DNA sequence variation in the ITS-1 rDNA subunit and host relationships in sorghum midge, Stenodiplosis sorghicola (Coquillett) (Diptera: Cecidomyiidae), in Australia

Sequence variation in the internal transcribed spacer (ITS-1) ribosomal DNA subunit was examined for sorghum midge obtained from introduced and native hosts in south-eastern and central Queensland. No variation was observed relative to host plant or geographical distance for midges collected from two introduced hosts, grain sorghum ( Sorghum bicolor ) and Johnson grass ( S. halepense ); however, sequence differences were observed between midges from introduced and native hosts and among midges from a single native host, slender bluegrass ( Dichanthium affine ). No evidence was observed of introduced midges on native hosts, or vice versa. These results agree with previously hypothesised host distributions for native and introduced midges in Australia, and expand the sample of introduced hosts to include Johnson grass. They suggest that Stenodiplosis sorghicola , the principal midge infesting grain sorghum, is also the most common species on Johnson grass. This confirms that Johnson grass plays a role in the population dynamics of S. sorghicola and suggests that midges originating from Johnson grass may influence levels of infestation in grain sorghum.     

Effect of soil burial depth and wetting on mortality of diapausing larvae and patterns of post-diapause adult emergence of sorghum midge, Stenodiplosis sorghicola (Coquillett) (Diptera: Cecidomyiidae)

Abstract  In south-eastern Queensland, Australia, sorghum planted in early spring usually escapes sorghum midge, Stenodiplosis sorghicola , attack. Experiments were conducted to better understand the role of winter diapause in the population dynamics of this pest. Emergence patterns of adult midge from diapausing larvae on the soil surface and at various depths were investigated during spring to autumn of 1987/88–1989/90. From 1987/88 to 1989/90, 89%, 65% and 98% of adult emergence, respectively, occurred during November and December. Adult emergence from larvae diapausing on the soil surface was severely reduced due to high mortality attributed to surface soil temperatures in excess of 40°C, with much of this mortality occurring between mid-September and mid-October. Emergence of adults from the soil surface was considerably delayed in the 1988/89 season compared with larvae buried at 5 or 10 cm which had similar emergence patterns for all three seasons. In 1989/90, when a 1-cm-deep treatment was included, there was a 392% increase in adult emergence from this treatment compared with deeper treatments. Some diapausing larvae on the surface did not emerge at the end of summer in only 1 year (1989/90), when 28.0% of the larvae on the surface remained in diapause, whereas only 0.8% of the buried larvae remained in diapause. We conclude that the pattern of emergence explains why spring plantings of sorghum in south-eastern Queensland usually escape sorghum midge attack.     

Host-plant preference and oviposition responses of the sorghum midge, Stenodiplosis sorghicola (Coquillett) (Dipt., Cecidomyiidae) towards wild relatives of sorghum

Sorghum midge, Stenodiplosis ( Contarinia ) sorghicola (Coquillett) is an important pest of grain sorghum world-wide. Considerable progress has been made in screening and breeding for resistance to sorghum midge. However, some of the sources of resistance have become susceptible to sorghum midge in Kenya, in eastern Africa. Therefore, the wild relatives of Sorghum bicolor were studied as a possible source of new genes conferring resistance to sorghum midge. Midge females did not lay eggs in the spikelets of Sorghum amplum , Sorghum bulbosum , and Sorghum angustum compared to 30% spikelets with eggs in Sorghum halepense when infested with five midge females per panicle under no-choice conditions. However, one egg was laid in S. amplum when infested with 50 midges per panicle. A larger number of midges were attracted to the odours from the panicles of S. halepense than to the panicles of Sorghum stipoideum , Sorghum brachypodum , S. angustum , Sorghum macrospermum , Sorghum nitidium , Sorghum laxiflorum , and S. amplum in dual-choice olfactometer tests. The differences in midge response to the odours from S. halepense and Sorghum intrans were not significant. Under multi-choice conditions, when the females were also allowed a contact with the host, more sorghum midge females were attracted to the panicles of S. bicolor compared with S. amplum , S. angustum , and S. halepense . In another test, numerically more midges responded to the panicles of IS 10712 compared with S. halepense , whereas the differences in midge response to the panicles of ICSV 197 ( S. bicolor ) and S. halepense were not apparent, indicating that S. halepense is as attractive to sorghum midge females as S. bicolor . The wild relatives of sorghum (except S. halepense ) were not preferred for oviposition, and they were also less attractive to the sorghum midge females. Thus, wild relatives of sorghum can prove to be an alternative source of genes for resistance to sorghum midge.     

