Attractiveness of bait matrices and matrix/toxicant combinations to the citrus pests Iridomyrmex purpureus (F.Smith) and Iridomyrmex rufoniger gp sp. (Hym., Formicidae)

Abstract: Six bait matrices were tested for palatability to the ants Iridomyrmex purpureus and I. rufoniger gp sp., which are important pests of citrus in south‐eastern Australia. Granulated citrus pulp and rice bran impregnated with brown sugar were not accepted by either species, but ground dry dog food and ground insects (with or without added sugar) were highly attractive to both ant species. The ground dog food was impregnated with various toxicants at concentrations of up to 1% (w/w) and tested for palatability to both ant species. Technical grade pyriproxyfen, fipronil, and fenoxycarb were incorporated using organic solvents, whereas formulated fenoxycarb (Insegar^®) was incorporated as an aqueous suspension prior to drying and granulation. Relative to the blank samples (carrier solvents only), bait acceptance by I. purpureus was not significantly reduced (P > 0.05) by any of the treatments except 1% technical fenoxycarb. Bait acceptance by I. rufoniger gp sp. was significantly suppressed by 0.2% fipronil, but not by higher concentrations. When water was used as the carrier solvent the blank sample was significantly (P < 0.05) less attractive to I. purpureus than the untreated control, suggesting that wetting of dog food‐based baits in field situations may irreversibly reduce their attractiveness. Laboratory colonies were used in choice and no‐choice tests to assess the efficacy of dog food baits containing fipronil (0.05–0.2% w/w). The corrected mortality for I. purpureus ranged from 88 to 100% and from 90 to 97% in the no‐choice and choice tests, respectively. In no‐choice tests I. rufoniger gp sp. corrected mortality varied from 52 to 60%, but in choice tests the corrected mortality did not exceed 26%. Ground dog food containing fipronil (0.05–0.2% w/w) has the potential to provide effective control of I. purpureus in citrus orchards, but alternative toxicants or lower fipronil concentrations may be required for control of I. rufoniger gp sp.     

Age polyethism in the leaf-cutting ant Acromyrmex subterraneus brunneus Forel, 1911 (Hym., Formicidae)

Abstract  This study describes and quantifies the behavioural acts of two laboratory colonies of Acromyrmex subterraneus brunneus by investigating worker age polyethism. Twenty-nine behavioural acts were recorded during the 19-week observation period. Young individuals performed tasks inside the nest related to brood care and care for the fungus garden, whereas older individuals performed activities outside the nest such as foraging and activities in the waste chamber. The average longevity (±SD) was 108.21 ± 3.30, 109.15 ± 1.92 and 122.71 ± 1.55 days for large, medium and small workers, respectively. The small-sized workers presented a higher probability of reaching older age than large- and medium-sized workers. This study describes task switching according to age polyethism and the relationship of physical and temporal subcastes.     

Hybridization of chromosome-polymorphic populations of the inquiline ant,Doronomyrmex kutteri (Hym., Formicidae)

Summary The workerless, inquiline ant,Doronomyrmex kutteri has isolated populations with a haploid chromosome number ofn=23 both in the Alps (Swiss and South Tyrolean Alps) and in Sweden, and a population withn=25 in southern Germany. Crossbreeding of sexuals from all populations proved successful. Backcrosses of F1-females with males from the parental populations produced F2-females, and hybrid males withn=23, 24, or 25 chromosomes. The chromosome polymorphism is not due to B-chromosomes. Probably then=25 karyotype originated from then=23 karyotype by two Robertsonian fissions (2 ¯M 4 ¯A), since then=25 karyotype was found in only one of the populations. Diploid males occurred frequently in colonies from four out of five sites investigated.     

Physical resistance as a criterion in the selection of foraging material by Acromyrmex subterraneus brunneus Forel, 1911 (Hym., Formicidae)

Abstract:  Leaf-cutting ants forage on a wide variety of plant species using the physical and chemical characteristics of the plants as a selection criterion. In order to determine the influence of the physical factor on the selection of foraging material, inert materials such as floral sponge, polystyrene, plastic and clay, which possess different degrees of physical resistance to cutting, were offered simultaneously to five Acromyrmex subterraneus brunneus colonies, and assessed 12 and 24 h after foraging. No substrate selectivity was observed during foraging. Physical resistance was used as a decision criterion for the incorporation or return of the foraged material. This fact suggests the existence of a second time of selection of the foraged material inside the colony during cultivation of the symbiontic fungus.     

