Solitary Parasitoid Research Articles

First record of family Xenasteiidae (Diptera: Brachycera: Cyclorrhapha) from India in association with Aleurodicus rugioperculatus Martin (Hemiptera: Aleyrodidae) with cautionary notes on associated parasitoids

First ever record of family Xenasteiidae (Diptera: Brachycera: Cyclorrhapha) from mainland India is provided. Most of the previous records of this family are from coastal sites, as they have usually been found on islands in the Indian and Pacific Oceans. For the first time biology and life stages of Xenasteia are illustrated. Xenasteia members were found associated with an exotic rugose spiraling whitefly (RSW) colony of Aleurodicus rugioperculatus Martin (Hemiptera: Aleyrodidae) in the coastal areas of Karnataka in southern India, however no direct obligate association could be diagnosed. Also for the first time Ooencyrtus sp. (Hymenoptera: Encyrtidae) was recorded from the genus Xenasteia as its solitary parasitoid. Worldwide, this is the first ever report of parasitism associated with any member of this little-known family Xenasteiidae.Erratum: The identity of the parasitoid reported as Anagyrus sp. in this article is now corrected as Ooencyrtus sp.

Some features of preimaginal development of aphidiines (Hymenoptera, Aphidiidae), their theoretical and applied significance

Aphidiine wasps (Aphidiidae) are known exclusively by a solitary endophagous parasitoids of aphids. They develop only on Aphidoidea representatives and are absent on Phylloxeroidea. The main difference between the Aphidoidea and Phylloxeroidea is that the first is characterized by both the oviparous and viviparous generations. High level of metabolism in the body of viviparous aphid provides the development of single aphidiine larva. An assumption is that the appearance of viviparous aphids in the superfamily Aphidoidea is the most important evolutionary factor determining the development of the family Aphidiidae (Hymenoptera). The aphidiine larva generally pupates and spins a cocoon inside the mummy (indurated skin of the dead parasitized aphid-host). The cases of external pupation of aphidiine wasps are described. These examples characterize the close relationship of the Aphidiidae with their ancestors from the Braconidae. The intrapopulation variability of localization of the cocoon relative to the mummies for Praon volucre (Haliday) are described. It is shown that some of features of the cocoon of aphidiine wasps and mummies of aphid-host are important for the taxonomic identification of the species.

Cotesia icipe sp. n., a new Microgastrinae wasp (Hymenoptera, Braconidae) of importance in the biological control of Lepidopteran pests in Africa

A new species of Microgastrinae, Cotesia icipe Fernández-Triana & Fiaboe, sp. n., is described from eastern Africa. It was reared in Kenya as a solitary parasitoid from two major amaranth pests, Spodoptera littoralis (Boisduval, 1833) and S. exigua (Hübner, 1808); study of specimens in collections also revealed its presence in four other countries in the Afrotropical region (Madagascar, Saudi Arabia, South Africa, and Yemen). Morphological, molecular and biological characters are used to describe the new species and to distinguish it from all 12 previously described species of Afrotropical Cotesia. Cotesia icipe shows potential in the biological control of key Lepidopteran pests in small scale farming conditions in Africa.

Interspecific competition between Peristenus spretus and Peristenus relictus (Hymenoptera: Braconidae), larval parasitoids of Apolygus lucorum (Hemiptera: Miridae)