Effect of sorghum resistant to Stenodiplosis sorghicola (Coquillett) (Diptera: Cecidomyiidae) on oviposition and development of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae)

Abstract Helicoverpa armigera oviposition preference for, and larval development on sorghum hybrids with differing resistance to sorghum midge, Stenodiplosis sorghicola , were investigated. When H. armigera larvae were fed seed of resistant and susceptible hybrids in the laboratory there were no differences in larval and pupal sizes or the rate of development. The same result was recorded when larvae fed on panicles on plants in a glasshouse. On some sampling occasions, significantly more eggs were laid on panicles of resistant hybrids in the field. This occurred when plants were in plots and also in a mixed planting. Midge-resistance status did not affect levels of egg parasitism. In a field study using recombinant inbred lines between a midge-resistant and a midge-susceptible line, no relationship was found between level of resistance and oviposition of H. armigera . We conclude that, although midge-resistant hybrids are sometimes preferred for oviposition by H. armigera, the resistance per se does not determine this preference. Egg survival, larval survival, development and resultant damage are not significantly affected by the midge-resistance status of the host.     

Antixenosis component of resistance to sorghum midge, Contarinia sorghicola Coq. in Sorghum bicolor (L.) Moench

Sorghum midge, Contarinia sorghicola Coq. (Diptera: Cecidomyiidae) is the most destructive pest of grain sorghum, and host-plant resistance is an effective method of controlling this insect. We studied the antixenosis component of resistance to sorghum midge using multi-, double- and no-choice cage tests, and under multi-choice field conditions to quantify and understand the nature of antixenosis component of resistance to this insect in Sorghum bicolor (L.) Moench. Midge response towards sorghum panicles was influenced by panicle size and cage type used to study the orientation behaviour. Maximum number of midges were recorded at 30 and 60 min after initiating the experiment. Antixenosis shown by C. sorghicola under multi-choice field conditions to ICSV 197 and TAM 2566 was not confirmed under cage tests, while DJ 6514, AF 28 and IS 3461 were non-preferred both under field and cage conditions. Midge-resistant female parents (PM 7061 and PM 7068) were less preferred than the midge susceptible (ICSA 42 and 296A) female parents. Male-sterility did not influence host finding and acceptance by the midge females, although in one out of two tests, the maintainer lines (B-lines) were preferred over the male-sterile lines (A-lines).     

Direct and indirect effects of egg parasitism by Neopolycystus Girault sp. (Hymenoptera: Pteromalidae) on Paropsis atomaria Olivier (Coleoptera: Chrysomelidae)

Abstract  Neopolycystus sp. is the only primary egg parasitoid associated with the pest beetle Paropsis atomaria in subtropical eucalypt plantations, but its impact on its host populations is unknown. The simplified ecosystem represented by the plantation habitat, lack of interspecific competition for host and parasitoid, and the multivoltinism of the host population makes this an ideal system for quantifying the direct and indirect effects of egg parasitism, and hence, effects on host population dynamics. Within-, between- and overall-egg-batch parasitism rates were determined at three field sites over two field seasons, and up to seven host generations. The effect of exposure time (egg batch age), host density proximity to native forest and water sources on egg parasitism rates was also tested. Neopolycystus sp. exerts a significant influence on P. atomaria populations in Eucalyptus cloeziana. plantations in south-eastern Queensland, causing the direct (13%) and indirect (15%) mortality of almost one-third of all eggs in the field. Across seasons and generations, 45% of egg batches were parasitised, with a within-batch parasitism rate of around 30%. Between-batch parasitism increased up to 5–6 days after oviposition in the field, although within-batch parasitism rates generally did not. However, there were few apparent patterns to egg parasitism, with rates often varying significantly between sites and seasons.     

