Immature stages of the bee fly Ligyra satyrus (F.) (Diptera: Bombyliidae): A hyperparasitoid of canegrubs (Coleoptera: Scarabaeidae)

We describe the third- and fourth-instar larva, pupa and biology of the hyperparasitoid bee fly Ligyra satyrus (Fabricius). The larval and pupal morphology of the bee fly is typical for members of the subfamily Anthracinae. The bee fly larvae are found inside cocoons of the scoliid Campsomeris tasmaniensis Saussure, an external parasite of canegrubs (Coleoptera: Scarabaeidae) in sugarcane fields at Ayr and Bundaberg, Queensland. Ligyra satyrus has been recorded attacking only C. tasmaniensis . Ligyra and its relatives are all parasites of predatory and parasitic, ground-nesting aculeate Hymenoptera such as Sphecidae, Pompilidae, Tiphiidae and Scoliidae. Larval morphology of the hyperparasite is similar to other ectoparasitic Bombyliidae and pupal morphology is compared to that of species in the same and related subfamilies. Rates of hyperparasitism at Gordonvale reported in the early 1900s are relatively high, but our results show that currently they are very low at Ayr and Bundaberg. These results suggest that the impact of the bee fly on natural control of the canegrubs by scoliids varies considerably.     

Parasitism of Neotropical Tiger Beetles (Coleoptera: Carabidae: Cicindelinae) by Anthrax (Diptera: Bombyliidae)

Bee flies (Bombyliidae) were recorded as parasitoids of larval tiger beetles at two rain forest localities (near São Paulo and Manaus) in Brazil. Anthrax gideon was reared from larvae of Oxycheila tristis. Up to 33 parasitoid larvae were found on a single tiger beetle host. Pupation of the bee fly took place in late August and the pupal stage lasted 14 days. The host digs horizontal burrows in contrast to the great majority of cicindelids, as does Pseudoxycheila tarsalis, the other known host of A. gideon. Two pupae of another undetermined Anthrax species were reared from larvae of Pentacomia ventralis in Central Amazonia. Pupation of this Anthrax sp. took place in October, the period of lowest host abundance.     

Competitive Superiority of Early Acting Species: A Case Study of Opiine Fruit Fly Parasitoids

Koinobiont parasitoids that attack an early host stage may have an advantage in suppressing competing parasitoids that attack later stages of the same host. We examined the competitive interaction between the two most important parasitoids of tephritid fruit flies in Hawaii, Fopius arisanus (Sonan), and Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Braconidae). The former species attacks host eggs while the latter attacks host larvae, and both species emerge as adults from the host puparia. F. arisanus physiologically suppressed egg development of D. longicaudata. Over 90% of D. longicaudata eggs died in the presence of F. arisanus larvae within host larvae of either the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) or the oriental fruit fly, Bactrocera dorsalis (Hendel). D. longicaudata appeared not to discriminate against hosts previously parasitized by F. arisanus. The mechanism that F. arisanus uses to eliminate D. longicaudata is similar to that which it employs to eliminate five other larval fruit fly parasitoids so far reported in Hawaii. This suggests that there is a broad competitive superiority of the early acting species in fruit fly parasitoids. We discuss the implication of this in relation to future biological control introductions against tephritid fruit flies.     

Phylogeny,classification and biogeography of bombyliine bee flies (Diptera,Bombyliidae)

The Bombyliinae comprises over 1100 described species in 73 known genera distributed worldwide. It is one of the largest subfamilies of bee flies (Diptera: Bombyliidae). We present the first phylogenetic hypothesis for this subfamily, based on 157 adult morphological characters scored for 123 species representing 60 genera, including all the tribes of Bombyliinae, and the related subfamilies Lordotinae and Toxophorinae. Four most parsimonious trees were generated from our analysis under equal weighting schemes. The monophyly of Bombyliinae is supported, and Lordotinae is sister to the Bombyliinae. Within Bombyliinae, Conophorini is sister to the remaining tribes. Five previously recognized tribes are revised and four new tribes are erected. We placed almost all genera in our tribal classification, based on our phylogenetic results and available character evidence. The genus Parabombylius is proposed as a synonym of Bombylius. The Gondwanan origin for the major lineages of Bombyliinae is strongly indicated by our biogeographic analysis which reconstructs ancestral areas. This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub: 1EC5C827‐34D5‐4A95‐BA78‐4ACF457F6D40.     