Interspecific competition among different species of insect parasitoids may affect the establishment or efficacy of species used for biological control of a target pests. Peristenus spretus Chen & van Achterberg and Peristenus relictus Loan (syn. P. stygicus) (Hymenoptera: Braconidae) are two dominant solitary parasitoids of mirid bugs in China. In this study, interspecific competition between larvae of P. spretus and P. relictus for the nutrients inside their common host, the green plant bug (Apolygus lucorum Meyer-Dürin), as well as their extrinsic competition for host resources were investigated in the laboratory. We examined the effect of four different time intervals between oviposition by the two species (10 min, 24 h, 48 h, and 72 h) and two parasitoid sequences (i.e., P. spretus before P. relictus [Ps-Pr] and P. relictus before P. spretus (Pr-Ps)] in no-choice tests to measure nutrient competition between the two species. In choice tests, three densities of A. lucorum nymphs (40, 80, and 120) were presented to various combinations of P. spretus and P. relictus (1,1; 2,2; or 3,3 pairs). In addition, the developmental times of the immature stage (from egg to late instar larva) of P. spretus and P. relictus were determined. We found that neither the time interval between oviposition by the two competing species, nor the order the parasitoids attacked (Ps-Pr or Pr-Ps) had any influence on the percentage of parasitoid offspring that belonged a particular parasitoid species. Peristenus spretus dominated, accounting for 89.2–97.9% of parasitoid offspring in the no-choice nutrient competition experiment. Parasitoid sequence did, however, affect sex ratio in the dominant parasitoid’s offspring, with 48.2% of P. spretus offspring being female in the Pr-Ps sequence, while only 29.2% were female in the Ps-Pr sequence. Overall, in the host resource competition experiment, 64.7–82.2% of all emerged adult parasitoids of the offspring generation, for all host density treatments, were P. spretus. The percentage of emerged parasitoids that were a given species was significantly affected by host density, but neither by the number of pairs of P. spretus or P. relictus nor by the parasitoid density × host density interaction. The developmental time of the immature stage of P. spretus was 2.2 days shorter than that of P. relictus, an important factor in making P. spretus a superior competitor over P. relictus in all the competition trials. Based on these results, we conclude P. spretus will have an important advantage when competing with P. relictus, a factor that should be considered in any biological control program using these two parasitoids in China.

Host discrimination modulates brood guarding behaviour and the adaptive superparasitism in the parasitoid wasp Trissolcus semistriatus (Hymenoptera: Scelionidae)

AbstractBecause hosts utilized by parasitoids are vulnerable to further oviposition by conspecifics, host guarding benefits female wasps. The present study aims to test whether female adults regulate brood guarding behaviour by host discrimination in a solitary parasitoid Trissolcus semistriatus by presenting an intact or parasitized host egg mass to a female adult. Virgin females without oviposition experience have host discrimination ability, which enables them to adjust the number of eggs laid in the hosts. Mating experience increases superparasitism by female adults, whereas mated females achieve a higher discrimination ability as a result of oviposition experience and show a lower superparasitism rate. As expected, females exhibit brood guard after parasitizing an intact host egg mass, whereas those females visiting a previously parasitized host egg mass, do not. Because the survival of eggs in superparasitized hosts is relatively low, regulating brood guarding behaviour by host discrimination is adaptive for female wasps.

A note on parasitisation of top borer by Isotima javensis Rohwer (Hymenoptera: Ichneumonidae)

Isotima javensis is a solitary ecto parasitoid of the sugarcane top borer, S. exceptalis. It attacks the prepupal stage and deposits an egg either on the prepupa or near its vicinity. The extent of parasitisation was observed 2.12%, 4.28%, 7.14%, 5.88% and 5.23 % in I, II, III, IV and V broods of top borer, respectively. The contribution of mortality of pupae of the top borer by parasitisation is high in III and IV broods (Aug-Oct), the time when the brood infestation remains generally very high. The maximum female ratio (59.72%) was observed in III brood of parasitisation followed by 55.20 % in IV brood. In I and II broods, however more or less equal number of males and females can be observed in the field. Equality in the sex ratio at this time ensures fertilisation of almost all the females for retaining the vigour and vitality of the species. The absence of unfertilized parasites naturally removes the chances of parthenogenetic reproduction and thus the number of females gradually rises in the succeeding season. It is concluded that there are several attributes of parasitoid i.e. specific parasite of top borer; its life cycle is much shorter than its host; active throughout the period of activity of the host and even it hibernates under north Indian conditions which make it a good biocontrol agent. It is suggested that parasitoid may be exploited in biological control programme, more detailed study is required for mass multiplication in the laboratory on an alternate host, release technique and survival in the sugarcane field.

