Peculiarities of muscles and skeleton structure in <Emphasis Type="Italic">Campiglossa plantaginis</Emphasis> (Haliday, 1833) ovipositor (Diptera,Terthritidae) in association with larval mode of life

Sclerites and muscles of the ovipositor in the tephritid fly Campiglossa plantaginis (Haliday, 1833), with phytophagous larvae developing in inflorescences of Aster tripolium L. and other Asteraceae, were examined. Structural adaptations of the ovipositor, providing oviposition into different substrates, are discussed in relation to different trophic specialization of larvae.     

Interspecific competition between the ichneumonid Campoletis chlorideae and the braconid Microplitis mediator in their host Helicoverpa armigera

We investigated interspecific competition between Campoletis chlorideae Uchida (Hymenoptera: Ichneumonidae) and Microplitis mediator (Haliday) (Hymenoptera: Braconidae) in their host, the cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) under laboratory conditions. Cotton bollworm larvae were allowed to be parasitized by both wasp species simultaneously or sequentially at different time intervals. When host larvae were parasitized simultaneously by both parasitoids, the majority of the cocoons produced were of M. mediator. When host larvae were parasitized initially by M. mediator followed by C. chlorideae at 12 or 24 h, parasitoids emerging from the multiparasitized hosts were mainly M. mediator. In contrast, when host larvae were parasitized initially by C. chlorideae, followed by M. mediator 12 or 24 h later, parasitoids emerging from the multiparasitized hosts were mainly C. chlorideae. Dissections of host larvae at various time intervals after parasitization by the two parasitoids showed that first instars of M. mediator could physically attack the larvae of C. chlorideae, but not the eggs of C. chlorideae. When a host was parasitized by both wasp species sequentially, more host larvae died and the number of wasp offspring was significantly reduced compared to a host parasitized by only one wasp. Conversely, in simultaneous multiparasitism, the host mortality and wasp offspring production were not significantly different from those parasitized by single wasp species.     

New data on the systematics of the palaearctic species of the <Emphasis Type="Italic">Dolichopus signifier</Emphasis> group (Diptera,Dolichopodidae)

Three new species of the genus Dolichopus Latr. (Diptera, Dolichopodidae) are described. All these species are closely related to Dolichopus signifer Haliday, 1832 and form a species-group including this species. Dolichopus taimyricus sp. n. is described from the southern tundra of the Taimyr Peninsula (northern Central Siberia); D. zlobini sp. n. was collected in the Pamirs (Tajikistan) and D. asymmetricus sp. n., in the mountains of Kazakhstan, Tajikistan, and Uzbekistan. A key to all these species of the group is given.     

Effects of the mixed biocide Bacillus thuringiensis–abamectin on the development of the parasitoid Microplitis mediator and its host Helicoverpa armigera

The effects of the mixed biocide Bacillus thuringiensis Berliner with abamectin (BtA) on the development of the parasitoid Microplitis mediator (Haliday) (Hymenoptera: Braconidae) and its cotton bollworm host, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), were evaluated in the laboratory. Weight gain in larvae of H. armigera was initially delayed, but larval developmental period increased and pupal weight increased when they were fed on a diet containing BtA. Due to increased longevity of the host larvae, the susceptible period to parasitization of H. armigera by M. mediator increased when the host larvae were reared on diets containing BtA at concentrations of 0.5, 1, 2, and 4 μg g^?1. The longevity of female and male parasitoids significantly decreased when newly emerged wasps were fed a honey solution containing 200 μg ml^?1 BtA in comparison with those fed only a honey solution. Mean longevity was significantly prolonged when parasitoids were fed a honey solution and BtA–honey solution in comparison with those fed BtA–distilled water, distilled water, or nothing. There were no significant differences compared with the control in any biological characteristics for the offspring of female parasitoids fed the honey solutions containing BtA at concentrations of 50, 100, and 200 μg ml^?1; characteristics measured include the egg‐larval period, pupal weight, male and female pupal periods, adult fresh weight, and adult longevity. When female parasitoids parasitized host larvae that had been fed the diet containing BtA, their male and female pupal periods were significantly prolonged compared with the control (without BtA).     