Qualitative aspects of myrmecocenosis (Hym., Formicidae) in olive orchards with different agricultural management in Spain

A study has been made of the presence of ants in 60 olive trees in each of three orchards under different agricultural management in the province of Granada (southern Spain), during the months of May, July and September 1997, using both observational methods as well as the collection of specimens from the soil and trunk and the tree canopy. A total of 18 species of ants were identified, 16 of which were present in the orchard of Arenales, four in Colomera 1, and nine in Colomera 2. The number of species varies over the survey, being greatest before the flowering of the trees, this period coinciding with the lowest temperatures. The species Tapinoma nigerrimum (Nylander) was the only species present in all the samplings of the olive orchards, and the other common species in the three zones proved to be: Messor barbarus (L. 1767), Tetramorium semilaeve André and Plagiolepis pygmaea (Latr.). Most of the species found made their nests in the soil under the tree canopy, and only four species nested exclusively in open areas. Ten species foraged in the tree and seven foraged in groups. The three olive orchards were similar in phenology, temperature and humidity, and therefore the differences in the myrmecofauna at the different sites were attributed to agricultural practices at each site.     

Molecular Phylogeny among Local Populations of Formica japonica (Hym., Formicidae) in Korea

ABSTRACT Not only were used Random amplified polymorphismic DNA(RAPD) markers as input for an analysis of molecular variance (AMOVA) and cluster analysis to describe the population genetic structure, but also morphometric analysis of Formica japonica in Korea in order to investigate the relationships between local populations according to altitude. The ten populations of F. japonica in Korea did not showed any relationships according to altitude in morphological analysis, while they showed distinct relationship in RAPD analysis. It was noticed that they were clearly separated as four groups according to altitude. The first was Jirisan-Gachilbong- Gyebangsan population, the second Iksansi-Odongdo, the third Deukyusan-Hallasan, the fourth Siheungsi- Seonamsa-Jinjusi. The first group was high mountainous, the second flat and low altitude, the third high mountainous, and the fourth flat and low altitude. They occur from low altitude to comparative high altitude 1,400 m in Korea. Actually, it was found that the relationships of 10 local populations of Korean Formica japonica were not related to morphological evolution, but related to molecular evolutionary data evolved from RAPD analysis.     

Vertical and horizontal movements of Fuller's rose weevil (Coleoptera: Curculionidae) in Australian citrus groves

Fuller's rose weevil (FRW; Asynonychus cervinus (Boheman)) is a pest of quarantine concern in many Asian markets for Australian citrus. We investigated vertical (tree climbing) and horizontal movements (inter‐tree movements) of FRW adults in a citrus orchard during 2009–2011 with mark‐recapture experiments. Trunk traps were used to intercept tree‐climbing adults. The results showed that the majority of the adults released on the foliage stayed in the canopy, however considerable numbers did drop and some dropped multiple times. The rate of drops appeared to be fixed, independent of how many times the weevils had dropped before. Inter‐tree movements of adults in the canopy occurred mainly within rows, probably because of touching foliage between within‐row neighboring trees. Movement directions on the ground were more random, when reliance on touching foliage was not necessary. According to fitted dispersal equations, the average dispersal distance was 38 m for weevils released on foliage and 127 m for those released on the ground. Trunk banding with chemicals is an important control tactic for FRW, and based on our results, chemicals should be applied at a high enough rate (or in a wide enough band) to ensure the weevils are killed by a single crossing. For maximum reductions of FRW populations in citrus, control actions should be applied not only to infested blocks but also to neighboring blocks in the orchard.     

Characterization of 24 microsatellite markers in 11 species of fire ants in the genus Solenopsis (Hymenoptera: Formicidae)

The social parasite ant Solenopsis daguerrei infests colonies of several mound-building fire ant species. Twenty-four microsatellite markers were isolated from a repeat-enriched genomic library of S. daguerrei. Eleven loci were polymorphic in this ant with two to six alleles per locus. Expected heterozygosity ranged from 0.0222 to 0.7940 among loci. Most microsatellites amplified successfully across the 11 Solenopsis species tested and will be useful for evolutionary genetic studies in this diverse ant group.     