Conservation genetics and species status of an endangered Australian dragon, <Emphasis Type="Italic">Tympanocryptis pinguicolla</Emphasis> (Reptilia: Agamidae)

We present a phylogenetic and morphological study of the grassland earless dragon, Tympanocryptis pinguicolla, an endangered habitat specialist that occurs in a few isolated populations in eastern Australia. Tympanocryptis pinguicolla occurred historically in Victoria in south-eastern Australia, but has not been seen since 1990, and current populations are known in New South Wales and Canberra in south-eastern Australia. Recently, new populations identified as T. pinguicolla were discovered on the Darling Downs, Queensland. Translocation of individuals between these populations has been suggested as a conservation management strategy to maintain genetic diversity. To address this issue, we undertook a phylogenetic study of all major populations of T. pinguicolla using a 1838 bp region of mitochondrial DNA, incorporating ND1, ND2, COI and eight tRNA genes. We incorporated specialized degraded-DNA techniques to amplify DNA from historical museum specimens, as no extant tissue was available for Victorian populations. Our results, which include morphological analysis, provide convincing evidence that populations currently identified as T.␣pinguicolla do not comprise a monophyletic species, as the populations from the Darling Downs are more closely related to T. tetraporophora than to T. pinguicolla. In addition, we find that there is a significant level of haplotype divergence between populations of T. pinguicolla, indicating that these lineages separated at least 1.5 mya. Our results suggest translocation may not be an appropriate management strategy and our findings that Darling Downs populations are not T.␣pinguicolla will significantly influence the conservation management of this species in Queensland.     

Effect of insecticide application and host plant resistance on parasitization of sorghum midge,Contarinia sorghicola coq.

Sorghum midge (Contarinia sorghicola Coq.) (Diptera: Cecidomyiidae) is one of the most important pests of grain sorghum. The effects of different insecticides applied at the complete‐an‐thesis stage for insect control, and host plant resistance on the parasitization of sorghum midge, were studied. Tetrastichus spp. and Eupelmus popa are the major parasites of sorghum midge larvae. Of the several insecticides tested, monocrotophos reduced midge parasitization by half compared with the untreated control. Midge parasitization was lower on midge‐resistant genotypes. Amongst the lines resistant to sorghum midge, the levels of parasitization were higher on the moderately resistant lines IS 10132 and PM 9760 compared to those on IS 3461, IS 7005, IS 9807, IS 19512 and AF 28, etc. Parasite activity closely followed the midge population density across sowing dates. The role of these factors on the effectiveness of midge parasites in integrated pest management are discussed.     

Evaluation of planting date, sorghum hybrid, and insecticide treatment on sorghum midge (Diptera: Cecidomyiidae) management in northeast Louisiana