Movement of transgenic plant-expressed Bt Cry1Ac proteins through high trophic levels

The movement of Bacillus thuringiensis (Berliner) (Bt) Cry1Ac endotoxin through high trophic levels was assessed to help elucidate the effects of Bt toxin on non‐target insects. The diamondback moth (Plutella xylostella L., Lepidoptera: Plutellidae), the parasitic wasp (Cotesia vestalis Haliday, Hymenoptera: Braconidae) and the predatory green lacewing Chrysoperla carnea (Stephen) (Neuroptera: Chrysopidae) were used as a model system in this laboratory study. Bt‐resistant P. xylostella larvae fed Cry1Ac‐expressing transgenic oilseed rape (OSR, Brassica napus L., Cruciferae), before and after parasitization by C. vestalis, consumed Cry1Ac with the ingested plant material but only a proportion of Cry1Ac consumed was recovered from the bodies and faeces of P. xylostella larvae. Cry1Ac was not detected in newly emerged parasitoid larvae. In contrast, Cry1Ac was detected in C. carnea larvae fed on resistant P. xylostella larvae reared on Bt OSR. However, no Cry1Ac could be detected in C. carnea larvae when the lacewings were transferred to P. xylostella larvae reared on conventional OSR and tested 24–48 h. The metabolizing ability of Cry1Ac is discussed for the larvae of P. xylostella and C. carnea.     

Win,Lose, or Draw: Effects of Residency,Size, Sex,and Kinship on High‐Stakes Larval Contests in a Moth

Many factors can affect the outcome of a competitive interaction. One such factor is the relatedness between competitors as competitive intensity may decrease between kin. Because adult females lay eggs in clusters, larvae of the moth Utetheisa ornatrix are likely to be found in high densities of their siblings. Larval U. ornatrix actively compete for access into seedpods of their host plant (Crotalaria spp.), and successful competitors will reap numerous reproductive benefits during adulthood. The objective of this study was to determine whether residency, size, sex, and relatedness affect competition over seedpods in U. ornatrix larvae. In one‐on‐one trials for access into artificial seedpods, we monitored occupancy and weight change of larvae varying in residency, size, sex, and relatedness. We found that larger larvae have a competitive advantage over smaller larvae. This finding has consequences for the mating system of U. ornatrix in that females, by selecting males based on pheromone levels that are correlated with body size, can rear larger offspring that will have an advantage in competition over seedpods. These data did not support our hypothesis that males would outcompete females, perhaps because the rewards of acquiring a seedpod are substantial for both sexes. Finally, our data show that resident larvae are more likely to maintain control of seedpods over sibling than non‐siblings intruders, which suggests that relatedness affects competitive interactions.     

Seasonal phenology and stage-specific parasitism of the apple ermine moth, Yponomeuta malinellus Zeller, in Korea

The apple ermine moth, Yponomeuta malinellus Zeller (Lepidoptera: Yponomeutidae), is a tent caterpillar that feeds on Malus spp. in Korea. Populations of the moth in native areas appeared to be regulated by the assemblage of parasitoids. Phenological associations between host stages and parasitoids, susceptible stage(s) of the host for each parasitoid, and stage‐specific parasitism were studied. The egg larval parasitoid Ageniaspis fuscicollis (Dalman) had highest parasitism of first instar larvae (24%), with 14% parasitism of other larval stages. Dolichogenidea delecta (Haliday) was recovered from all larval instars with the highest parasitism rate of second instar larvae (20.1%), followed by 19.9% parasitism of mid‐larval hosts. Herpestomus brunicornis Gravenhorst was reared from second instar larvae through to pupal collection, and had the highest parasitism rate (29.9%) at the pupal stage. The larval pupal parasitoid Zenillia dolosa (Meigen) was recovered from mid‐larval to pupal stages with the highest parasitism rate (5.5%) occurring in third to fourth instar larvae. The host stages for developing A. fuscicollis completely overlap with those of D. delecta, and with those of H. brunicornis to some degree. A statistically significant negative correlation exists between A. fuscicollis and these dominant parasitoids, indicating competitive interaction within the host.     