The spatio-temporal distribution dynamics of the cabbage seedpod weevil, Ceutorhynchus obstrictus (Coleoptera: Curculionidae), and its larval parasitoids in canola in western Canada

Distribution patterns of the cabbage seedpod weevil, Ceutorhynchus obstrictus (Marsham) (Coleoptera: Curculionidae), and its larval parasitoids were investigated in commercial fields of spring canola (Brassica rapa L. and Brassica napus L.) in southern Alberta, Canada, from 2002 to 2004 in relation to developmental stages of its host plants. Adult weevils invaded fields along one or more fronts when crops were in bud to early flower. Significant clustering of adults along field edges in early stages of invasion was followed by more homogeneous distributions as canola reached the mid to late flowering and pod enlargement stages. Larval weevil distributions, as indicated by exit holes in siliques at the end of the season, were often aligned spatially with adult distributions, but they did not coincide in all regions of the fields. The primary ectoparasitoid species attacking weevil larvae comprised Necremnus tidius (Walker) (Hymenoptera: Eulophidae), and Trichomalus lucidus (Walker), Chlorocytus sp., and Pteromalus sp. (Hymenoptera: Pteromalidae). Parasitism rates increased from 0.1 to 5.0% over the three years of study. Parasitoid distributions were often, but not consistently, spatially associated with high densities of C. obstrictus larvae. Lack of close spatial alignment of parasitoids and their hosts probably reflects low parasitoid numbers in comparison with an abundant resource of weevil larvae, and a lack of co-evolutionary history between host and parasitoids. Some parasitoids invaded fields early in host plant development, at the same time that weevils invaded. Unfortunately the synchronous invasions of host and parasitoids indicate that insecticidal applications to reduce adult weevil infestations may be detrimental to these beneficial species.     

Effect of entomopoxvirus infection of the smaller tea tortrix, Adoxophyes sp. on the development of the endoparasitoid, Ascogaster reticulatus

Infection of Adoxophyes sp. (Lepidoptera: Tortricidae) larvae by an entomopoxvirus (AsEPV) adversely affected the development of the endoparasitoid, Ascogaster reticulatus Watanabe (Hymenoptera: Braconidae). Parasitoid larvae developing in AsEPV-infected hosts grew more slowly and spent more time in their hosts than did parasitoid larvae developing in noninfected hosts. Percentages of emergence of larval parasitoids that developed in AsEPV-infected hosts were significantly lower than those of parasitoids that developed in noninfected hosts. Parasitoid larvae in AsEPV-infected host perished when their hosts died of AsEPV infection. Significant numbers of parasitized and infected larvae exhibited apolysis to the final instar, whereas noninfected-parasitized larvae died in the penultimate instars due to emergence of parasitoids.     

广大腿小蜂对菜粉蝶蛹体型大小的产卵选择及后代发育表现

产卵选择与后代发育适合度之间的相关性是进化生态学的主要科学问题之一。为探究广大腿小蜂(Brachymeria lasus)对不同体型大小寄主的选择和后代发育表现的关系,采用饥饿方法处理4龄菜粉蝶(Pieris rapae)幼虫以获得体型大小(用体质量表示)差异较大的寄主蛹,供寄生蜂选择寄生。结果表明,广大腿小蜂显著偏好体型较大的寄主蛹,而且在体型较大的蛹内产雌性后代的概率更大;子代蜂体型大小与寄主蛹大小存在显著的正相关性,但子代蜂发育历期与寄主蛹大小无相关性。研究说明,广大腿小蜂对菜粉蝶蛹的寄生选择与后代发育表现,符合寄主大小-质量模型的预测。     

