non-native Eurasian watermilfoil over native watermilfoils for feeding and oviposition. Previous studies also suggest that milfoil weevils that develop on M. spicatum have shorter development times and a greater mass. Eurasian watermilfoil and northern watermilfoil have hybridized, and hybrids can be more invasive than their parent species. One hypothesized mechanism for increased invasiveness in the hybrid watermilfoil is resistance to the milfoil weevil. To test for resistance, we compared development times, mass, and survival of the milfoil weevil reared on Eurasian, northern, and the Eurasian × northern hybrid watermilfoils. We followed weevil development from egg to adult on individual rooted plants (n = 17–20 for each taxon) in laboratory experiments at 26°C. Neither development times (total and individual stages) nor adult eclosion mass were significantly different among hosts. Mean development time from egg to adult ranged from 19.7 to 20.3 d, and mean mass ranged from 1.3 to 1.5 mg. Weevil survival rates differed significantly among the taxa and were lowest on northern watermilfoil (45%), intermediate on the hybrid (61%), and highest on Eurasian watermilfoil (88%), but stem diameter may account for some of these differences. This study suggests that hybrid watermilfoil is not exceptionally resistant to milfoil weevil herbivory but rather possesses resistance intermediate between the native and exotic hosts.

In 2003 and 2004, field studies were conducted at three sites in Zhejiang Province in China to assess the impacts of Bacillus thuringiensis (Bt) Berliner rice expressing a fused gene of cry1Ab and cry1Ac on nontarget planthoppers and leafhoppers. Populations in Bt plots were sampled with yellow sticky card traps, Malaise traps, and a vacuum-suction machine, and compared with samples from non-Bt control (IR72) plots. The results from yellow sticky card trap samplings indicated no significant differences between Bt and non-Bt plots in the species composition or densities of each species of planthopper and leafhopper. Three species of planthoppers, Sogatella furcifera (Horvath), Nilaparvata lugens (Stål), and Laodelphax striatellus (Fallén), were collected at all sites, and three species of leafhoppers, Nephotettix cincticeps (Uhler), Thaia subrufa (Motschulsky), and Recilia dorsalis (Motschulsky), were collected at Hangzhou. Another species of leafhopper, N. virescens (Distant), was collected at Anji and Jiande instead of T. subrufa. The results from the Malaise trap and vacuum-suction samples revealed no significant differences between Bt and non-Bt plots in species structure of planthoppers and leafhoppers or in population changes of the predominant planthopper species, S. furcifera, the predominant leafhopper species, N. cincticeps, or N. virescens throughout most sampling dates. Densities of planthoppers and leafhoppers were significantly affected by year and site but not by Bt rice. In general, our results suggest that the Bt rice line tested did not adversely affect nontarget planthopper and leafhopper populations and will not lead to higher populations or damage by planthoppers and leafhoppers.

A dietary exposure bioassay with larvae of the ground beetle, Poecilus chalcites (Say) (Coleoptera: Carabidae), was developed to assess potential nontarget impacts of corn event MON 863 expressing the Cry3Bb1 protein for control of corn rootworms, Diabrotica spp. (Coleoptera: Chrysomelidae). The assay involved 28 d of continuous exposure of P. chalcites larvae to an artificial diet treated with a maximum hazard dose (930 μg/g of diet) of the Cry3Bb1 protein. Results from this study showed that the Cry3Bb1 protein at a concentration of 930 μg/g of diet had no adverse effect on the survival, development, and growth (biomass) of P. chalcites larvae. Furthermore, statistical power analysis indicated that at levels of 80% power and 5% type I error rate, the study design would have been able to detect a minimum 14 (at day 7) to 19% (at days 14, 21, and 28) reduction in survival and a 21 (at day 14) to 18% (at day 28) reduction in biomass of test larvae relative to the negative buffer control groups. Based on the maximum level (93 μg/g) of the Cry3Bb1 protein expressed in MON 863 corn tissues including leaves, roots, and pollen, findings from this study indicate that corn hybrids containing the MON 863 event have a minimum 10 times safety factor for larvae of P. chalcites, and thus pose little risk to this nontarget beneficial insect.