Effects of the Cry1Ac toxin of Bacillus thuringiensis on Microplitis mediator, a parasitoid of the cotton bollworm, Helicoverpa armigera

Interactions between the cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), its larval parasitoid Microplitis mediator (Haliday) (Hymenoptera: Braconidae), and the Cry1Ac toxin of Bacillus thuringiensis Berliner were evaluated under laboratory conditions. The growth of H. armigera larvae was delayed and its pupal rate and pupal weight decreased when they were fed on a diet containing Cry1Ac toxin. Due to the lowered growth rate of the host larvae, the time available for parasitization of H. armigera by M. mediator increased when the host larvae were reared on a diet containing Cry1Ac toxin at concentrations of 0.5, 1, 2, and 4 µg g^?1. The longevity of female and male parasitoids was not significantly affected when newly emerging wasps fed on honey solutions containing three different concentrations of Cry1Ac toxin (125, 250, and 500 µg ml^?1). When female parasitoids were fed on honey solutions containing Cry1Ac, their offsprings’ egg and larval development period, pupal weight, length of pupation, adult weight, and adult longevity did not change significantly in most of the treatments compared with controls. When the female parasitoids parasitized host larvae that had been fed on a diet containing 0.5, 1, 2, 4, and 8 µg g^?1 Cry1Ac toxin, their offsprings’ eggs and larvae were significantly delayed. Their pupal weight, adult weight, and adult longevity were also significantly less than controls.     

Influence,or the lack thereof,of host phenology,architecture and climate on the occurrence of Udranomia spitzi (Hesperiidae: Lepidoptera)

The occurrence of herbivores in nature is limited by biotic and abiotic factors which affect their development and survival. Udranomia spitzi is an endemic butterfly in the Brazilian savanna (cerrado) that feeds on young leaves of two sympatric plants, Ouratea hexasperma and O. spectabilis. It is not known which factors affect the occurrence of larvae on their hosts. Therefore, in this study we: (i) evaluated the oviposition preference of U. spitzi; (ii) evaluated the larval performance in both Ouratea species; (iii) investigated plant phenology; (iv) investigated climate (temperature and rainfall); and (v) investigated plant architecture (measured as plant height) on the abundance of skippers. Results showed that U. spitzi immatures (eggs and larvae) were far more abundant (n = 41, 96.7%) on O. spectabilis, whereas on O. hexasperma, the number of larvae was negligible (n = 1). In the laboratory, U. spitzi performed better on O. spectabilis than on O. hexasperma. The occurrence of larvae was not related to host phenology or environmental variations, but rather to plant height, since 92.7% (n = 38) of larvae were found on small O. spectabilis trees. A previous study showed that U. spitzi was not influenced by biotic factors (aggressive ants) and this study showed that plant structure plays a major role in skipper choice. The preference of U. spitzi for O. spectabilis is discussed.     

Effects of quantitative and qualitative differences in volatiles from host‐ and non‐host‐infested maize on the attraction of the larval parasitoid Cotesia kariyai

