Ecology of the biting midge Leptoconops albiventris in French Polynesia. III. Influence of abiotic factors on breeding sites. Towards ecological control?

Abstract. Correspondance Analysis was used to determine the significant abiotic factors influencing the ecology of the immature stages of Leptoconops albiventris (Diptera: Ceratopogonidae). The breeding places required strict environmental conditions: fine and well-sorted sand, with low conductivity and humidity. However, the microdistribution of the immature stages within a breeding site does not depend on such factors. Modifying physical parameters in the larval breeding areas might be an important component in future ecological control programmes against L.albiventris populations.     

Antipredatory Activity of the Weevil Oxyops vitiosa: A Biological Control Agent of Melaleuca quinquenervia

The larvae of the leaf-feeding weevil Oxyops vitiosa, a biological control agent of Melaleuca quinquenervia, are covered with a viscous orange coating that is thought to protect against generalist predators. This coating is gradually lost as the larvae drop to the ground and pupate in subterranean pupal cells. To test the antipredator activity of this species, four immature life stages (early instars, late instars, prepupae, pupae) were exposed to a common generalist predator, the red imported fire ant Solenopsis invicta. Choice tests were conducted by placing an O. vitiosa individual and a control larva of the weevil Neochetina eichhorniae into an arena containing a S. invicta colony and observing subsequent ant behaviors. S. invicta workers contacted O. vitiosa early instars, late instars, and prepupae less frequently than control N. eichhorniae larvae, and upon contact S. invicta was less likely to behave aggressively toward these O. vitiosa life stages than toward N. eichhorniae larvae. However, S. invicta contacted, attacked, and consumed naked (nonencased) O. vitiosa pupae and N. eichhorniae larvae with equal frequency. Encased O. vitiosa pupae buried in sand were not attacked compared to susceptible encased pupae on the sand surface. By shifting from a chemical defense during the larval stages to a physical defense during the pupal stage, O. vitiosa reduces the risk of attack by this generalist predator.     

Taxonomy of the New Zealand genus Eulimnia,and biology and immature stages of E. philpotti (Diptera: Sciomyzidae)

Abstract

The endemic New Zealand genus Eulimnia and its two species are redescribed. Data are presented on the life cycle of E. philpotti Tonnoir & Malloch, and the habitat, geographical distribution, phenology, and biological features of adults and immature stages are discussed. Adults are found in permanently wet marshes, where the larvae prey on fingernail clams (Bivalvia: Sphaeriidae) while completely submerged. Mature larvae form puparia among vegetation or debris above the water level. The immature stages of E. philpotti are described. The genus is placed in tribe Tetanocerini, and its taxonomic position is discussed.     

Life-cycle and host specificity of Amblyomma tigrinum (Acari: Ixodidae) under laboratory conditions

Biological data of three generations of Amblyomma tigrinum in the laboratory are reported and the suitability of different host species for immature ticks are compared. Grouping the three generations, infestations by both the larval and nymphal stages were performed on chickens (Gallus gallus), wistar rats (Rattus norvegicus), rabbits (Oryctolagus cuniculus),wild mice (Calomys callosus), dogs (Canis familiaris) and opossums (Didelphis albiventris). Only dogs were used for infestations by adult ticks. Tick developmental periods were observed in an incubator at 27°C and RH 90%. The proportion of engorged larvae recovered from chickens (21.7% of the exposed larvae) was significantly larger (p<0.001) than those from the five mammal species used in the infestations (maximum of 3.1%). A significant larger (p<0.01) proportion of engorged larvae successfully molted after being fed on chickens than on mammal hosts. The proportion of engorged nymphs recovered from chickens (28.8% of the exposed nymphs) was significantly larger (p<0.001) than those from mammal hosts (range: 0–2.1%). Larvae showed similar feeding periods on exposure to different host species, except for those larvae fed on C. callosus, which showed significantly longer (p<0.001) feeding periods. Engorged larvae detachment peaked on the 5^th feeding day, followed by the 6^th day, on all hosts except for C. callosus. Larval premolt periods were similar for engorged ticks exposed to different host species, except for larvae fed on dogs, which showed significantly longer (p<0.001) premolt periods. Host detachment of engorged nymphs peaked on the 6^th feeding day on chickens. Although nymphal detachment on rats peaked on the 8^th day, only 15 nymphs were recovered from this host species. In a sample of 144 F₃ nymphs fed on chickens no significant difference (p>0.10) was found between the feeding or premolt periods of 82 males and 62 females, but female nymphs were significantly heavier (p<0.005) than male nymphs. Sixteen engorged females (61.5% of the exposed ticks) were recovered after being fed on dogs, and all these females laid viable eggs. Chickens, the only avian host, were the most suitable host when compared with the five mammal species. Dogs were demonstrated to be a suitable host for adults of A. tigrinum, which is consistent with, several reports of adult A. tigrinum ticks parasitizing dogs in different areas of South America. Our results reinforce that in these same areas avian species are the major hosts for immature stages of this tick species. This revised version was published online in July 2006 with corrections to the Cover Date.     