Effects of learning experience on behaviour of the generalist parasitoid Sclerodermus pupariae to novel hosts

Massicus raddei Blessig (Coleoptera: Cerambycidae), also referred to as the oak long‐horned beetle (OLB), is a non‐natural host for the generalist parasitoid Sclerodermus pupariae Yang et Yao (Hymenoptera: Bethylidae). To determine whether this generalist parasitoid might be a suitable agent for the control of OLB, the adaptive learning experience of adult female parasitoids to OLB larvae was investigated in the laboratory. A Y‐tube olfactometer bioassay was used to examine the effects of adaptive learning experience on the foraging ability of parasitoids for OLB larvae. The results indicated that parasitoids were significantly attracted by the volatiles of ash bark, Fraxinus velutina, with emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) larvae and larval frass, after exposure to ash bark mixed with EAB larval frass (learning condition A). In contrast, after exposure to oak bark, Quercus liaotungensis, mixed with OLB larval frass (learning condition C), parasitoids showed significant preference for the volatiles of oak bark with OLB larvae and larval frass. On the basis of the results of no‐choice tests, we found that parasitoids exposed to learning condition C had greater paralysis efficiency and higher OLB larvae parasitism rates than those exposed to learning condition A or no experience. Furthermore, parasitoids fed on OLB larvae in learning condition C had significantly greater paralysis efficiency and higher OLB larvae parasitism rates than other parasitoids tested. Parasitoids fed on EAB larvae in learning condition A had the lowest paralysis efficiency and OLB larvae parasitism rates among the parasitoids tested. These findings suggested that adaptive learning significantly enhanced the ability of a generalist parasitoid to utilize a novel host. This may provide a new approach to controlling non‐natural hosts using generalist parasitoids.     

The effect of host size on the sex ratio of Syngaster lepidus, a parasitoid of Eucalyptus longhorned borers (Phoracantha spp.)

The solitary larval ectoparasitoid, Syngaster lepidus Brullé, parasitizes the cryptic larvae of two wood-boring beetles, Phoracantha recurva Newman and Phoracantha semipunctata F. The objective of this study was to determine how the female parasitoids allocated the sex of progeny when presented with larval hosts of uniform size classes. Host size was directly correlated with age of the Phoracantha larval hosts. Groups of Phoracantha larvae of a single age class (2-, 3-, 4-, or 5-week-old) were exposed to parasitoids, and sex ratios of the resulting parasitoid progeny from each host age class were determined. A significant relationship was observed among the sizes of P. recurva and P. semipunctata hosts and the sex ratio of emerging parasitoids. Parasitized 2-week-old beetle larvae of both Phoracantha spp. produced only male S. lepidus progeny, whereas older larval hosts produced increasing proportions of female parasitoids (up to 80% females from 5-week-old hosts). Two-week-old Phoracantha larvae of both species produced fewer parasitoids than host larvae 3–5-week-old. The size of parasitoid progeny consistently increased with host larval age (size), and female parasitoids were larger than males across all host size classes. Male S. lepidus developed in approximately 25 days from 2-week-old hosts, and 19–21 days in 3–5-week-old hosts. Female S. lepidus developed in 22–25 days, with developmental time increasing with host size.     