Cotesia kariyai Watanabe (Hymenoptera: Braconidae) is a specialist larval parasitoid of Mythimna separata Walker (Lepidoptera: Noctuidae). Cotesia kariyai wasps use herbivore‐induced plant volatiles (HIPVs) to locate hosts. However, complex natural habitats are full of volatiles released by both herbivorous host‐ and non‐host‐infested plants at various levels of intensity. Therefore, the presence of non‐hosts may affect parasitoid decisions while foraging. Here, the host‐finding efficiency of naive C. kariyai from HIPVs influenced by host‐ and non‐host‐infested maize [Zea mays L. (Poaceae)] plants was investigated with a four‐arm olfactometer. Ostrinia furnacalis Guenée (Lepidoptera: Crambidae) was selected as a non‐host species. One unit (1 U) of host‐ or non‐host‐infested plant was prepared by infesting a potted plant with five host or seven non‐host larvae. In two‐choice bioassays, host‐infested plants fed upon by different numbers of larvae, and various units of host‐ and non‐host‐infested plants (infestation units; 1 U, 2 U, and 3 U) were arranged to examine the effects of differences in volatile quantity and quality on the olfactory responses of C. kariyai with the assumption that volatile quantity and quality changes with differences in numbers of insects and plants. Cotesia kariyai was found to perceive quantitative differences in volatiles from host‐infested plants, preferring larger quantities of volatiles from larger numbers of larvae or plants. Also, the parasitoids discriminated between healthy plants, host‐infested plants, and non‐host‐infested plants by recognising volatiles released from those plants. Cotesia kariyai showed a reduced preference for host‐induced volatiles, when larger numbers of non‐host‐infested plants were present. Therefore, quantitative and qualitative differences in volatiles from host‐ and non‐host‐infested plants appear to affect the decision of C. kariyai during host‐habitat searching in multiple tritrophic systems.     

Juvenile hormone regulates the titer of a hemolymph factor that enhances ecdysone synthesis by insect (Manduca sexta) prothoracic glands in vitro

The hemolymph of last instar Manduca sexta larvae contains a protein factor that enhances ecdysone synthesis by prothoracic glands in vitro. The titer of the factor fluctuates during development in a pattern that suggests that it is regulated by juvenile hormone (JH). In untreated control larvae, the titer drops from 2.17 U ml^?1 on day 1 to 0.27 U ml^?1 on day 3. When larvae were treated with (7S)-hydroprene (a JH analog), the titer remained elevated (2.09 U ml^?1 on day 3). JH I, however, was ineffective in preventing the precommitment drop in the titer of the factor. After pupal commitment, the titer of the factor increases in untreated larvae from 0.84 U ml^?1 on day 5 to 1.62 U ml^?1 on day 7. This increase was blocked when the sources of JH (the corpora allata) were removed on day 5 by head ligation. When head-ligated day 5 larvae were treated with either (7S)-hydroprene or JH I, the titer of the factor was driven to a level (1.88 U ml^?1 and 2.05 U ml^?1, respectively) that was not significantly different from that found in untreated day 7 larvae (1.62 U ml^?1). The combined results indicate the titer of the hemolymph factor is regulated by JH.     

A flagellate protozoan from Mythimna separata (Lepidoptera: Noctuidae)

Abstract

A trypanosomatid flagellate, Herpetomonas sp., is recorded from an adult Mythimna separata (Walker) (Lepidoptera: Noctuidae). Promastigote, paramastigote, and opisthomastigote stages measured 3.4–12 × 1.3–4.3 μm, Giemsastained, with flagella measuring 13.8–18.7 μm. A few amastigotes (3.9–8.3 × 3.7–6.7 μm) were also observed. Fourteen larvae fed with a suspension of flagellates were found later to be infected with the protozoan. No flagellate infections were found in the hymenopteran parasitoid, Apanteles ruficus (Haliday), or the hyperparasitoid, Trichomalopsis sp.     

Inter‐specific competition and competition‐free space in the tephritid parasitoids Utetes anastrephae and Doryctobracon areolatus (Hymenoptera: Braconidae: Opiinae)

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Intrinsic competition among solitary and gregarious endoparasitoid wasps and the phenomenon of ‘resource sharing’

