松墨天牛成虫雌雄体型差异及蛹和成虫大小与越冬幼虫体重的关系

【目的】本研究旨在明确松墨天牛 Monochamus alteratus 成虫及越冬幼虫体型大小的差异,探讨该虫越冬后成虫体型大小和越冬幼虫体重大小关系及原因。【方法】于2014年5月1日至10月31日在浙江富阳野外诱捕松墨天牛,通过测量野外诱捕到的松墨天牛成虫体长、体宽,确定林间松墨天牛成虫体型的差异;松墨天牛越冬幼虫的采集和称重测量明确越冬幼虫的组成和体重大小差异;进而通过对越冬幼虫单头跟踪饲养至化蛹、羽化,确定越冬幼虫体重大小与发育所得蛹和成虫大小的关系,阐明林间松墨天牛成虫体型差异的原因。【结果】浙江富阳野外诱捕发现,松墨天牛的活动期间很长,从5月中旬到10月初一直能诱捕到松墨天牛成虫,高峰期在6和7月份。松墨天牛雌雄成虫体型差异很大,雌虫平均体长和体宽分别为20.59±0.19和6.59±0.06 mm;雄虫平均体长和体宽分别为19.90±0.26 和6.44±0.08 mm; 雌虫的平均体长明显高于雄虫,但二者体宽没有显著差异;并且雌雄成虫体长和体宽呈显著正相关。越冬幼虫的头宽测定表明头宽的变化很大,最小为2.20 mm,最大为4.24 mm,经比对越冬幼虫由4龄和5龄幼虫组成;幼虫体重差异大,平均体重为304.2 mg, 介于71.6~858.0 mg之间,其中5龄越冬幼虫显著重于4龄越冬幼虫。进一步将越冬幼虫单管饲养跟踪研究发现,越冬幼虫体重大小决定蛹和羽化后的成虫的大小,二者存在显著的正相关,并且由4龄越冬幼虫发育所得的蛹和成虫显著轻于由5龄幼虫发育所得的蛹和成虫。【结论】松墨天牛成虫体型差异很大,这与越冬幼虫体重差异相关;越冬幼虫的体重大小决定了其化蛹后的蛹重和羽化后成虫的体型和体重的大小;造成越冬幼虫体重差异的可能原因包括松墨天牛成虫扬飞周期长导致的产卵期长而使得天牛发育进度不一致以及寄主不同部位营养的差异。     

Phorid fly parasitism rates vary between individual colonies of the leaf-cutting ant Atta laevigata

1. Phorid flies are important natural enemies of leaf-cutting ants. Female phorids lay eggs in the worker ants' bodies and the parasitoid larvae feed on the host's internal tissues.
2. Here we investigated the parasitism rates by four species of phorids when attacking individual Atta laevigata colonies at three different field sites in order to further understand the host-parasitoid relationship.
3. There were distinct variations in parasitism rates when comparing phorid species attacking individual colonies. In 13 of the colonies sampled, parasitism by Apocephalus attophilus or Eibesfeldtphora erthali was predominant. However, in four of the colonies, Myrmosicarius grandicornis and Apocephalus vicosae were the predominant species.
4. Variations in parasitism rates by the four phorid species were investigated in relation to the size of the potential hosts that had been collected from the foraging trails of each colony.
5. When correlating the size of potential hosts to phorid species, ants with head capsule widths of >2 mm were predominantly parasitized by A. vicosae and E. erthali. Smaller ants, with head capsule widths of 2 mm or less, were predominantly parasitized by A. attophilus and M. grandicornis.
6. The highest parasitism rates by E. erthali were observed in individual colonies that had the highest proportions of large workers on the trails.
7. Although almost half the size of E. erthali, A. attophilus parasitized both large (head capsule width > 2 mm) and small workers (<2 mm). This was related to the fact that between 1 and 16 larvae can develop within an individual host, depending on host size.
8. M. grandicornis parasitized smaller workers (mean head capsule width = 2 mm) as these phorids are themselves small and only one larva develops within each host.
9. This study demonstrated that the parasitism profiles of individual A. laevigata colonies were related to the size of foragers on the trails.