Submergence tolerance in immature stages of the stalk-eyed fly Sphyracephala detrahens (Diptera: Diopsidae)

Sphyracephala detrahens (Walker, 1860) (Diptera: Diopsidae) inhabits the riparian zones of streams and rivers. Because of the limited dispersal ability of S. detrahens during egg, larval, and pupal stages, immature individuals are at risk of being submerged by floodwater after heavy rain. In this study, I evaluated the submergence tolerances of immatures of S. detrahens by comparing them to immatures of Drosophila melanogaster, which also feed on rotten fruits but are not restricted to the riparian zone. The results showed that S. detrahens eggs were susceptible to desiccation, but more than 80% of eggs hatched after full submergence. Later instar larvae were more resistant to full submergence than earlier instar larvae. The duration of submergence causing 50% pupation (PD₅₀) in the first, second, and third-instar larvae of S. detrahens were 15.88, 58.46, and 91.74 h, respectively. The PD₅₀ of the third-instar larvae of D. melanogaster was 20.01 h. Third-instar S. detrahens larvae continued to develop in water for a longer duration than D. melanogaster larvae of the same instar. In the pupal stages, late pupae tended to remain afloat longer than early pupae. The duration of submergence causing 50% emergence (ED₅₀) of adults from early and late pupae were 40.70 and 104.74 h, respectively. In the larval and pupal stages, individuals in the later developmental phases tended to be more tolerant to full submergence. The submergence tolerance of the immature stages of S. detrahens may reflect adaptation to an environment with fluctuating water levels.     

Fungivory of Anatatha lignea, an interesting habit in Noctuidae (Lepidoptera)

The larvae of Anatatha lignea (Butler) were found consuming the brown surface of synthetic logs on which the shiitake mushroom, Lentinula edodes (Berk.) Pegler, formed a thick mycelial coat. Fungivory has been rarely reported in the Noctuidae, and this is the first record of fungivory from the genus Anatatha. The female genitalia and the immature stages of A. lignea are illustrated and described for the first time. Its lectotype is designated and illustrated, and details of the species’ biology is given. The female genitalia of A. misae Sugi, a species closely related to A. lignea, are illustrated and described for the first time.     

Host-parasite association between <Emphasis Type="Italic">Didelphis albiventris</Emphasis> (Didelphimorphia: Didelphidae) and <Emphasis Type="Italic">Ixodes loricatus</Emphasis> (Acari: Ixodidae) in their southern ranges

The parasitism of Ixodes loricatus Neumann on white-eared opposum, Didelphis albiventris Lund, was analysed in the southern ranges of both. In central Argentina, 118 wild opossums were captured from 2005 to 2012. Adults of I. loricatus were collected (prevalence?=?66.1%, mean?=?7.03, median?=?4), but no immature stage. Tick infestation was not affected by sex (p?=?0.27) or age (p?=?0.37) of hosts. In line with previous studies about seasonality of larvae and nymphs of I. loricatus, adult tick infestation showed no seasonal trend. This lack of seasonal pattern of infestation for all parasitic stages of I. loricatus may indicate a life cycle governed by nidicolous behaviour, in such a way that this habit would contribute to minimize the influence of external environmental variables. The tick sex ratio was female biased, with two females per one male (p?=?0.002). The absence of I. loricatus immatures on D. albiventris suggests that in the study region there is clear segregation of immatures in rodents and adults in marsupials.     