The apparent establishment and subsequent eradication of the Australian giant bulldog ant Myrmecia brevinoda Forel (Hymenoptera: Formicidae) in New Zealand

Abstract

The Australian giant bulldog ant Myrmecia brevinoda Forel was first observed in New Zealand in 1940 (Keall 1981). Further observations of this species were made at a location in Devonport in 1948 and 1965, and a nest destroyed at this site in 1981. Since this time no further observations have been made, yet the status of this species is commonly listed as “uncertain establishment” on New Zealand faunal lists. We describe the control procedure used in 1981. In addition, to determine its current status we resurveyed ants in the area of earlier infestation using visual searches, pitfall trapping, and a reward for discovery posted to local residents. No evidence of M. brevinoda was found, though several other invasive species were found, including the Argentine ant Linepithema humile (Mayr), Pheidole rugosula Forel, and a recently established Australian cryptic Solenopsis species. Given the results of our survey and the absence of other reports of M. brevinoda over the last 24 years, we consider this species to be extinct or eradicated from New Zealand.     

Foraging characteristics and intraspecific behaviour of the exotic species Monomorium sydneyense (Hymenoptera: Formicidae) in New Zealand,with implications for its management

Abstract

We attempt to evaluate the biosecurity risk posed by the newly established exotic ant species Monomorium sydneyense Forel, in New Zealand. Aggression was observed between workers from different M. sydneyense nests, indicating that unicoloniality is unlikely. Nests had multiple queens, and nest foundation is apparently via winged queens. The foraging behaviour corresponded to multicoloniality, with workers foraging in close proximity to the nest. In trials during December (2003) and March (2004), workers had a >50% probability of finding food at a distance of 0.8–1 m from their nest, but on cooler study dates (October 2004) our logistic regression model indicated that they would not reach this threshold irrespective of how close the food was to the nest. Although M. sydneyense forage during both night and day, they appeared to be relatively inefficient at locating food. We conclude that under the conditions assessed here, the environmental damage likely to be caused by M. sydneyense is modest compared with other invasive ant species.     

基于线粒体COI、COII和Cyt b基因的蚁属13种的分子系统学研究（膜翅目：蚁科：蚁亚科）

以线粒体mtDNA中的COI、COII及Cyt b基因序列为分子标记,对蚁属13种进行分析研究。结果表明,蚁属线粒体基因组成具有昆虫基因的普遍特征,如有明显的A+T偏向性,A、T密码子使用频率高等特点。基于蚁属线粒体基因进行遗传距离分析,并结合构建系统发育树,结果表明蚁属内各物种间遗传距离相差较小,遗传距离值基本在0.1以内,遗传距离较远的种发生在北京凹头蚁和掘穴蚁之间,蚁属内各种间分化与形态学研究结果基本一致。     

The army ant Aenictus silvestrii and its related species in Southeast Asia,with a description of a new species (Hymenoptera: Formicidae: Aenictinae)

Three species of Aenictus with reduced numbers of antennal segments (8–9) occur in Southeast Asia: A. jarujini sp. nov., A. latifemoratus and A. silvestrii. Aenictus latifemoratus is new to Java and Borneo, while A. silvestrii is recorded for the first time from Borneo.     

Egg–larval opiine parasitoids (Hym., Braconidae) of tephritid fruit fly pests do not attack the flowerhead-feeder Trupanea dubautiae (Dipt., Tephritidae)