Incidence of superparasitism in the egg parasitoid, Ooencyrtus kuvanae Howard (Hymenoptera: Encyrtidae)

ABSTRACTThe encyrtid Ooencyrtus kuvanae is a solitary parasitoid of the gypsy moth, Lymantria dispar L. (Lepidoptera-Lymantridae) that is used in biological control programmes and whose mass rearing is influenced by superparasitism. The purpose of this study was to investigate the effect of the self-superparasitism of O. kuvanae at different host densities (5, 10, 15 and 20), female ages (3 and 5 days) and durations of exposure (1 and 5 days) under various laboratory conditions (25°C ± 1°C, RH 60 ± 5% and a 16:8 h light:dark photoperiod) as well as in a new laboratory host, Philosamia ricini (Danovan) (Lepidoptera: Saturniidae) of O. kuvanae. In this study, we determined the rate of egg superparasitism and adult emergence and recorded development time, longevity and body weight. Superparasitism increased with female age and the duration of exposure to parasitoids when females had access to five host eggs. Superparasitism increased the number of parasitoid offspring, but it resulted in male-biased (56.90%) progeny. Furthermore, superparasitism caused deleterious effects to the fitness of the progeny by prolonging the developmental process, and decreasing longevity. For example, we found that when four adults can emerge from one superparasitised host egg, the body size of the parasitoid offspring decreases significantly. Hence, superparasitism should be avoided when mass rearing O. kuvanae.

Conspecific and heterospecific host discrimination in two parasitoid species of the mealybug Pseudococcus viburni, the solitary Leptomastix epona and the gregarious Pseudaphycus flavidulus

Leptomastix epona (Walker) and Pseudaphycus flavidulus (Brèthes) (Hymenoptera: Encyrtidae) are endoparasitoids of the mealybug Pseudococus viburni (Signoret) (Hemiptera: Pseudococcidae). Leptomastix epona is a solitary parasitoid originating from Europe and P. flavidulus is a gregarious parasitoid from South America. Conspecific and heterospecific host discrimination was examined between unparasitised female adult mealybugs and others already parasitized, at different time intervals between the primary and the following oviposition. Female wasps of L. epona discriminate between unparasitized hosts and hosts parasitized 0-96 hours previously by a conspecific selecting more often the first over the latter for oviposition. Females of P. flavidulus discriminate between unparasitized hosts and hosts parasitized prior to 0-72 hours by a conspecific. Conspecific superparasitism also occurs in both parasitoid species. The secondary sex ratio of L. epona and the clutch size of P. flavidulus are not affected by superparasitism whereas the secondary sex ratio of P. flavidulus in superparasitized hosts is more male biased than in single parasitized hosts. The solitary parasitoid L. epona does not discriminate between unparasitized hosts and hosts parasitized by P. flavidulus 0-3 or 24 hours previously. Nevertheless the gregarious parasitoid P. flavidulus discriminates between unparasitized hosts and hosts parasitized by L. epona 0-3 hours earlier, but it oviposits without discrimination in hosts heterospecifically parasitized 24 hours beforehand. When multiparasitism occurs at 0-3 hours after the first oviposition, L. epona is a superior competitor regardless of which species oviposits first. However, when the time interval between the two ovipositions is 24 hours, the probability of the offspring of P. flavidulus winning the competition with L. epona increases when either species oviposits first. The potential effect of multiparasitism on parasitoid coexistence is discussed in relation to prospects for multiplespecies introductions or augmentative releases for the biological control of the mealybug.

Intra- and interspecific competition in two congeneric parasitoids of the diamondback moth