The combined effect of planting date, insecticide treatment, and host-plant resistance was studied in northeast Louisiana for management of the sorghum midge, Stenodiplosis sorghicola (Coquillett), during 1994 and 1995. Significantly higher numbers of sorghum midges were observed visiting flowering spikelets of the midge-susceptible sorghum hybrid (Delta and Pine Land 'DP1552') than those of the midge-resistant sorghum hybrid (DeKalb 'DK-60'). Numbers of midges averaged 1.2 and 0.6 per flowering panicle in the susceptible and resistant sorghum hybrids, respectively, in 1994 and 1.8 and 1.0, respectively, in 1995. Midge densities increased significantly as the sorghum flowering season progressed. Sorghum midge reached peak densities during the first half of August in 1994 and 1995. The length of the flowering period in the early-planted (mid-March) sorghum was significantly longer compared with the flowering periods in the mid-April, mid-May, or mid-June planted sorghums. This resulted in prolonged exposure of flowering panicles to ovipositing midges and increased midge damage in the early-planted (mid-March) sorghum. Damage by sorghum midge was significantly higher in the early-planted (mid-March) sorghum hybrids than in the late-planted (mid-June) sorghum hybrids. The midge-susceptible hybrid produced highest yields when planted in mid-April and mid-May (optimum period) and lower yields when planted very early (i.e., mid-March) or late (i.e., mid-June). No significant differences were observed in yields for the resistant hybrid at any planting date in 1994. However, in 1995, significantly lower yields were recorded in resistant sorghum planted in mid-June. Levels of sorghum midge damage and sorghum seed yields in the untreated resistant hybrid were not significantly different than those observed in the insecticide-treated susceptible hybrid. Numbers of adult midges captured on sticky traps were positively correlated to numbers of visual estimates of ovipositing midge females visiting flowering spikelets.     

Parasitism ofPhthorimaea operculella [Lep.: Gelechiidae] larvae in Queensland

Parasitism ofPhthorimaea operculella (Zeller) larvae on potato foliage was examined intensively in the Lockyer Valley, south-eastern Queensland from 1975–78 and extensively from other hosts and areas of Queensland. The % parasitism in the Lockyer Valley exceeded 50% in 29 of the 36 collections. The parasite species were dominated by the introducedCopidosoma desantisi Annecke & Mynhardt (Encyrtidae) andOrgilus lepidus Muesebeck (Braconidae) which together accounted for 92.6% of parasite numbers recorded. In more northern areas of Queensland, the dominant parasite species found was the introducedApanteles subandinus Blanchard (Braconidae). Other hymenopterous parasites found wereMicrochelonus curvimaculatus Cameron (Braconidae), Elasmus funereus Riek (Elasmidae) andTemelucha minuta (Morley) (Ichneumonidae).     

Multiple host use by the egg parasitoid Trissolcus basalis (Wollaston) in a soybean agricultural system: biological control and environmental implications

1 Species of bugs (Hemiptera: Pentatomidae and other families) that are parasitized by the egg parasitoid Trissolcus basalis (Wollaston) (Hymenoptera: Scelionidae) in the soybean agricultural system on the Darling Downs in south-eastern Queensland, Australia, are reported. The degree to which eggs of each bug species are used by T. basalis is quantified, which allows assessment of the role of these alternative host species in the biological control of the green vegetable bug Nezara viridula (L.). 2 Egg masses of nine species of pentatomid bugs and one unidentified bug species were collected. Parasitism rates of egg masses of all species averaged 50–70% but were significantly lower for the more important pest species, including the green vegetable bug, than for some of the agriculturally less important species. 3 Trissolcus basalis emerged from nearly all species collected and was the major parasitoid to emerge from most species. A number of native species were parasitized heavily by T. basalis and parasitism of such species may enhance biological control of the green vegetable bug, but may also pose environmental concerns. Parasitism of predatory bugs by T. basalis may have a negative impact on the biological control of other pests, especially lepidopterous pests. 4 Although the impact of T. basalis on native and predatory host species was not directly quantified, these host species remain abundant and therefore do not appear to be affected adversely by such high rates of parasitism.     