Abstract:  We investigated the potential impact of three opiine tephritid fruit fly parasitoids: Fopius arisanus (Sonan), Fopius caudatus (Szépligeti) and Fopius ceratitivorus Wharton, on the non-target native Hawaiian tephritid, Trupanea dubautiae (Bryan), infesting flowerheads of the endemic Asteraceae shrub Dubautia raillardioides Hillebrand. The three species are the only known opiine fruit fly parasitoids that attack host eggs (but occasionally attack first instars). F. arisanus , which originated in southeast Asia, is now widely established in Hawaii and elsewhere in the world, while the other two are African species currently in quarantine in Hawaii. In the laboratory, field-collected flowerheads of D. raillardioides containing T. dubautiae eggs and first instar larvae were exposed to naïve female wasps of each of the three Fopius species in the absence (no-choice test) or presence (choice test) of papaya fruit infested with eggs of the Mediterranean fruit fly Ceratitis capitata (Wiedemann), the parasitoids' normal host. All three Fopius species visited the papaya fruit much more often than the flowerheads, and displayed normal ovipositional responses (probing and stinging) on the fruit in the choice test. None of the three parasitoid species showed ovipositional responses to flowerheads in either choice or no-choice tests. As a result, not a single T. dubautiae egg or larva was attacked by any of the three parasitoids, indicating that these parasitoids of pest tephritids are unable to recognize the microhabitats of flowerhead-feeding tephritids. The results suggest minimal risk of non-target impact in these biological control agents.     

Histological study of the spermatheca in three thelytokous parthenogenetic ant species,Pristomyrmex punctatus,Pyramica membranifera and Monomorium triviale (Hymenoptera: Formicidae)

Gotoh, A., Billen, J., Tsuji, K., Sasaki, T. and Ito, F. 2011. Histological study of the spermatheca in three thelytokous parthenogenetic ant species, Pristomyrmex punctatus, Pyramica membranifera and Monomorium triviale (Hymenoptera: Formicidae). —Acta Zoologica (Stockholm) 00 :1–8. The evolution of obligate parthenogenesis may induce the degeneration of female mating ability and subsequently affect the morphology of the female reproductive organs related to mating and/or sperm storage. Here, we investigated the size and structure of the sperm storage organ, the spermatheca, in three thelytokous parthenogenetic myrmicine ant species, Pristomyrmex punctatus, Pyramica membranifera and Monomorium triviale, and compared it with that of their related sexually reproducing species. So far, mated individuals have never been found in these three species, which appears to be in line with their parthenogenetic status. Although the spermatheca appears to be useless in these species, we could not find any evidence on the degeneration in size and morphology of their spermathecae. The spermathecal reservoir still has the columnar hilar epithelium, which is one of the major features for a functional spermatheca in ants.     

Biological control of the cassava mealybug Phenacoccus manihoti (Hom., Pseudococcidae) by Epidinocarsis lopezi (Hym., Encyrtidae) in Malawi

From 1985 to 1989 five large scale surveys were made to document the spread of the cassava mealybug (CM) Phenacoccus manihoti Matile‐Ferrero (Hom., Pseudococcidae) and the releases and successful establishment of its exotic parasitoid Epidinocarsis lopezi (De Santis) (Hym., Encyrtidae) through most cassava‐growing areas of Malawi. In a multiple regression analysis involving 29 meteorological, agronomic and plant variables from 476 fields, the duration of E. lopezi's presence was the major factor influencing CM population densities. In the first year the CM was recorded in a particular place, 25% of all tips had more than 100 CM. Wherever E. lopezi had been present for two years or more, CM populations were reduced on average seven times and tips infested with more than 100 CM became rare (1%). In parallel, damage on cassava tips stabilized at a low level. Similarly, along Lake Malawi, 84.9% of all tips had more than 10 CM in 1986; this value stabilized at 3.3%‐4.0% in 1988–1989. Indigenous coccinellids were often abundant in the first year of the CM infestation, but their populations collapsed later, while the frequency of fields with E. lopezi increased. In 1987, farmers abandoned 28.4% of all fields where E. lopezi was just introduced as compared with 2.7% where the parasitoid had been present for two years or more. Overall, satisfactory control was achieved by E. lopezi in all but a few fields concentrated on extremely poor soils characterized by sand dune vegetation. The socioeconomic implications of this ongoing and apparently successful biological control program are discussed.     