In solitary parasitoids, a host can only support the complete development of a single parasitoid. For this reason, intraspecific or interspecific competition takes place whenever two or more individuals of the same or different species parasitize the same host. The exotic Diadegma semiclausum (Hellen) (Hymenoptera: Ichneumonidae) was introduced into Kenya in 2002 for the control of the diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae), and led to the competitive displacement of its indigenous congeneric species Diadegma mollipla (Holmgren) in some areas but not in others. In an attempt to understand this process, superparasitism in D. mollipla and multiparasitism involving both species were investigated in the laboratory through exposure of non-parasitized and parasitized host larvae to D. mollipla. Hosts were exposed to the two congeners both simultaneously and sequentially. The study revealed that D. mollipla minimizes parasitism and superparasitism in the presence of hosts containing a larva of a conspecific female. When the two parasitoid species competed for non-parasitized hosts simultaneously, there were no significant differences in the total progeny produced under intraspecific vs. interspecific competition. Under simultaneous interspecific competition, D. semiclausum produced 74% of total progeny. Under sequential exposure, the species that attacked first always dominated with 85–96% of the resultant progeny, irrespective of the exposure interval. Offspring sex ratio was significantly more female-biased when the larvae were exposed to D. mollipla first. Overall, our results indicate that D. semiclausum dominates under simultaneous competition and D. mollipla dominates in terms of female progeny, but under delayed exposure to the other species, the first attacker is always the winner. On the basis of our results, D. semiclausum may not completely displace D. mollipla from diamondback moth in the field.

Biology and Thermal Requirements of Fopius arisanus (Sonan, 1932) (Hymenoptera: Braconidae) Reared on Ceratitis capitata Eggs (Wiedemann) (Diptera: Tephritidae).

Fopius arisanus (Sonan) is a solitary parasitoid of eggs and the first instar larvae of Tephritidae. Due to the occurrence of Ceratitis capitata (Wiedemann) in various regions and under several climatic conditions, this study aimed to evaluate the effect of different temperatures on the embryonic development (egg-adult) and determine thermal requirements and the number of annual generations F. arisanus on eggs of C. capitata. In the laboratory, eggs of C. capitata (24h) were submitted to parasitism of F. arisanus during 6h. Later, the eggs were placed in plastic containers (50mL) (50 eggs/container) on a layer of artificial diet and packed in chambers at temperatures 15, 18, 20, 22, 25, 28, 30, and 32±1°C, RH 70±10%, and a photophase of 12h. The largest number of offspring, emergence rate, and weight of adults of F. arisanus were observed at 25°C. The highest sex ratios (sr>0.75) were recorded at 15 and 18°C, being statistically higher than the temperatures 20°C (0.65), 22°C (0.64), 25°C (0.65), 28°C (0.49), and 30°C (0.47). At 32°C, there was no embryonic development of F. arisanus. The egg-adult period was inversely proportional to temperature. Based on the development of the biological cycle (egg-adult), the temperature threshold (T t) was 10.3°C and thermal constant (K) of 488.34 degree-days, being the number of generations/year directly proportional to the temperature increase. The data show the ability of F. arisanus to adapt to different thermal conditions, which is important for biological control programs of C. capitata.

Effects of superparasitism on immature and adult stages of Diachasmimorpha longicaudata Ashmead (Hymenoptera: Braconidae) reared on Ceratitis capitata Wiedemann (Diptera: Tephritidae).

The optimal use of available host by parasitoid insects should be favoured by natural selection. For solitary parasitoids, superparasitism (i.e. the egg-laying of several eggs/host) may represent a detrimental phenomenon both in a biological and an applied sense, but under certain circumstances it may be adaptive. Here, we studied the effects of increasing levels of superparasitism (LSPs, number of parasitoid larvae/host) on fitness-related parameters of the immature and adult stages of Diachasmimorpha longicaudata, a solitary endoparasitoid parasitizing Ceratitis capitata. We investigated the moment when supernumerary parasitoid larvae are eliminated and the effects produced by this process, together with its repercussion on female fecundity, parasitism rate, sex ratio, adult survival, flight ability and body size. Complete elimination of competitors occurred soon after larval hatching, before reaching the second larval stage. Elimination process took longer at higher LSPs, although a normal developmental (egg-adult) time was achieved. For LSPs 1, 2, 3 and 5 the effects on parasitoid emergence were mild, but LSP 10 led to the death of all developing parasitoids. Aside from this, to develop in superparasitized hosts did not significantly affect any of the evaluated parameters, and only a female-biased sex ratio was observed at higher LSPs. However, the effects of superparasitism on the adults may have a different outcome under more variable conditions in the field, once they are released for biological control purposes.

A new substitute host and its effects on some biological properties of Ooencyrtus kuvanae.