1. Intrinsic competition was compared in three species of braconid wasps, the solitary Meteorus pulchricornis Wesmael, and the gregarious Cotesia kariyai (Watanabe) and Cotesia ruficrus Haliday in caterpillars of their common host, the armyworm Mythimna separata Walker. Competition was determined in pair‐wise contests consisting of simultaneous and subsequent parasitisms at various time intervals between the first and second attacks (<1, 24, 48, 72, and 96 h). 2. The experiment revealed that the solitary M. pulchricornis parasitoid was generally superior over the other two gregarious Cotesia species, although, in some cases C. kariyai out‐competed M. pulchricornis when ovipositing first. In contrast, irrespective of the time interval between parasitism and multiparasitism, C. ruficrus always lost in competition with M. pulchricornis. 3. Remarkably, both C. kariyai and C. ruficrus occasionally emerged from the same multiparasitised caterpillar when the time interval between the first and second attacks was small. However, cumulative brood sizes of both species were generally less than when C. kariyai and C. ruficrus developed alone, suggesting that some competition did occur between these two species. 4. Inter‐specific ‘resource sharing’ amongst parasitoid larvae has rarely been described in the literature. In the present study, the conditions in which ‘resource sharing’ in parasitoids can evolve are discussed. Further, we describe differing host usage strategies in parasitoids and how these can affect the outcome of aggressive larval competition.     

Encounters with aphid predators or their residues impede searching and oviposition by the aphid parasitoid Aphidius ervi （Hymenoptera： Aphidiinae）

Intraguild predation （IGP） can be an important factor influencing the effective- ness of aphid natural enemies in biological control. In particular, aphid parasitoid foraging could be influenced by the presence of predators. This study investigated the effect of larvae of the predatory hoverfly Episyrphus balteatus DeGeer （Diptera： Syrphidae） and the multicolored Asian ladybird Harmonia axyridis Pallas （Coleoptera： Coccinellidae） on the foraging behavior of the aphid parasitoid, Aphidius ervi Haliday （Hymenoptera： Aphidiidae） in choice experiments using a leaf disc bioassay. Wasp response to chemical tracks left by those predator larvae was also tested. Parasitoid behavior was recorded using the Observer （Noldus Information Technology, version 5.0, Wageningen, the Netherlands）. The experiments were conducted under controlled environmental conditions using leaves of the broad bean plant, Viciafaba L. （Fabaceae） with Myzus persicae Sulzer （Homoptera： Aphididae） as the host complex. A. ervi females avoided aphid patches when larvae of either predator were present. A similar avoidance response was shown by A. ervi to aphid patches with E. balteatus larval tracks, whereas no significant response was observed to tracks left by H. axyridis larvae. It was concluded that IG predator avoidance shown by the aphid parasitoid A. ervi may be a factor affecting their distribution among host patches.     

The life parameters of a parasitoid Microplitis mediator (Hymenoptera: Braconidae), reared on cotton bollworm Helicoverpa armigera (Hübner) with Cry1Ac diet

Microplitis mediator (Haliday) is an important endoparasitoid of the cotton bollworm, Helicoverpa armigera (Hübner) in northern China. Interactions among H. armigera, its larval parasitoid M. mediator, and Cry1Ac over two generations were evaluated under laboratory conditions. The results indicated that the developmental period of M. mediator offspring's eggs and larvae were significantly delayed and pupal and adult weight were significantly less compared to the control when the female parasitoids parasitized H. armigera larvae that fed on diet containing 1, 2, 4 and 8 µg/g Cry1Ac. The female parasitoids emerged from the host fed diet containing 8 µg/g Cry1Ac could oviposit in healthy hosts, and their offspring's biological parameters (egg–larval period, pupal weight and adult weight), parasitism rate, abnormal cocoon rate and adult emergence were not significantly affected. Cry1Ac was detected in larvae and hemolymph of H. armigera, but not in the larvae of M. mediator. The results suggest that the observed significant effects on several fitness parameters of the F₁ M. mediator developed from H. armigera fed Cry1Ac diet most likely were host-quality mediated rather than direct effects of Cry1Ac.     

DOLICHOPODIDAE FROM SOUTHWESTERN CHINA— III: FOUR NEW SPECIES OF THE GENUS TACHYTRECHUS (DIPTERA)*

Abstract This paper describes four new species of the genus Tachytrechus Haliday 1851, from Guizhou in southwestern China, namely, T. absarista Wei, sp. nov., T. crysus Wei, sp. nov, T. crypsusoideus Wei, sp. nov. and T. modestus Wei, sp. nov. A key to all 9 named species is given. The type specimens are deposited in the author's collection.     