Laboratory feeding experiments using transgenic Bacillus thuringiensis (Bt) cotton plants were carried out to evaluate the transmission of Bt toxin among trophic levels and the effects of Bt-fed herbivorous prey on the coccinellid predator Propylaea japonica (Thunberg). The experimental host plants were transgenic Bt-expressing cotton cultivars, NuCOTN 33B and GK-12 and one corresponding untransformed isogenic (non-Bt) cultivar. The herbivorous prey, cotton aphid Aphis gossypii Glover, was not sensitive to Bt toxin. Trace amounts of Bt toxins (6.0 ng/g fresh mass [FM] in GK-12, 4.0 ng/g FM in NuCOTN 33B) were detected in A. gossypii feeding on Bt cotton cultivars. Bt toxin was detected in ladybirds preying on Bt-fed aphids, and its quantity increased as the predatory period extended (5–20 d). Small amounts of Bt toxin was also found in newly hatched, unfed coccinellid larvae when their parents fed on NuCOTN 33B-reared aphids (15.0 ng/g FM), but not when the parents were fed on GK-12–reared prey. In experiments assessing life history consequences, mortality was low (mean = 7.9%), confirming that the rearing methods were appropriate. There were no distinct differences in preimaginal mortality between predators reared on Bt-fed or Bt-free aphids. The preimaginal stages of the ladybird beetles developed faster when reared on prey fed on either Bt-cotton cultivar than those fed control prey. There was a trend of more adult malformations when the predator was fed with prey from one (GK-12) but not the other of the Bt cotton cultivars than on control prey. There were no significant differences in the preovipositing period or in fecundity. Ladybird beetles preying on Bt-reared aphids matured faster and mated more frequently than those fed on Bt-free aphids. These results indicate that Bt toxin expressed in transgenic cotton cultivars can be transmitted to a higher trophic level through a nontarget pest insect and may alter the biology and behavior of a predatory ladybird. Further work should evaluate the possible long-term, sublethal impacts on the agroenvironment under field conditions.

The Formosan subterranean termite, Coptotermes formosanus Shiraki, is a major invasive pest species in many parts of the world. We compared the colony breeding system and population genetic structure in three introduced populations in the continental United States: Charleston, SC; City Park, New Orleans, LA; and Rutherford County, NC. Based on worker genotypes at 12 microsatellite loci, we found that colonies were mainly genetically distinct entities consisting of either simple families headed by monogamous pairs of reproductives or extended families containing multiple neotenic (replacement) reproductives descended from simple families. Populations varied from 48% simple families in Charleston to 82% simple families in City Park. Extended family colonies in all three populations were likely headed by <10 neotenic reproductives. There was no significant isolation by distance in any of the populations, suggesting that colonies reproduce by relatively long-range mating flights and/or human-mediated dispersal within each population. The Charleston population showed evidence of a recent genetic bottleneck and most likely was founded by very few colonies. Cluster analysis indicated that the Charleston and City Park populations are quite genetically distant from each other and most likely originated from different source populations. The more recently introduced Rutherford County population was genetically most similar to City Park. These findings, together with results from other infested sites, indicate considerable variation in the genetic structure and breeding system of introduced populations of this species, making it unlikely that there is a simple genetic or behavioral explanation for the success of C. formosanus as an invasive species.

The social forms of the red imported fire ant, initially discovered in Taoyuan County in 2003, were determined based on Gp-9 allele identification. Both polygynous and monogynous colonies were found. It was also found that, in almost all of townships surveyed, there was tendency to have more polygynous nests than monogynous nests. The monogynous nests were indeed authentic monogynous nests without contamination of the cryptic b-prime allele from South America. Sequence comparison revealed that polygynous colonies in Taiwan contained either the Gp-9^B1 or Gp-9 ^B3 variant (Sinv.B1 and Sinv.B3 in GenBank) of the B allele, whereas some of the monogynous colonies contained a Gp-9^B2–like variant of the B allele (Sinv.B2 in GenBank). Gp-9 ^B1 also was found in some monogynous colonies. The scenario of a single introduction by a founding polygynous colony with all of the monogynous nests being descendents of this polygynous nest was also ruled unlikely because of the presence of the monogyne-specific B2 allele. These findings favor multiple origins of the red imported fire ant in Taiwan.

We used microsatellite and mtDNA markers to compare colony and population genetics of two sympatric species of subterranean termites, Reticulitermes flavipes (Kollar) (n = 25 colonies) and R. hageni Banks (n = 16 colonies), in two sites located 27 km apart in the Piedmont of central North Carolina. Colony breeding structure was inferred by examination of microsatellite genotypes of workers within colonies and by estimates of nestmate relatedness and hierarchical F-statistics. Similar to previous results on this species, nearly one-half of the R. flavipes colonies were simple families mainly headed by outbred primary (alate-derived) reproductives, about one-half were comprised of extended (inbred) families inferred to be headed by low numbers of neotenics (non alate-derived secondary reproductives) descended from the original primary pair, and two colonies contained the offspring of multiple reproductives. About two-thirds of the R. hageni colonies were comprised of simple families largely headed by related reproductives, and about one-third consisted of extended families headed by low numbers of neotenics. R. hageni differed from R. flavipes in having significant isolation by distance at one site as well as significant differentiation between sites at both the microsatellite and mtDNA markers. We conclude that dispersal in R. hageni is more limited resulting in higher levels of inbreeding within colonies and greater degrees of population genetic structure at small and large spatial scales than in sympatric populations of R. flavipes. These results indicate that closely related species of subterranean termites occurring in the same habitat can differ in their breeding systems with important consequences for higher level genetic structure.