Plasticity in life features,parasitism and super-parasitism behavior of Bracon hebetor,an important natural enemy of Galleria mellonella and other lepidopteran host species

The wasp, Bracon hebetor Say, is an important potential biocontrol agent of a wide range of lepidopteran insect species. The current study was subjected to compare these ectoparasitoid fitness traits on different host species belonging to the order Lepidoptera. Moreover, we determine the population dynamic with different host densities, sex ratio patterns, super-parasitism, longevity, paralysis success, and reproductive potential under laboratory conditions. Our results revealed that oviposition increased with an increase in host density, while the adult emergence and egg hatching were decreased due to the super-parasitism on host larvae. A higher male and female-biased population were observed when virgin and mated females offered fresh hosts. Adults' longevity was recorded more in females than males when kept only with bee honey + royal jelly + host larvae. The mean duration of egg-adult development was recorded higher on Galleria mellonella and lowest on Busseola fusca. The parasitization rate, super-parasitism, and cumulative fecundity of mated and virgin female wasps with different host species were observed higher on specific host Galleria mellonella while it was lower on Phthorimaea operculella. Furthermore, the parasitoids having mating experience preferred fresh, while the parasitoids' lack of mating experiences preferred paralyzed host under olfactometer test. Besides, this research has produced novel facts on the biology of parasitic wasp, B. hebetor that may guide the advancement of sustainable biological control programs to control lepidopteran pests.     

Resistance of Drosophila suzukii to the larval parasitoids Leptopilina heterotoma and Asobara japonica is related to haemocyte load

Unlike other Drosophila species, the invasive Drosophila suzukii Matsumura (Diptera: Drosophilidae) shows a remarkable pest status. Among the physiological traits that may explain the high level of resistance to parasitoids of Drosophila larvae, the haemocyte load is shown repeatedly to play an important role. To determine whether haemocyte load can explain immunity resistance of D. suzukii to parasitoids, the haemocytes of parasitized and healthy larvae are quantified in two Japanese and three French populations of D. suzukii. Parasitization tests are conducted with two larval parasitoids: the paleartic Leptopilina heterotoma Thomson (Hymenoptera: Figitidae) and the Asian Asobara japonica Belokobylskij (Hymenoptera: Braconidae). Based on morphological and functional criteria, D. suzukii has classes of haemocytes similar to those described in Drosophila melanogaster. However, healthy larvae of the five populations tested possess particularly large numbers of haemocytes compared with D. melanogaster. Haemocyte load is also higher in larvae from the French populations than in the Japanese strains. The ability of D. suzukii larvae to encapsulate eggs of L. heterotoma is associated with a particularly high load of circulating haemocytes. However, it is notable that A. japonica induces a strong depression of the haemocyte population in this resistant host associated with an inability to encapsulate parasitoid eggs. The results show that the cellular immune system plays a major role in the failure of larval parasitoids to develop in most instances in larvae of D. suzukii, possibly contributing to the success of this species as an invader.     

Facultative gregarious development in a solitary koinobiont parasitoid,Ephedrus californicus: implications of larval ecology and host constraints

In solitary parasitoids, the mandibulate first instars behave aggressively towards potential competitors so that generally only one larva survives per host. A ‘failure of competition’ may result in facultative gregarious development, however. We used Ephedrus californicus Baker (Hymenoptera: Braconidae: Aphidiinae), a solitary koinobiont parasitoid of aphids, to test two hypotheses in the laboratory that could explain facultative gregarious development. Gregarious development increased with the intensity of parasitism, with two (rarely three) parasitoids successfully developing in a single aphid. In heavily superparasitized hosts, interference between surviving larvae often caused abnormal pupation behaviour and inability to emerge from the mummy. The hypothesis that the survival of more than one larva per host is dependent on differences in larval age was not supported. The total body size in terms of dry mass of two males or two females developing together in the same host was higher than that of same‐sex counterparts developing singly. Females were larger than males with which they shared a host. Hypotheses about the evolutionary transition from a solitary to a gregarious lifestyle in parasitoid Hymenoptera have focused on lethal fighting between first instars but have ignored other constraints including immature mortality during later development and limiting host resources. Especially in species that pupate inside the dead host, specific requirements for pupation and emergence may determine whether one or several offspring per host can develop to adult.     