     

Pelagic eggs and larvae of Coelorinchus kishinouyei (Gadiformes: Macrouridae) collected from Suruga Bay, Japan

Pelagic eggs and larvae of the macrourid fish Coelorinchus kishinouyei, collected from Suruga Bay, southern Japan and subsequently identified by 16S rRNA gene nucleotide sequences, are described. The spherical eggs, 1.18–1.31 mm in diameter, contained a single oil globule, 0.28–0.33 mm in diameter, and had hexagonally patterned ornamentation on the chorion, 0.017–0.022 mm in width. Melanophores were present on the embryo, yolk and oil globule after the blastopore had closed. Within 1 day after hatching, the body axis of the yolk-sac larvae was bent slightly at the anterior trunk region. During this stage many melanophores formed on the head, trunk, tail, yolk and oil globule, along with small irregular wrinkles on the dorsal and ventral finfolds. Pelagic eggs (after the caudal end of the embryo had detached from the yolk) and yolk-sac larvae also developed xanthophores on the embryo and yolk, and head, trunk, dorsal and ventral finfolds just before tail tip, and yolk, respectively. The pelagic larvae had a short tail, stalked pectoral-fin base and no elongate first dorsal and pelvic-fin rays. Three clusters of melanophores were present on the tail (anterior two embedded to muscle and one just before tail tip subsequently lost with development) and a cluster around the anus (beyond 3.9 mm head length). Nucleotide sequence analyses of comparative adult specimens appeared to confirm a previous proposal that C. productus is a junior synonym of C. anatirostris.     

Host range testing and life history of the defoliator Hymenomima nr. memor: an unsuitable biological control agent for Schinus terebinthifolia in the U.S.A.

Host range of larvae of Hymenomima nr. memor (Lepidoptera: Geometridae) was examined in quarantine to evaluate its suitability as a biological control of Brazilian peppertree, Schinus terebinthifolia. Brazilian peppertree, S. terebinthifolia is an environmental and agricultural weed from South America that had invaded many subtropical and tropical areas of the world including Florida and Hawaii, USA. Laboratory life history and quarantine host range studies of H. memor were conducted with no-choice feeding tests. These tests included eight species of the Anacardiaceae and one species of Sapindaceae. Larvae of H. memor had five to six instars with each head capsule width increasing by 1.68-X. Development time from neonate to adult was 46.7?±?2.2 days. In host range tests, neonates completed development to the adult stage on all non-target species, except Toxicodendron radicans. Moreover, developmental times were delayed and pupal weights were reduced for larvae fed Spondias purpurea leaves. Due to the broad host range exhibited by H. memor larvae, this species will not be considered as a biological control agent of S. terebinthifolia in the continental U.S.A.     

Reproductive properties of two sympatric dung beetles,Aphodius haroldianus andA. Elegans (Coleoptera: Scarabaeidae)

1. Reproductive properties of two sympatric dung beetles, Aphodius haroldianus and A. elegans, were studied at a pasture in the central Japan.
2. Overwintered adults of A. haroldianus came flying to dung pats from May to early August and bred from June to July. A. elegans overwintered as larvae, new adults came to dung pats from mid May to mid June. After aestivation, they reproduced from October to November.
3. A. haroldianus was a species with low fecundity and large food reserve for larvae. Female of this species had short duration of residence and laid fewer number of eggs in one dung pat. On the other hand, A. elegans was a species with high fecundity and small food reserve for larvae. Female of this species had long duration of residence and laid larger number of eggs in one dung pat.
4. The daily egg production in A. haroldianus reached a peak (0.40 eggs/female/day) at middle of oviposition period, but, that in A. elegans reached a peak (6.49 eggs/female/ day) at the beginning of oviposition period. The mortality of A. haroldianus female occurred after the daily egg production reached a peak and then rapidly increased, whereas that of A. elegans began soon after the beginning of oviposition and then gradually increased.