Abiotic factors affecting the infectivity of Steinernema carpocapsae (Rhabditida: Steinernematidae) on larvae of Anastrepha obliqua (Diptera: Tephritidae)

The effects of soil depth, soil type and temperature on the activity of the nematode Steinernema carpocapsae (Filipjev) were examined using larvae of the West Indian fruit fly, Anastrepha obliqua (Macquart). Bioassays involved applying infective juveniles (IJs) to the surface of sterilized sand in PVC tubes previously inoculated with fly larvae of two ages. The 50% lethal concentration (LC₅₀) values estimated for 6-day-old larvae were 9, 20 and 102 IJs/cm² in tubes containing 2, 5 and 8 cm depth of sand, respectively, whereas for 8-day-old larvae, LC₅₀ values were 16, 40 and 157 IJs/cm², respectively. The effect of soil texture on the activity of S. carpocapsae was tested by applying the corresponding LC₅₀ concentrations of nematodes to sand, sand–clay and loamy–sand soils. For 6-day-old larvae, soil type had a highly significant effect on infection with the highest percentages of infection observed in the sand–clay mixture (60–82% depending on depth) compared to 45–64% infection in sand and 23–30% infection in loamy–sand soil. A very similar pattern was observed in 8-day-old larvae except that infection rates were significantly lower than in younger larvae. There was a significant interaction between soil type and soil depth. The effect of three temperatures (19, 25 and 30°C) on infection was examined in sand–clay soil. The infectivity of S. carpocapsae was affected by temperature and soil depth and by the interaction of these two factors. Response surface analysis applied to second order multiple linear regression models indicated that the optimal temperature for infection of larvae of both ages was ~26°C, at a depth of 7.9 cm for 6-day-old larvae and <2 cm for 8-day-old larvae, resulting in a predicted 91.4% infection of 6-day-old larvae and 61.2% infection of 8-day-old larvae. These results suggest that S. carpocapsae may have the potential to control fruit fly pests in tropical ecosystems with warm temperatures and high soil moisture levels, although this assertion requires field testing.     

Beauveria bassiana affects immature stage development of Prostephanus truncatus (Coleoptera: bostrichidae) in stored maize

Recent research in Ghana has demonstrated the effectiveness of an isolate of B. bassiana, sensu lato (IMI 389521) from the U.K. against the larger grain borer Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae), a major pest of stored maize. To determine whether this isolate is effective on immature stages of P. truncatus, a laboratory study of the response of immature stages (egg, larvae and pupae) of P. truncatus in maize grains to two concentrations (1?×?10⁹ and 3.16?×?10⁹?cfu/kg maize) of B. bassiana, IMI 389521 formulated with Entostat? and kaolinite was undertaken. Adult emergence, per cent survival of adults that emerged and the number of larvae in each immature stage were assessed after 45 days. Apart from the egg experiment, higher numbers of adults emerged in grains containing larvae and pupae treated with B. bassiana product compared to the untreated maize control. This notwithstanding, survival of emerged adults of P. truncatus was greatly reduced in B. bassiana treatments (<10%) compared with 75–95% in the controls. Surface treatment with B. bassiana on pre-infested maize showed a significant effect on the developmental biology of P. truncatus in Ghana.     

Selectivity evaluation of insecticides used to control tomato pests to Trichogramma pretiosum

The effects of the insecticides abamectin, acetamiprid, cartap and chlorpyrifos on larvae, pupae (within the host egg) and adults of the egg parasitoid Trichogramma pretiosum Riley (Hym.: Trichogrammatidae) were evaluated under laboratory conditions, using three standard tests described by IOBC. When sprayed on the immature stages of this parasitoid, cartap and chlorpyrifos proved to be the most harmful insecticides, affecting both the emergence success and parasitism capacity of this parasitoid, whereas abamectin and acetamiprid were selective. Abamectin was harmful to adults (residue test on glass plates), slightly harmful to larvae, and moderately harmful to pupae (sprayed on the immature stages within host eggs Anagasta kuehniella (Zeller)); acetamiprid was moderately harmful to adults, harmless to larvae, and slightly harmful to pupae; cartap was harmful to adults, moderately harmful to larvae and harmful to pupae; chlorpyrifos to adults, harmless to larvae and harmful to pupae.     