The parasitoid guild of larvae of Chrysophtharta agricola Chapuis (Coleoptera: Chrysomelidae) in Tasmania, with notes on biology and a description of a new genus and species of tachinid fly

Abstract  The taxonomic status of the parasitoid guild associated with the larvae of Southern Eucalypt Beetle ( Chrysophtharta agricola Chapuis) in Tasmania is discussed. The primary larval parasitoid complex comprised the tachinid flies Balde striatum gen. n., sp. n. and Paropsivora australis (Macquart) (Diptera: Tachinidae: Goniinae: Blondeliini), and Eadya paropsidis Huddleston & Short (Hymenoptera: Braconidae), while the hymenopteran hyperparasitoids included Perilampus tasmanicus (Cameron) (Perilampidae), Mesochorus sp. (Ichneumonidae) and possibly Meteorus sp. (Braconidae). Keys are provided to the three adult primary parasitoids and two adult hyperparasitoids, and to the pupae of primary parasitoids. Balde striatum gen. n., sp. n. is described, and P. australis is redescribed. Brief notes on biology are included.     

Mortality factors affecting immature stages of codling moth,Cydia pomonella (Lepidoptera: Tortricidae), and the impact of parasitoid complex

Codling moth, Cydia pomonella Linnaeus (Lepidoptera: Tortricidae), is a serious pest of apples worldwide. This study aimed to evaluate the mortality rate of codling moth eggs, larvae and pupae in the field in commercial and neglected apple and walnut orchards over two years, and to investigate the biodiversity and intensity of parasitoids associated with codling moth in the orchards. Five patches of wax paper containing 1-day-old codling moth eggs were placed in a neglected orchard in order to evaluate parasitism rates. Corrugated cardboard bands were placed around the trunk of 15 trees during late spring and the beginning of summer through to fruiting season to capture and measure parasitism of codling moth larvae. 5285 larvae in total were collected during this study. Mortality rate (egg?+?larvae?+?pupae) varied between the commercial and neglected orchards, reaching a maximum of (42.89% and 66.67%) in neglected apple orchards and (61.03% and 74.76%) in the neglected walnut orchard in 2003 and 2004, respectively. Trichogramma cacoeciae (Hymenoptera: Tichogrammatidae) was the only egg parasitoid recorded. Eight hymenopteran larval and pupal parasitoids belonging to several subfamilies were recorded: Cheloninae, Agathidinae, Cremastinae, Haltichellinae, Chalcidinae, Anomalinae, and Pteromalinae and one dipteran belonging to Tachininae. In conclusion, mortality factors, mainly by parasitoids, are contributing to a general reduction in codling moth larvae populations particularly in neglected orchards. The hymenopteran Ascogaster quadridentata and the dipteran Neoplectops pomonellae can contribute to biological control programmes against codling moth in the coastal region and other regions.     

The life history and larval morphology of Aperilampus (Hymenoptera: Chalcidoidea: Philomidinae), with a discussion of the phylogenetic affinities of the Philomidinae

Abstract. The host association and larval morphology of Aperilampus (Hymenoptera: Chalcidoidea: Philomidinae) are documented for the first time based on specimens collected during the excavation of ground-nesting bee nests in South Africa. Aperilampus varians Strand is a primary parasite of the pupa of Halictus (Seladonia) africanus Friese (Hymenoptera: Halictidae). The first and final-instar larvae are described and illustrated, and notes are provided on the behaviour of the first-instar larva. The first-instar larva is a planidium and synapomorphies are documented between the first-instar larva of Aperilampus and the planidia of Chrysolampinae, Perilampidae and Eucharitidae.     