     

Effects of head shape variation on growth, metamorphosis and survivorship in larval salamanders (Hynobius retardatus)

The effects of head shape variation on growth and metamorphosis in larval salamander (Hynobius retardatus) were examined by a laboratory experiment and a field experiment. In the laboratory experiment, each larva was fed equal amounts and was prevented from accessing others in both the solitary and group treatments, although chemical cues could be transmitted through water in the group treatment. The relative head width of larvae became larger in the group treatment during the early periods but having a large head width did not finally influence growth rate and days for metamorphosis. In the field experiment, larvae were allowed to contact each other directly in two density conditions. The enlarged relative head width was linked to high growth rate in the high-density treatment but not in the low-density treatment. The larval body size distribution in the high-density condition tended to be smaller, and there was a small proportion of large-sized individuals with a broad head width. Moreover, the small number of large larvae metamorphosed much earlier than the others. The mortality of larvae in high-density conditions was much higher than that in the low-density treatments. This would be a consequence of cannibalism in the high-density condition. From the experimental results obtained, it is argued that for the larvae of H. retardatus having a large head is an adaptive tactic that maximizes fitness, particularly in temporary ponds with an unpredictable environment and in crowded conditions.     

Infection Status of Gnathostoma spinigerum Larvae in Asian Swamp Eels,Monopterus albus,Purchased from Local Markets in Cambodia

Present study was performed to know the infection status of Gnathostoma sp. larvae in swamp eels from Cambodia. We purchased total 30 Asian swamp eels, Monopterus albus, from local markets in Pursat and Takeo Provinces and Phnom Penh on May and November 2017 and May 2018. All collected eels were transferred to our laboratory with ice and each of them was examined by artificial digestion method. A total of 15 larval gnathostomes (1–5 larvae) were detected from 55.6% (5/9) swamp eels in Pursat Province. No larval gnathostomes were found in 21 swamp eels in Takeo Province and Phnom Penh. The advanced third-stage larvae (AdL₃) detected were 2.575–3.825 (3.250) mm in length and 0.375–0.425 (0.386) mm in width. They had the characteristic head bulb (av. 0.104×0.218 mm) with 4 rows of hooklets, long muscular esophagus (1.048 mm), and 2 pairs of cervical sacs (0.615 mm). The number of hooklets in 4 rows on the head bulb was 41, 44, 47, and 50. In scanning electron microscopy, characteristic features were 4 rows of hooklets on the head bulb, cervical papillae, tegumental spines regularly arranged in transverse striations, and anus. The larval gnathostomes were identified as AdL₃ of Gnathostoma spinigerum based on the morphological characters. By the present study, it has been confirmed that G. spinigerum larvae are infected in Asian swamp eels, M. albus, in Pursat Province, Cambodia.     

Larval abundance and recruitment of Carcinus maenas L. close to its southern geographic limit: a case of match and mismatch

In the Ria Formosa lagoon (S. Portugal), Carcinus maenas larvae have been observed only during the cold part of the year (October–May), when the water temperature stays below 23 °C. Larvae suffer high mortality during day time (about 80% during 6 h). Hence, they will only develop outside the lagoon, as proved by the observation of zoea I stages exclusively. Main recruitment starts in April, i.e. much later than the first larvae appear. Small crabs prefer Zostera noltii patches and colonize other sites when the carapace width exceeds about 5 mm. A reserve of some small crabs is found in Zostera noltii patches nearly all year round. It is postulated that one of the key factors for successful propagation of the species is a match between physiological reactions (here in particular temperature effect on reproductive cycle and larval release), and the ecological conditions for larval survival and recruitment, such as predator impact, food availability or currents.     