Lymantia dispar (L.) (Lepidoptera: Lymantriidae), commonly known as the gypsy moth, is a serious forest pest, and beneficial insects are particularly important for reducing its population numbers. Ooencyrtus kuvanae (Howard) (Hymenoptera: Encyrtidae) is an arrhenotokous, solitary egg parasitoid of L. dispar. In this study, we evaluated a new substitute host, Philosamia ricini (Danovan) (Lepidoptera: Saturniidae) for O. kuvanae. We investigated some of the biological effects of O. kuvanae on P. ricini eggs. In this context, the importance of the age of the female parasitoid (1, 3 or 5 days old), host age (1-2 and 3-4 days old) and host number (40, 60 and 80 host eggs) were examined under laboratory conditions (25 ± 1 °C, 65 ± 5% relative humidity and a 16 : 8 h photoperiod [light : dark]). The highest rate of offspring production (89.90%) occurred with 40 (1-2-day-old) host eggs and 5-day-old females. The mean developmental period ranged from 16.5 ± 0.08 days to 18.7 ± 0.08 days. The mean lifespan of the parasitoid was 51.10 ± 1.1 (n = 60) days with bio-honey and 3.92 ± 0.14 (n = 60) days without food. The mean fecundity was 68.88 ± 3.22 offspring/female. Peak adult emergence occurred between 2 and 9 days. The mean oviposition and mean post-oviposition periods of the female parasitoid were 22.76 ± 1.37 days and 13.64 ± 1.40 days, respectively. O. kuvanae was reared for more than ten generations on the eggs of P. ricini. Based on our findings, P. ricini can be used to rear O. kuvanae for the biological control of L. dispar.

Host-substrate preference of Theocolax elegans (Westwood) (Hymenoptera: Pteromalidae), a larval parasitoid of the maize weevil, Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae)

The solitary parasitoid Theocolax elegans (Westwood) (Hymenoptera: Pteromalidae) was investigated attacking larvae of the maize weevil, Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae) under laboratory conditions. T. elegans parasitoids were mass reared on 21-day-old S. zeamais fed with different host substrates consisting of brown rice, maize, sorghum and wheat. The developmental time of S. zeamais was observed. The widest head capsule was recorded from S. zeamais developing in brown rice grain kernels. The head capsule width was used to determine the age of the larval instars. The sex ratio of T. elegans progeny emerging from brown rice was the same in the choice and no-choice tests (1.8:1.0 and 1.8:1.0, respectively). Female parasitoids preferred to oviposit on S. zeamais developed in brown rice grain kernels in both tests. The number of parasitoid progeny emerging from different host substrates was different in the choice and no-choice tests. The progeny of T. elegans females and males were fully winged, short winged and wingless.

First report of the parasitoid Pachycrepoideus vindemmiae (Rondani, 1875) (Hymenoptera: Pteromalidae) parasitizing Synthesiomyia nudiseta (Van der Wulp, 1883) (Diptera: Muscidae).