四倍体高粱与约翰逊草间的亲缘关系分析

本研究以四倍体高粱与约翰逊草为材料,利用SSR分子标记和细胞遗传学方法分析了高粱与约翰逊草间的亲缘关系,SSR分析结果表明,高粱与约翰逊草的遗传背景差异较大,SSR差异位点和相似位点在连锁群上的分布具不平衡性;按照差异引物出现频率高低,将连锁群分为两类：高度差异区和低度差异区。细胞学分析结果表明：（1）双亲及杂交种都是不规则的四倍体遗传群体。（2）花粉母细胞减数分裂中期I,双亲及杂交种染色体配对以二价体和四价体为主,杂交种平均每个细胞二价体数为17．00,四倍体高粱为15．23、约翰逊草为15．83,四价体数分别为0．95,2．15和1．60个。但杂交种减数分裂过程中也出现一定数量的单价体,减数分裂会形成一定比例的非整倍配子。SSR检测结果与细胞学分析结果具有一致性,约翰逊草与高粱的染色体组间存在一定程度的同源性。二者杂交不能形成稳定遗传的双二倍体。     

Distribution and phenology of Dasineura oxycoccana (Diptera: Cecidomyiidae) in Michigan blueberries

The blueberry gall midge, Dasineura oxycoccana Johnson, is a serious pest of rabbiteye blueberries in Florida, Georgia, and Mississippi, and a potential pest of southern and northern highbush blueberries. Its damage has been observed with increasing frequency in highbush blueberry plantings in the Great Lakes region, including in Wisconsin and in Michigan. Unlike in rabbiteye blueberry plantings, where blueberry gall midge primarily damages flowering buds, it is found to damage only the vegetative shoots of northern highbush blueberry. In this study, farms throughout Michigan were surveyed for the presence of blueberry gall midge and it was found in 43 of 46 sampled farms in 11 counties. From 2009-2011, several monitoring techniques, including yellow sticky traps, emergence traps, observational sampling, and vegetative shoot dissections were used to determine the ecology of this species in blueberry fields in southwest Michigan. Emergence traps were most useful in early detection of blueberry gall midge in April, and observational sampling for damage symptoms and vegetative shoot dissections revealed multiple population peaks throughout July and August. Infestation was detected in vegetative shoot tips in all parts of the bushes, with initial infestation greatest at the base of bushes. Degree day accumulations until first midge detection and peak infestation suggest some potential for predicting key events in the pest's phenology. This information about the distribution and timing of infestation will be useful in developing management strategies for blueberry gall midge infestation.     

Crop-to-weed introgression has impacted allelic composition of johnsongrass populations with and without recent exposure to cultivated sorghum

Sorghum halepense L. (johnsongrass) is one of the world's most noxious weeds, and a paradigm for the potential dangers of crop-weed hybridization. Introduced into the southeastern United States about 200 years ago, S. halepense is a close relative of cultivated sorghum (Sorghum bicolor). Both artificial crossing and experimental field studies have demonstrated the potential for S. halepensex S. bicolor hybrid formation, but no prior study has addressed the long-term persistence of sorghum genes in johnsongrass populations. We surveyed 283 loci (on all 10 sorghum linkage groups) to identify 77 alleles at 69 loci that are found in US sorghum cultivars but are absent from a worldwide sampling of johnsongrass genotypes. These putatively cultivar-specific alleles were present in up to 32.3% of individuals in johnsongrass populations adjacent to long-term sorghum production fields in Texas and Nebraska. Lower frequencies of cultivar-specific alleles at smaller numbers of loci are found in johnsongrass populations from New Jersey and Georgia with no recent exposure to cultivated sorghum, suggesting that introgressed sorghum alleles may be dispersed across long distances. The number of cultivar-specific alleles and extensive multilocus patterns of cultivar-specific allelic composition observed at both linked and unlinked loci in the johnsongrass populations, are inconsistent with alternatives to introgression such as convergence, or joint retention of ancestral polymorphisms. Naturalized johnsongrass populations appear to provide a conduit by which transgenes from sorghum could become widely disseminated.     