Effect of host age on life cycle and morphological characteristics of Glyptapanteles liparidis (Hymenoptera: Braconidae), a parasitoid of Acronicta rumicis (Lepidoptera: Noctuidae)

The life cycle of Glyptapanteles liparidis was 23.75 ± 1.26, 21.95 ± 2.44 and 20.83 ± 0.78 days when fed on the first, second and third instar larvae of Acronicta rumicis, respectively. Although insufficient numbers hindered statistical analysis, the life cycle of G. liparidis appeared to be shortest, 19 days, when fed on fourth instar larvae. The life cycle of G. liparidis tends to shorten as the larvae of A. rumicis fed upon are more advanced. The body length, forewing length and head capsule width of female G. liparidis fed on first instar larvae of A. rumicis were greater than those of males, while the antennae of males were longer than those of females. When fed on second instar larvae, there was no difference in body length and head capsule width between males and females, but the male antennae were longer than the female, and the female forewings were longer than the male. When fed on third instar larvae, there was no significant difference in head capsule width between the sexes, but female body length and forewing length were greater than the male, and the male antennae were longer than the female. On the whole, females were bigger than males in terms of body length and forewing length, while antennae of the males were longer than those of the females. There was no difference in head capsule width between males and females. Body length, antenna length, forewing length and head capsule width of male and female G. liparidis were relatively larger when fed on first instar larvae of A. rumicis than when fed on second and third instar larvae.     

Larval biology of butterflyfishes (Pisces,Chaetodontidae): what do we really know?

Synopsis Relatively little is known of the pelagic portion of the life history of butterflyfishes. Eggs are small (<1 mm), pelagic and hatch in less than 30 hours. Most species pass through a so-called tholichthys larval interval characterized by elaborate, distinctive head spination:Coradion larvae have different head spination. While older chaetodontid larvae can be identified by adult characters, young (preflexion) larvae generally cannot now be identified below family. In tropical plankton studies chaetodontid larvae averaged <0.1% of larvae captured, and occurred in 13% of samples. This rarity is a major hindrance to further work, but is not unexpected in view of adult abundance. Larvae of a few taxa are most abundant in shelf waters, but larvae of many chaetodontid taxa seem to be most abundant in oceanic waters. In either case, waters near reefs have the fewest chaetodontid larvae. Offshore maxima of larvae appear to exist a few kilometers seaward of Great Barrier Reef ribbon reefs. Chaetodontid larvae may prefer the upper portion of the water column. Both size and age at settlement vary widely within the family and the large genusChaetodon, and the latter varies widely within species. Average size at settlement is less than 20 mm and age is less than 40 days. No correlation was found between size and age at settlement. Behaviour and feeding of chaetodontid larvae are essentially unstudied. Chaetodontid larvae seem to be least abundant in winter. The implications of these conclusions are discussed and some suggestions for further research are made. In all areas more work is needed.     

Effects of host stage on the development of the facultative autoparasitoid Encarsia tricolor (Hymenoptera: Aphelinidae)

Encarsia tricolor is a facultative autoparasitoid of the glasshouse whitefly, Trialeurodes vaporariorum, with a potential in biological control. The rate of development, number of mature oocytes at emergence, number of ovarioles and size of the emerged adults were studied. Five nymphal instars (N1, N2, N3, N4, and pharate adult) of T. vaporariorum were used as hosts for the females. Female larvae and pupae of E. tricolor and Encarsia formosa were used as hosts for the males. Females developed faster when the egg was laid on N3 (18.0 days from egg to adult) and slower on N1 (22.3 days). Females were bigger when developing from N1 and N3 than from N4 and pharate adult. On emergence the mean number of mature oocytes was always small (0.8–2.6). Males developed faster and were smaller than females, and developed faster and were larger on larvae of E. formosa.     

Larvae of Diagramma pictum (Haemulidae) from Tosa Bay, Japan

Preflexion to postflexion larvae (2.1–8.0 mm) of Diagramma pictum (Haemulidae) occur in coastal Tosa Bay, Japan from May to September. They can be distinguished from the other haemulid larvae by head spination, location of anus, and melanophore patterns. Compared with larvae identified as the same species from Australia, there are significantly morphological differentiations between the two areas. Thus, these significant differences are likely a reflection of subspecific differences.     