The hosts of Pteromalidae include Hemiptera, Neuroptera, Coleoptera, Lepidoptera, Diptera, Siphonaptera, Hymenoptera, Dermaptera and Homoptera. Pteromalidae attack eggs, larvae, pupae or, rarely, adults. The main contribution of pteromalids towards insect control is in relation to muscoid flies, especially house flies and stable flies (Gauld and Bolton, 1988 ; Hanson and Gauld, 1995 ).The adults of some species of the family Muscidae are vectors, through their bite or in a passive manner, for the pathogens of diseases such as typhoid fever, dysentery, anthrax and African sleeping sickness. House flies overwinter in either the larval or pupal stage under manure piles or in other protected locations. This is the most common insect family found on pig and poultry farms, in horse stables and on ranches (Renaud et al., 2012).Synthesiomyia nudiseta (Van der Wulp, 1883) (Diptera: Muscidae) is a fly with Neotropical geographical distribution. In Brazil, it shows preference for inhabited areas, which makes this fly a potential vector for pathogens (Greenberg, 1971; Aruna et al., 2011; Velasquez et al., 2013).Pachycrepoideus vindemmiae (Rondani, 1875) (Hymenoptera: Pteromalidae) is to be a solitary parasitoid that controls a great number of Diptera in the families Anthomyiidae, Calliphoridae, Muscidae, Sarcophagidae, Tachinidae and Tephritidae. This species presents diversified (cosmopolitan) distribution and it has been found in North America and Africa (Hanson and Gauld, 1995).The objective of this paper was to report a new host for the parasitoid P. vindemmiae, which was collected in the urban region of Goiânia, in the central part of the state of Goias, Brazil.The experiment was conducted in the urban area of Goiânia, in the central part of the state of Goias, Brazil. The flies were collected by using traps, made of dark cans measuring 19 cm in height and 9 cm in diameter, with two openings resembling blinders, located in the lowest third of the can, to allow flies to enter. The top of the can was connected to a nylon funnel that was open at both ends, with the base pointing down. This was wrapped in plastic bags, so that when they were removed, the flies and parasitoids could be collected. The following items were used as baits: human feces, cattle kidneys, cattle liver, chicken and fish which were placed inside the cans, over a layer of earth. Five traps were used and they were hung on trees at a height of one meter above the ground, two meters apart from each other.The insects collected were taken to the laboratory, sacrificed with ethyl ether and kept in 70% alcohol for further identification. To obtain the parasitoids, the contents of the traps were placed in plastic containers with a layer of sand for use as a substrate for transformation of the larvae into pupae. This sand was sifted after being in the fields for 15 days and the pupae were extracted from it and were individually placed in gelatin capsules (number 00) in order to obtain the flies and/or parasitoids.The species were stored in the Biology Laboratory of Institute of Tropical Pathology and Public Health. The species identification was performed by one of the authors.The total percentage parasitism was calculated by means of the number of pupae parasitized, divided by the total number of pupae collected, and multiplied by 100.Between January and May 2014, two specimens of P. vindemmiae were collected from 26 pupae of S. nudiseta. The percentage parasitism observed was 7.7%. The percentage parasitism can also be correlated with the parasitoid’s search capacity and with the availability of resources.These dipterous insects are potential mechanical vectors for etiological agents such as viruses, bacteria, protozoan cysts and helminth eggs (Greenberg, 1971; Marchiori, 2006). The occurrence, distribution and prevalence of these dipterous insects in metropolitan areas are factors of great public health importance. In rural areas, these insects can cause decreased egg production and animal diseases, and they constitute a nuisance for human populations close to the breeding sites (Couri and Barros, 2010 ; Ekanem et al., 2013; Marchiori, 2007; Marchiori et al., 2014).Pachycrepoideus vindemmiae is considered a parasitoid of pupae of a great number of Diptera, including species of the genera Anastrepha, Calliphora, Ceratitis, Chrysomya, Drosophila, Fannia, Haematobia, Hylemya, Lucilia, Megaselia, Musca, Ophyra, Ornidia, Oxysarcodexia, Palaeosepsis, Paratheresia, Phaenicia, Phormia, Poecilosomella, Peckia,

Elicitation of superparasitization behavior from the parasitoid wasp Leptopilina boulardi by the organophosphorus insecticide chlorpyrifos.

Chlorpyrifos is an organophosphorus insecticide that largely contributes to environmental pollution. Parasitoids, as any other non-target species, can be exposed to insecticides through environmental pollution. Parasitoids are key species because they regulate natural populations of other insects. The hymenopterous parasitoid Leptopilina boulardi, whose larvae develop inside Drosophila larvae, is a solitary parasitoid; thus, only one larva can successfully develop per host. Therefore, females generally lay only one egg per host because any increase in the number of eggs laid will decrease its fitness. The effects of an LC20 of chlorpyrifos on the parasitization behavior of two strains (NS and S) of L. boulardi were evaluated. The NS and S strains were genetically identical but differed in that the S strain was infected by a virus, LbFV, which modifies the parasitization behavior of the parasitoid. In control conditions, parasitoid females from the NS strain rarely superparasitized (laid more than one egg per host) their host whereas females from the S strain frequently superparasitized their host. When parasitoids were exposed to an LC20 of chlorpyrifos, the rates of host larvae superparasitized by females and the mean numbers of eggs laid per host larva increased for both NS and S strains. Therefore, both the insecticide and the virus induced an increase in the superparasitization of the host. The effect of the insecticide on the superparasitization behavior of the parasitoid is discussed according to its mode of action.