Food web associations and effect of trophic resources and environmental factors on parasitoids expanding their host range into non‐native hosts

Trophic interactions and environmental conditions determine the structure of food webs and the host expansion of parasitoids into novel insect hosts. In this study, we investigate plant–insect–parasitoid food web interactions, specifically the effect of trophic resources and environmental factors on the presence of the parasitoids expanding their host range after the invasion of Chrysodeixis chalcites (Esper) (Lepidoptera: Noctuidae). We also consider potential candidates for biological control of this non‐native pest. A survey of larval stages of Plusiinae (Lepidoptera: Noctuidae) and their larval parasitoids was conducted in field and vegetable greenhouse crops in 2009 and 2010 in various locations of Essex and Chatham‐Kent counties in Ontario, Canada. Twenty‐one plant–host insect–host parasitoid associations were observed among Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae), C. chalcites, and larval parasitoids in three trophic levels of interaction. Chrysodeixis chalcites, an old‐world species that had just arrived in the region, was the most common in our samples. The larval parasitoids Campoletis sonorensis (Cameron) (Hymenoptera: Ichneumonidae), Cotesia vanessae (Reinhard), Cotesia sp., Microplitis alaskensis (Ashmead), and Meteorus rubens (Nees) (all Hymenoptera: Braconidae) expanded their host range into C. chalcites changing the structure of the food web. Copidosoma floridanum (Ashmead) (Hymenoptera: Encyrtidae) was the most common parasitoid of T. ni that was not found in the invasive species. Plant species, host abundance, and agro‐ecosystem were the most common predictors for the presence of the parasitoids expanding their host range into C. chalcites. Our results indicate that C. sonorensis, C. vanessae, and C. floridanum should be evaluated for their potential use in biological control of C. chalcites and T. ni.     

Facultative gregarious development in a solitary parasitoid wasp,Dendrocerus carpenteri: larvae may share nutritional resources

Solitary parasitoids generally produce only one offspring per host. Dendrocerus carpenteri (Curtis) (Hymenoptera: Megaspilidae) develops as an idiobiont ectoparasitoid on prepupae and pupae of primary aphid parasitoids inside the mummified aphid host. Females normally deposit a single egg but superparasitize when suitable hosts are scarce. We show that facultative gregarious development may occur but is constrained by resource competition between larvae. The probability of more than one offspring surviving increased with the intensity of parasitism; an age difference of ≤9 h between older and younger first instars did not promote gregarious development. Two female parasitoids and, rarely, up to three male parasitoids could develop together. Average body size in terms of dry mass did not differ between singly developing females and the combined mass of two females sharing host resources, but the combined mass of gregarious males was greater than that of their singly developing counterparts. Females were 3× more likely to eclose from single than gregarious mummies. The amount of host resources available per larva declines with increasing clutch size, in turn causing a corresponding reduction of adult size and size‐dependent fitness attributes. We suggest that competition for limiting host supplies may influence the transition from solitary to gregarious development and should be considered in models of clutch size evolution in parasitoid wasps.     

Parasitoids of medfly, Ceratitis capitata, and related tephritids in Kenyan coffee: a predominantly koinobiont assemblage

Arabica coffee was sampled from two sites in the central highlands of Kenya (Rurima, Ruiru) and one site on the western side of the Rift Valley (Koru). Three species of ceratitidine Tephritidae, Ceratitis capitata (Wiedemann), C. rosa Karsch and Trirhithrum coffeae Bezzi, were reared from sites in the central highlands, and an additional species, C. anonae Graham, was recovered from the western-most site. Ten species of parasitic Hymenoptera were reared from these tephritids. The parasitoid assemblage was dominated by koinobionts. Eight of the species are koinobiont endoparasitoids, but only one idiobiont larval ectoparasitoid was reared, and only one idiobiont pupal endoparasitoid. The effects of sampling bias on determination of parasitoid assemblage size associated with concealed hosts are discussed. The potential for use of these parasitoids in biological control is also discussed. Most of the parasitoid species recovered during this study are capable of developing on C. capitata, while several also attack C. rosa. Both flies are notorious pests of tropical and subtropical fruits.