External Morphology of Lophiosilurus alexandri Steindachner, 1876 during Early Stages of Development,and Its Implications for the Evolution of Pseudopimelodidae (Siluriformes)

Pseudopimelodidae are Neotropical catfishes characterized by having slightly to strongly depressed body in fully developed specimens. The largest species of the family with 500 mm SL, Lophiosilurus alexandri, experiences impressive changes in body shape during development, becoming extremely depressed when fully developed. Accordingly, Lophiosilurus alexandri is an ideal species to observe the morphological changes during ontogeny, and to seek solid interpretations on the polarity of characters. Specimens of distinct larval periods (yolk sac, flexion and postflexion; n = 186 specimens) and juvenile stages (n = 20) were analyzed. Changes in body shape, position of mouth and eye, morphology of fins and pigmentation were observed during the development of Lophiosilurus. Larvae (5.7–11.2 mm standard length) had pigmentation concentrated on the head and parts of body, eyes small and pigmented, short barbels, and well-developed finfold. Juveniles (15.9–28.1 mm standard length) had body shape similar to adult, with head depressed and bearing bony ridges, large mouth, dorsally-oriented eyes, small barbels and well-developed shoulder bulges (cleithral width). The greatest morphological changes in the development of L. alexandri occurred during the postflexion larval stage. Relative to standard length, measurements of snout length, head depth and body depth are smaller in juveniles than in larvae, but body width is larger. New interpretations on the phylogenetic characters related to these changes are provided in view of the two alternative hypotheses of the evolution of Pseudopimelodidae.     

Seasonal Occurrence and Morphological Measurements of Pine Sawyer,Monochamus saltuarius Adults (Coleoptera: Cerambycidae)

To investigate the seasonal occurrence of the pine sawyer, Monochamus saltuarius, its emergence rate was observed in pine log and Korean white pine log conditions after the logs were cut to a regular size and placed in a netted cage. Numerical measurement was also conducted for sex ratios, fresh weight, body length and width, head width, and length of adult antennae. In the Korean white pine logs, the first day of emergence occurred on May 2, the day of peak emergence observed on May 29, and the last day of emergence was on June 10. In the pine logs, the first day of emergence occurred on May 7, the day of peak emergence was observed on May 22, and the last day of emergence was on May 30. The period of seasonal occurrence observed for the pine logs was shorter than that of Korean white pine logs. Sex ratios were 0.58; the average fresh weights of males (331) and females (379) were 0.21 g and 0.23 g; body lengths were 17.6 mm and 18.4 mm; body widths were 5.47 and 5.81 mm; head widths were 3.30 mm and 3.42 mm; and antennal lengths were 40.28 mm and 26.40 mm, respectively. The ratio of the length of the antenna to the body length was measured to be 2.0 in males and 1.4 in females.     

The impact of Bt maize as a natal host on adult head capsule width in field populations of western corn rootworm

The success of the current resistance management plan for transgenic maize, Zea mays L. (Poaceae), targeting the rootworm complex hinges upon high rates of mating between resistant and susceptible beetles. However, differences in the fitness of adult beetles could result in assortative mating, which could, in turn, change the rate of resistance evolution. Adult head capsule widths of naturally occurring populations of western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), were examined in a variety of refuge configurations. Beetles were classified into treatments based on the hybrid – non‐Bt refuge or Bt maize targeting larval rootworms (hereafter Bt‐RW maize) – and location – proximity to other Bt‐RW or refuge plants – of the natal host plant. Treatments included the following: a refuge plant surrounded by other refuge plants, a refuge plant located near a Bt‐RW plant, a Bt‐RW plant surrounded by Bt‐RW plants, and a Bt‐RW plant located near a refuge plant. The mean head capsule width of males emerging from Bt‐RW plants was significantly smaller than the mean head capsule width of males emerging from refuge plants. These results indicate that males emerging from Bt‐RW maize plants may be exposed to sublethal doses of the Bt toxin as larvae. No differences were detected between females emerging from refuge plants compared with Bt‐RW plants. Overall mean head capsule width decreased as the season progressed, regardless of treatment. The diminished head capsule width of western corn rootworm males emerging from Bt‐RW maize may act to enhance resistance management, particularly in a seed mix refuge system.     