Transcriptome profiling of Diachasmimorpha longicaudata towards useful molecular tools for population management.

Background Diachasmimorpha longicaudata (Hymenoptera: Braconidae) is a solitary parasitoid of Tephritidae (Diptera) fruit flies of economic importance currently being mass-reared in bio-factories and successfully used worldwide. A peculiar biological aspect of Hymenoptera is its haplo-diploid life cycle, where females (diploid) develop from fertilized eggs and males (haploid) from unfertilized eggs. Diploid males were described in many species and recently evidenced in D. longicaudata by mean of inbreeding studies. Sex determination in this parasitoid is based on the Complementary Sex Determination (CSD) system, with alleles from at least one locus involved in early steps of this pathway. Since limited information is available about genetics of this parasitoid species, a deeper analysis on D. longicaudata’s genomics is required to provide molecular tools for achieving a more cost effective production under artificial rearing conditions.ResultsWe report here the first transcriptome analysis of male-larvae, adult females and adult males of D. longicaudata using 454-pyrosequencing. A total of 469766 reads were analyzed and 8483 high-quality isotigs were assembled. After functional annotation, a total of 51686 unigenes were produced, from which, 7021 isotigs and 20227 singletons had at least one BLAST hit against the NCBI non-redundant protein database. A preliminary comparison of adult female and male evidenced that 98 transcripts showed differential expression profiles, with at least a 10-fold difference. Among the functionally annotated transcripts we detected four sequences potentially involved in sex determination and three homologues to two known genes involved in the sex determination cascade. Finally, a total of 4674SimpleSequence Repeats (SSRs) were in silico identified and characterized.ConclusionThe information obtained here will significantly contribute to the development of D. longicaudata functional genomics, genetics and population-based genome studies. Thousands of new microsatellite markers were identified as toolkits for population genetics analysis. The transcriptome characterized here is the starting point to elucidate the molecular bases of the sex determination mechanism in this species.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-2759-2) contains supplementary material, which is available to authorized users.

Combined use of herbivore‐induced plant volatiles and sex pheromones for mate location in braconid parasitoids

Herbivore-induced plant volatiles (HIPVs) are important cues for female parasitic wasps to find hosts. Here, we investigated the possibility that HIPVs may also serve parasitoids as cues to locate mates. To test this, the odour preferences of four braconid wasps - the gregarious parasitoid Cotesia glomerata (L.) and the solitary parasitoids Cotesia marginiventris (Cresson), Microplitis rufiventris Kokujev and Microplitis mediator (Haliday) - were studied in olfactometers. Each species showed attraction to pheromones but in somewhat different ways. Males of the two Cotesia species were attracted to virgin females, whereas females of M. rufiventris were attracted to virgin males. Male and female M. mediator exhibited attraction to both sexes. Importantly, female and male wasps of all four species were strongly attracted by HIPVs, independent of mating status. In most cases, male wasps were also attracted to intact plants. The wasps preferred the combination of HIPVs and pheromones over plant odours alone, except M. mediator, which appears to mainly use HIPVs for mate location. We discuss the ecological contexts in which the combined use of pheromones and HIPVs by parasitoids can be expected. To our knowledge, this is the first study to show that braconid parasitoids use HIPVs and pheromones in combination to locate mates.

Parasitoids of Gangara thyrsis (Fabricius) (Lepidoptera: Hesperiidae) with description of a new species of Agiommatus Crawford, 1911 (Hymenoptera: Pteromalidae) from India with notes on biology.