Emergence Pattern of Sorghum Midge and its Major Parasitoids on Midge-resistant and Susceptible Genotypes

Studies were conducted on the species composition of parasitoids of sorghum midge, Stenodiplosis sorghicola Coquillett (Diptera: Cecidomyiidae), emergence pattern and level of parasitism. They took place at the International Crops Research Institute for the Semi-Arid Tropics Asia Centre using three midge-resistant (ICSV 745, ICSV 89058 and IS 10712) and three susceptible (Swarna, CSH 9 and ICSV 112) genotypes during the 1992-93 post-rainy and 1993 rainy seasons. The species of parasitoids collected were Aprostocetus gala Walker, A. coimbatorensis Rohwer (Hymenoptera: Eulophidae) and Eupelmus spp. (Hymenoptera: Eupelmidae). The species composition varied with the season, but was unaffected by varietal resistance and susceptibility to the midge. Although both species of Aprostocetus were present in rainy and post-rainy seasons, A. gala was predominant during the rainy season whereas A. coimbatorensis was predominant in the post-rainy season. There was no significant difference in the pattern of parasitoid emergence or the level of midge parasitization between resistant and susceptible genotypes. These results indicate that resistance to midge in the genotypes studied was not antagonistic to parasitoid activity, and that there is potential to interface biological control with host-plant resistance in the management of this insect.     

Spread and potential distribution of Senecio madagascariensis Poir. (fireweed) in Australia

Abstract The potential distribution of the herbaceous weed Senecio madagascariensis Poir. (fireweed) in Australia was estimated using the Bioclimate Prediction System, BIOCLIM. Climate profiles for S. madagascariensis predicted that suitable areas occurred only in the south-eastern region of Australia. Its potential to spread outside these areas was assessed by comparing the present African and South American distributions of this species with that observed in Australia. The rate of spread of S. madagascariensis in New South Wales was exponential, although in some regions, such as the Gloucester River Valley, the rates had decreased because all farms had become infested. The results indicate that S. madagascariensis may spread and increase in abundance along the far south coast of New South Wales and in south-eastern Queensland. Coastal areas in eastern Victoria and as far north in Queensland as the Tropic of Capricorn may be invaded.     

Differences in egg parasitism of Chrysophtharta agricola (Chapuis) (Coleoptera: Chrysomelidae) by Enoggera nassaui Girault (Hymenoptera: Pteromalidae) in relation to host and parasitoid origin

Abstract The first instances of egg parasitism of Chrysophtharta agricola , a pest of eucalypt plantations, are recorded. Enoggera nassaui was found parasitising C. agricola egg batches in Tasmania, the Australian Capital Territory (ACT), New South Wales and Victoria: this is the first record of this parasitoid species from Victoria. One instance of Neopolycystus sp. parasitising C. agricola eggs in Victoria was also recorded. Parasitism of egg batches by E. nassaui ranged from 0 to 55% between five geographical populations collected in mainland Australia ( n  = 45), and from 0 to 2% between two populations collected in Tasmania ( n  = 300). For mainland sites at which parasitism was recorded, parasitism rates within sites differed significantly from either population in Tasmania. Reciprocal exposure experiments using one Tasmanian (Florentine Valley) and one parasitised mainland (Picadilly Circus, ACT) population were conducted in the laboratory to examine whether these different parasitism rates were attributable to egg or parasitoid origin. Parasitoids from the ACT parasitised C. agricola eggs of both origins more successfully than parasitoids from Tasmania, with up to 65% wasp emergence compared with 33% from Tasmania. Parasitoid origin significantly affected the number of wasps that emerged from exposed batches, but not the total loss from parasitism.     

Factors influencing oviposition behaviour of the sorghum midge, Contarinia sorghicola Coq.