The role of Rhytidoponera metallica (Hymenoptera,Formicidae) in facilitating post‐fire seed germination of three ant‐dispersed legume species

The fire avoidance hypothesis proposes that a benefit of seed dispersal by ants (myrmecochory) is to protect seeds from being killed during fire and to facilitate post‐fire germination of seeds that require heat shock to break their physical dormancy. The aim of this study was to quantify the effect of fire and seed burial by a predominant seed‐dispersing ant, Rhytidoponera metallica (subfamily: Ectatomminae) on germination levels of three ant‐dispersed legume species (Pultenaea daphnoides, Acacia myrtifolia and Acacia pycnantha). Experimental burial of seeds within aluminium cans at a site prior to being burnt and at an adjacent unburnt site showed that fire increased germination levels, particularly for seeds buried at 1‐ and 2‐cm deep and that overall, germination levels differed among the three plant species. To quantify seed burial depths and post‐fire germination levels facilitated by R. metallica ants, seeds were fed to colonies prior to fire at the burnt and unburnt sites. Of the seeds buried within nests that were recovered, between 45% and 75% occurred within the upper 6 cm of the soil profile, although unexpectedly, greater percentages of seeds were recovered from the upper 0–2 cm of nests in the unburnt site compared with nests in the burnt site. Germination levels of buried seeds associated with R. metallica nests ranged from 21.2% to 29.5% in the burnt site compared with 3.1–14.8% in the unburnt site. While increased seed germination levels were associated with R. metallica nests following fire, most seeds were buried at depths below those where optimal temperatures for breaking seed dormancy occurred during the fire. We suggest that R. metallica ants may provide fire avoidance benefits to myrmecochorous seeds by burying them at a range of depths within a potential germination zone defined by intra‐ and inter‐fire variation in levels of soil heating.     

Effect of different ground cover management on spider mites (Acari: Tetranychidae) and their phytoseiid (Acari: Phytoseiidae) enemies in citrus orchards

We determined the effect of ground cover on phytoseiid predatory mite populations and the potential biological control of Panonychus citri (McGregor). Results showed that citrus trees with ground cover contained higher population densities of predatory mites and provided better regulation of P. citri than trees in bare soil. The ground cover Ageratum conyzoides L. performed better than Palspalum notatum Flugge in sheltering phytoseiid mites.     

Influence of ants (Hymenoptera: Formicidae) on honeydew excretion and escape behaviors in a myrmecophile,dalbulus quinquenotatus (Homoptera: Cicadellidae), and its congeners

Few leafhopper species are known to be ant-attended. Evidence is presented that unequivocally demonstrates that Dalbulus quinquenotatusis a myrmecophile. In a greenhouse study, the behavior of D. quinquenotatusand four Dalbulusspecies not associated with ants was observed in the absence and presence of the pavement ant, Tetramorium caespitum. D. quinquenotatusis readily contacted by tending ants and responds to stroking on the abdomen from ants' antennae by excreting and holding honeydew droplets until droplets are removed by ants. Nonattended Dalbulusspecies avoid contact with ants by walking,jumping, or flying away when approached. D. quinquenotatusexcretes three to six times the volume of honeydew as do two nonattended species, D. maidisand D. gelbus.Droplets of D. quinquenotatusare about 23% larger in diameter and excreted two to four times more frequently than for the other species. D. quinquenotatustakes about 0.15 s to form honeydew droplets on the anal tube, then holds the droplet an average of 0.28 s before expelling it when ants are absent. In the presence of ants, D. quinquenotatusholds the droplet an average of 1.31 s, which gives ants time to harvest the droplet. Nonattended species, however, immediately expel droplets from the anal tube after droplet formation. This ant-leafhopper mutualism apparently has evolved due to the ability of D. quinquenotatusto have extensive physical contact with ants and excrete large amounts of honeydew. D. chiapensis,a possible descendent of D. quinquenotatus,may secondarily have lost its mutualistic relationship with ants.     

Isolation and characterization of microsatellite loci in the plant-ant Pseudomyrmex ferrugineus (Formicidae: Pseudomyrmecinae) and cross-testing for two congeneric species

To investigate the population structure of the obligate plant-ant Pseudomyrmex ferrugineus, we developed primers for 12 microsatellite loci. We tested the variability of the markers on 11 individuals from each of two populations (totalling 22 individuals) and found two to 12 alleles per locus and population. No deviations from Hardy-Weinberg equilibrium were detected. Observed and expected heterozygosities at each locus ranged from 0.00 to 0.50 and from 0.08 to 0.46, respectively. We also investigated suitability of these primers in two congeneric species.