In rearing of Gangara thyrsis (Fabricius) (Lepidoptera: Hesperiidae) from Karnataka and Goa, India, six species of parasitoids were observed. One new species of parasitic wasp is described and illustrated: Agiommatus thyrsisae n. sp. (Hymenoptera: Pteromalidae), a solitary parasitoid reared from the egg of G. thyrsis on the natural host plant Dypsis lutescens (H. Wendl.) Beentje & J. Dransf. Three additional species of parasitic wasps were also reared: Anastatus ramakrishnai (Mani, 1935) (Hymenoptera: Eupelmidae), a solitary hyperparasitoid of A. thyrsisae n. sp.; Sympiesis thyrsisae Gupta, Gawas & Bhambure (Hymenoptera: Eulophidae), a gregarious parasitoid reared from the caterpillar of G. thyrsis on the host plant Cocos nucifera L., and Brachymeria lasus (Walker) reared from pupa of G. thyrsis on the host plant D. lutescens. Additionally, two species of tachinid flies were also reared from the pupae of G. thyrsis: Exorista sorbillans (Wiedemann, 1830) and an innominate species close to Blepharella spp. Gangara thyrsis is a new host record for the genus Agiommatus and for A. ramakrishnai and B. lasus. The mean percent parasitism in G. thyrsis eggs was 26.58% with an incubation period of 6-7 days. Amongst the egg parasitoids, 57.14-73.08% were females and 23.08% were males. Hyperparasitism ranged from 3.85 to 42.86%. Dypsis lutescens, a member of Arecaceae, is a new host plant record for G. thyrsis.

Host specialisation and competition asymmetry in coleopteran parasitoids.

When specialists and generalists compete for a limited resource, specialists are more constrained because they are less likely to find an alternative resource. In parasitoids with overlapping host ranges, asymmetric competition should therefore exist where specialists are more likely to win the host in a contest. Competition between parasitoids has been studied mostly in hymenopterans. In hymenopteran parasitoid wasps, females must reach the host to lay their eggs and can thus strongly influence the outcome of competition between future offspring by killing eggs or larvae of competitors. We studied competition between the free-ranging larvae of two sympatric coleopteran parasitoid rove beetles (one specialist, Aleochara bilineata and a generalist, Aleochara bipustulata) with overlapping host ranges competing in agricultural fields for pupae of the cabbage root fly. In these species, females lay their eggs in the soil, then first instars find the host where they will develop as solitary parasitoids and deal with potential competitors. Because adult longevity and fecundity favour the generalist, we postulated that first instars of the specialist would be superior larval competitors. Accordingly, we studied the outcome of encounters between first instars of the two species provided with a single host. Irrespective of its release prior to or simultaneously with its generalist competitor, the larva of the specialist most often won. Moreover, specialist larvae still won half of the encounters when generalist larvae were given a 24-h advantage. This might explain the coexistence of the two species in the field.

Effects of Temperature and Photoperiod on the Reproductive Biology and Diapause of Oobius agrili (Hymenoptera: Encyrtidae), an Egg Parasitoid of Emerald Ash Borer (Coleoptera: Buprestidae).

Oobius agrili Zhang and Huang (Hymenoptera: Encyrtidae) is a solitary egg parasitoid of the invasive emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), and has been introduced to the United States for classical biological control. We characterized the weekly survivorship, fecundity, and diapause patterns of both diapaused and nondiapaused populations of O. agrili under four different temperature-photophase combinations: 30°C (warm) and 20°C (cold) temperatures with both long-day (16 h) and short-day (8 h) photophase. Results of this study showed that regardless of the length of photophase, parental parasitoids of both diapaused and nondiapaused O. agrili survived significantly longer at 20°C than at 30°C. Both populations also laid their eggs faster at 30°C compared with those at 20°C. Higher proportions of the progeny produced by both populations of O. agrili were induced into diapause by short-day (8 h) photophase, regardless of rearing temperature. In addition, the diapaused parasitoids in the short-day photophase treatment at both warm and cold temperatures produced increasing proportions of diapaused progeny over time, whereas no significant differences were observed in the proportions of diapaused progeny by the nondiapaused parasitoids over different sampling times. These findings suggest that O. agrili should be continuously reared under warm temperature and long-day photoperiod (to avoid diapause for increased reproduction). In addition, we recommend that diapaused adults be used for field releases in early summer when temperatures are still relatively low (∼20°C) and host eggs are available so that they can produce multiple generations prior to overwintering.