Visual stimuli influence the orientation behaviour of the sorghum midge, Contarinia sorghicola Coq. (Diptera: Cecidomyiidae). Yellow, red and white colours are attractive to the midge while blue and black are least attractive. Sorghum panicles covered with blue- or black-coloured bags in a headcage showed maximum midge damage, while the reverse was true for panicles covered with yellow, red, and white coloured bags.
Panicles at half-anthesis with viable pollen and receptive stigmata suffered higher damage than those at the pre- and post-anthesis. Physical removal of anthers and stigmata significantly reduced the oviposition by the sorghum midge. Reduced oviposition/adult emergence was also recorded in male sterile sorghum lines (2219A and 296A) or through chemically- (Ethrel) (2-Chloro ethyl-phosphonic acid) induced male sterility in panicles of the sorghum cultivar, Swarna. Chemical stimuli from viable pollen and receptive stigmata and to a limited extent physical stimuli, govern the oviposition behaviour of the sorghum midge.
Sorghum cultivars IS 12573C, S-GIRL-MR1 and IS 2816C showed antixenosis to adult midges. However, these cultivars became susceptible under no-choice conditions in the headcage. DJ 6514 and IS 12666C were attractive to the adult midges, but showed antixenosis to oviposition under natural and no-choice conditions. Genotypes with short florets showed antixenosis for oviposition. Ovary and anther breadth and tannin content of grain showed negative associations with oviposition. Cultivar antixenosis to adult midges and oviposition is an important component of resistance to the sorghum midge.     

The Role of Integrative Taxonomy in the Conservation Management of Cryptic Species: The Taxonomic Status of Endangered Earless Dragons (Agamidae: Tympanocryptis) in the Grasslands of Queensland,Australia

Molecular phylogenetics is increasingly highlighting the prevalence of cryptic species, where morphologically similar organisms have long independent evolutionary histories. When such cryptic species are known to be declining in numbers and are at risk of extinction due to a range of threatening processes, the disjunction between molecular systematics research and conservation policy becomes a significant problem. We investigate the taxonomic status of Tympanocryptis populations in Queensland, which have previously been assigned to T. tetraporophora, using three species delimitation approaches. The taxonomic uncertainties in this species-group are of particular importance in the Darling Downs Earless Dragon (T. cf. tetraporophora), which is ranked as an endangered ‘species’ of high priority for conservation by the Queensland Department of Environment and Heritage Protection. We undertook a morphological study, integrated with a comprehensive genetic study and species delimitation analyses, to investigate the species status of populations in the region. Phylogenetic analyses of two gene regions (mtDNA: ND2; nuclear: RAG1) revealed high levels of genetic divergence between populations, indicating isolation over long evolutionary time frames, and strongly supporting two independent evolutionary lineages in southeastern Queensland, from the Darling Downs, and a third in the Gulf Region of northern Queensland. Of the three species delimitation protocols used, we found integrative taxonomy the most applicable to this cryptic species complex. Our study demonstrates the utility of integrative taxonomy as a species delimitation approach in cryptic complexes of species with conservation significance, where limited numbers of specimens are available.     

Dispersal and foraging behaviour of Platygaster californica: hosts can't run, but they can hide

Abstract.  1. Host–parasitoid models often identify foraging behaviour and dispersal distance as important for system persistence.
2. Laboratory observations and field trials were used to characterise foraging behaviour and dispersal capability of Platygaster californica Ashmead (Platygasteridae), a parasitoid of the gall midge Rhopalomyia californica Felt (Cecidomyiidae).
3. Although foraging parasitoids meticulously searched plants in laboratory observations, none of the laboratory trials resulted in 100% parasitism, and the proportion of parasitism declined as midge egg density increased.
4. The field trials showed that the distribution of parasitism over distance from a central release point was hump-shaped, as predicted by a simple diffusion model. Mean parasitoid dispersal distance was 4.5 m, considerably farther than the 1.7 m mean midge dispersal found in previous work.
5. Although the parasitoid appears to search thoroughly for midge eggs and to disperse farther than the midge, the results of this study show how this host–parasitoid system may persist due to spatially variable incomplete parasitism.