Helminth parasites of the Eurasian badger (<Emphasis Type="Italic">Meles meles</Emphasis> L.) in the Basque Country (Spain)

The helminthological study of 26 Eurasian badgers (Meles meles L.) in the Basque Country (northern Spain) revealed the presence of two trematode (Euryhelmis squamula and Brachylaima sp.), three cestode (Atriotaenia incisa, Mesocestoides sp. and Taenia sp.) and five nematode (Aonchotheca putorii, Physaloptera sp., Molineus patens, Uncinaria criniformis and Strongyloides sp.) species. All 15 individuals analysed for Trichinella sp. were negative. The coprological analysis (flotation and migration) revealed the excretion of strongylid, capillariid and trematode eggs, and Crenosoma sp. and Angiostrongylus sp. larvae. No sex- or age-related differences were found in the parasite burden or egg and larvae excretion. A. incisa and M. patens abundances were positively correlated, both species being negatively correlated with badger weight. The presence of adults of U. criniformis and strongylid eggs in faeces was not independent. Badgers excreting Angiostrongylus larvae were in poorer condition than those not excreting.     

Why do larvae of Utetheisa ornatrix penetrate and feed in pods of Crotalaria species? Larval performance vs. chemical and physical constraints

Larvae of Utetheisa ornatrix (L.)(Lepidoptera: Arctiidae) are found mainly inside unripe pods of several alkaloid‐bearing Crotalaria (Fabaceae) species. Although eggs are laid on the leaves, the larvae are usually found feeding on unripe seeds in the pods. In this work, we investigated the selective pressures that could explain why U. ornatrix larvae feed primarily on unripe pods with seeds and not on leaves. Our results showed that larval survivorship in the laboratory was unaffected by feeding on leaves or unripe seeds, and that larval development up to the pupal stage was better in larvae that fed on unripe seeds, although perforating unripe pods to reach seeds was costly in terms of survivorship. Females were also heavier when fed on unripe seeds, but there was no significant difference in the fecundity of females fed either of the two diets. Feeding on unripe seeds in pods had other benefits for U. ornatrix, including a lower predation rate for larvae that fed inside compared to larvae that fed outside the pods. Similarly, adults derived from larvae that fed on unripe seeds were preyed upon less frequently by the orb‐weaving spider Nephila clavipes than were adults that fed on leaves. The latter benefit may be closely related to the high concentration of pyrrolizidine alkaloids in unripe seeds, which is about five times more than in leaves. These alkaloids are sequestered by the larvae and transferred to adults, which then become chemically protected. However, this chemical defence does not protect the larvae against ants such as Ectatomma quadridens and Camponotus crassus. Pods with unripe seeds that confer physical protection to larvae and pyrrolizidine alkaloids that confer chemical protection to adults limit the use of leaves by U. ornatrix larvae.     

Plastic changes in head size during juvenile development of the butterfly <Emphasis Type="Italic">Pieris napi</Emphasis>

Among herbivorous insects, the ability to change adaptive traits plastically in response to novel host plants is advantageous for coping with sudden environmental shifts. The host plants in our study were two closely related species, viz., Arabis flagellosa (tougher leaves, i.e., they are physically defended) and A. gemmifera (softer leaves that are physiologically defended). We demonstrated that young larvae of the butterfly Pieris napi are able to plastically change head size during development in response to changes in food plant species. When larvae were fed the physically defended A. flagellosa, the head sizes of third instar larvae emerging from eggs originally collected from leaves of both A. flagellosa and A. gemmifera became identically larger. When larvae fed on the physiologically defended A. gemmifera, the head sizes of third instar larvae emerging from eggs originally collected from leaves of both A. flagellosa and A. gemmifera became identically smaller. When leaves of A. flagellosa were presented to fourth instars reared on A. flagellosa, larvae with larger heads consumed more food than those with smaller heads. In contrast, when leaves of the physiologically defended A. gemmifera were presented to fourth instar larvae reared on A. gemmifera, larvae with smaller heads processed more food than those with larger heads. Hence, larvae of P. napi retain the capacity for adaptive plastic responses to novel host plant species.