New records of tree roosts of Noctilio albiventris from the Pantanal,Brazil

The selection of roosts is considered a critical factor to the survival of Noctilio albiventris. Thus, we located and identified N. albiventris day roosts in the Pantanal, near the Miranda River. We identified four species of tree: Banara arguta, Inga vera, Ocotea diospyrifolia and Vitex cymosa. Additional studies are important to understand the impact of specific requirements in the selection of roosts for Noctilio albiventris and to compare the observed patterns in different environments.     

Feeding habits of sand smelt (Atherina boyeri, Risso 1810) in Trichonis Lake (Western Greece)

The feeding habits of sand smelt (Atherina boyeri, Risso, 1810) from Trichonis Lake (Western Greece) were investigated. Stomach contents were analyzed from 240 specimens with total lengths ranging from 35 to 112 mm. Samples were taken at monthly intervals (January–December 1997). Of the total number of stomachs examined, 53 were empty (22.1%). However, values varied greatly with season (maximum in January: 50%; minimum in August: 7.6%). Prey analyses of stomach contents identified 15 important items (%Rn > 0.05) belonging to six major groups: crustacean (copepods, cladocera), mollusca (bivalve: larvae), insects (larvae), cestode worms and finfish (fry and eggs). Dominant prey were larvae of the bivalve Dreissena polymorpha (%Rn = 33.8), the copepods Eudiadomus drieschi (%Rn = 26.4) and the cladocera Diaphanosoma brachyurum (%Rn = 24.2). The importance of cladocera and copepods decreased with increasing size of the sand smelt, while the importance of bivalve larvae, fish eggs and finfish fry increased with increasing sand smelt size. Seasonal changes in diet composition and prey abundance in sand smelt stomachs were recorded as coinciding with the seasonal composition and abundance of the zooplankton community in the surface layers of Trichonis Lake. Bivalve larvae were the dominant prey of A. boyeri during January to May, while copepods and cladocera dominated from June to December.     

Hosts,distribution and genetic divergence (16S rDNA) of <Emphasis Type="Italic">Amblyomma dubitatum</Emphasis> (Acari: Ixodidae)

We supply information about hosts and distribution of Amblyomma dubitatum. In addition, we carry out an analysis of genetic divergence among specimens of A. dubitatum from different localities and with respect to other Neotropical Amblyomma species, using sequences of 16S rDNA gene. Although specimens of A. dubitatum were collected on several mammal species as cattle horse, Tapirus terrestris, Mazama gouazoubira, Tayassu pecari, Sus scrofa, Cerdocyon thous, Myocastor coypus, Allouata caraya, Glossophaga soricina and man, most records of immature and adult stages of A. dubitatum were made on Hydrochoerus hydrochaeris, making this rodent the principal host for all parasitic stages of this ticks. Cricetidae rodents (Lundomys molitor, Scapteromys tumidus), opossums (Didelphis albiventris) and vizcacha (Lagostomus maximus) also were recorded as hosts for immature stages. All findings of A. dubitatum correspond to localities of Argentina, Brazil, Paraguay and Uruguay, and they were concentrated in the Biogeographical provinces of Pampa, Chaco, Cerrado, Brazilian Atlantic Forest, Parana Forest and Araucaria angustifolia Forest. The distribution of A. dubitatum is narrower than that of its principal host, therefore environmental variables rather than hosts determine the distributional ranges of this tick. The intraspecific genetic divergence among 16S rDNA sequences of A. dubitatum ticks collected in different localities from Argentina, Brazil and Uruguay was in all cases lower than 0.8%, whereas the differences with the remaining Amblyomma species included in the analysis were always bigger than 6.8%. Thus, the taxonomic status of A. dubitatum along its distribution appears to be certain at the specific level.     

Susceptibility of Megalurothrips sjostedti developmental stages to Metarhizium anisopliae and the effects of infection on feeding, adult fecundity, egg fertility and longevity

The susceptibility of immature stages of the legume flower thrips, Megalurothrips sjostedti, to the entomopathogenic fungus Metarhizium anisopliae, was investigated under laboratory conditions. The adult stage was found to be more susceptible to infection than the larval and pupal stages. Mortality at all stages was dose-dependent, with the highest concentration of 1×10⁸ conidia ml^–1 producing the highest mortality (26, 46 and 100% for larvae, pupae and adults, respectively) at 8 days post-inoculation. At the same concentration, daily pollen consumption was significantly reduced at 2 days after treatment in infected adults but more slowly in infected larvae. Fecundity, egg fertility and longevity in adults surviving infection as larvae were significantly reduced compared to the control.     