Notes on the biology of the Oriental amblyoponine ant Myopopone castanea: Queen‐worker dimorphism,worker polymorphism and larval hemolymph feeding by workers (Hymenoptera: Formicidae)

Queen‐worker dimorphism, worker polymorphism and worker behavior in the Oriental amblyoponine ant Myopopone castanea were studied. Queen body size was large (head width, 3.0 mm) with 24 to 32 ovarioles while workers showed a remarkable size variation in both body size (head width 1.48 to 2.18 mm) and ovariole number (6 to 22). Both head width and abdomen width showed allometric growth against thorax width. Workers performed larval hemolymph feeding as was described for Amblyopone silvestrii queens.     

Reproduction and sexual dimorphism in the viviparous lizard Sceloporus palaciosi (Squamata: Phrynosomatidae) from the Trans‐Mexican Volcanic Belt,Mexico

In this study, sexual dimorphism, reproductive cycles, litter size and offspring size of a population of the little‐known species Sceloporus palaciosi in central Mexico were analysed. Significant male‐biased sexual size dimorphism was recorded in snout–vent length (SVL), head length, head width, forearm length and tibia length. Both sexes showed asynchronous reproductive cycles, and males reached sexual maturity at a smaller SVL (33 mm) than females (37 mm). Testes volumes were small from January to February, testicular recrudescence began from March to June, and decreased in July, but increased again in August and September, followed by a second decrease from October to December. In females, vitellogenesis began from May until ovulation in December. Embryonic development extended from November to March, and a small number of females carried embryos through July. Mean litter size was 4.0 and was positively correlated with female SVL. The length of the reproductive period in S. palaciosi recorded in this study is longer than that recorded for other populations in other parts of this species range. Further studies are needed to clarify reproductive cycles in the other isolated populations of S. palaciosi, and then extended to other species and chromosome races in the Sceloporus grammicus complex.     

Condition and size of damselflies: a field study of food limitation

Summary Based on evidence from field manipulations, several authors have recently suggested that interference competition among larval odonates reduces individual growth rates and biomass by reducing foraging rates. This study was designed to test the effects of food shortage on condition (relative mass per unit head width) of larval Ischnura verticalis (Odonata: Coenagrionidae) under laboratory conditions and to use these results to estimate the degree of food shortage of larvae under naturally occurring field conditions. In the laboratory, there were marked differences in condition of larvae fed diets ranging from ad libitum feeding with worms to ad libitum feeding with Daphnia 1 day out of every 8. Condition of larvae collected from May through October from 17 different sites in southern Ontario indicated that, for most of the year, larvae had conditions similar to those fed ad libitum with Daphnia in the laboratory. There was no evidence that larval condition was related to population density. Condition of larvae in most sites during July was similar to that of larvae fed poor diets in the laboratory. It is unlikely that the low conditions were due to competition as there were no correlations with density across sites and population densities during July were at their lowest. Adult head widths showed a seasonal decline from mid June to the end of the flight season. There was no evidence that head widths were related to population density although there was some evidence that head widths of males were positively related to larval condition. My results do not support the hypothesis that competition is important in affecting foraging rates and subsequent development of larvae. Contrasts between my results and other studies may stem from difficulties with the interpretation of field experiments, that densities in my study may have been low due to fish predation, and/or that I. verticalis larvae are slow moving relative to other larvae and thus less likely to interact.     

The male and female first instar larvae of Anaphes victus and A. listronoti (Hymenoptera, Mymaridae)

 Anaphes victus and A. listronoti are two closely related species, respectively solitary and gregarious parasitoids of eggs of the carrot weevil Listronotus oregonensis (Coleoptera, Curculionidae). Both species are sympatric, and the regulation of super- and multiparasitism that occurs regularly in this host is done by larval fights between the mymariform first instar larvae. The morphology of both male and female first instar larvae of A. victus and A. listronoti is described using scanning electron microscopy. Both species have first instar larvae of the mymariform type and present sexual dimorphism. The main difference between the two species is that larvae of A. victus are clearly segmented while larvae of A. listronoti show no visible segmentation. Male larvae of both species have two types of perioral hooks, longer and less dense dorsal setae than females and developed undertail spines. Female larvae of both species have short abdominal setae. These morphological differences are discussed in the context of intra- and interspecific larval competition. Accepted: 25 May 1997