Amphibians as definitive hosts for pentastomids: Raillietiella bufonis n.sp. from Bufo lemur in Puerto Rico and a reassessment of Raillietiella indica Gedoelst, 1921

Summary A new species of a cephalobaenid pentastomid infecting the lungs of a toad, Bufo lemur, from Puerto Rico is described. The single infection comprises all stages from infective larvae to mature males and females and therefore we consider the toad to be a definitive host. We reassess the evidence concerning Raillietiella indica Gedoelst, 1921, another raillietiellid from the lungs of an Indian toad, B. melanostictus which, hitherto, has been considered by most authors an immature stage from an intermediate host. It now appears that the type specimen was probably a gravid female and that R. indica is a valid species which also matures in a toad. Thus amphibians are established as a new class of definitive hosts for pentastomids. ac]19820218     

SEX RATIO AND AGE STRUCTURE OF GAMASID MITES FROM SMALL MAMMALS IN WESTERN YUNNAN,CHINA*

Abstract A total of 70 species of gamasid mites (7485 individuals) were collected from the body surface of 38 species of small mammals (3023 individuals) during an investigation of 13 counties of western Yunnan, China, from 1990 to 1996. Most species of gamasid mites have more females (80% 100%) than males (P <0.01). Exceptions are Haemogamasus gongshanensis where males outnumber females (P < 0.01) and Haemolaelaps glasgowi where there are similar numbers of males and females (P > 0.05). No larva was found in most of the mite species. The proportion of individuals at the immature stages (mainly protonymphs and deutonymphs) in most mite species is small (0–12.84%) compared to the adults (P < 0.01). Exceptions are Ornithonyssus bacoti and Haemolaelaps glasgowi where 62.84% and 49.48% respectively are nymphs. The biased sex ratios may reflect the probable different bloodsucking preferences and parthenogenesis of the gamasid mites. The absence of larvae and a low proportion of nymph stages in most mite species probably reflect that the larvae or nymphs of most mite species are non‐feeding or non‐blood sucking and are in their hosts' nests. Another possibility is that some species directly produce protonymphs or even deutonymphs without eggs and larvae which makes it difficult to find the larval stage.     

Morpho-Ecological Characteristics of Immature Stages of Xylobiont Species of the Genus Phaonia Robineau-Desvoidy, 1830 (Muscidae,Diptera) Inhabiting Tree Holes and Sap Accumulations

The biology of immature stages of the Diptera that accompany xylophagous insects inhabiting sap runs and tree holes was studied. Biological data are reported for the first time for 4 species and supplemented for 2 more species of the genus Phaonia Robineau-Desvoidy, 1830 (Muscidae). The main diagnostic characters of these species are given. The species differ in the life history of larvae, the morphology of the anterior and posterior spiracles, creeping welts, cephalopharyngeal apparatus, and anal plate. A key to immature stages of xylobiont species of the genus Phaonia is compiled.

     

Larval retention and dynamics of the prawns Palaemon longirostris H. Milne Edwards and Crangon crangon Linnaeus (Decapoda,Caridea) in the Mira estuary,Portugal

Summary

Palaemon longirostris and Crangon crangon larval and post-larval stages were collected intensively in two 24-h cycles during neap and spring tidal periods in a fixed station located in the mid-Mira estuary (southwest Portugal). In each case, on the previous day, horizontal distribution of larval stages was studied in a series of 20 stations from the mouth of the estuary to near freshwater. Horizontal distribution of the discrete instars of both species were similar, suggesting larval retention. Results from the 24-h cycles indicate a semilunar cycle of larval release activity, and an initial displacement of the larvae from the parental stock, as newly-hatched larvae concentrate in the surface layer of the water column on post-crepuscular ebbing tides. The sequence of larval stages tends to be progressively more dependent of the bottom layers, and the whole larval and post-larval development is accomplished within the estuarine boundaries. Larval release cycles, coupled with duration of development and progressive change in vertical position, induce mutual exclusion of different aged larvae, which may minimise cannibalistic behaviour and competition between larvae with different capabilities.