Effect of the number of parasitoid (Apanteles kariyai) eggs [Hym.: Braconidae] on the growth of host (Leucania separata) larvae [Lep.: Noctuidae]

The developmental interactions between a gregarious endoparasitoid,Apanteles kariyai Watanabe and its host,Leucania separata Walker, were investigated. The parasitoid laid more eggs in older hosts. Host size increased gradiently as the instar advanced, but the number of eggs laid per host did not increase accordingly. The net weight of the host was correlated positively with the number of eggs laid and with the total weight of parasitoids, especially in cases of parasitization at 3rd (5th-instar type), 4th and early 6th instar where the correlation was significant at 1% level. It follows therefore that the more parasitoids there are relative to their host size, the more they contribute to make the host size larger.     

Reciprocal host-parasite relations as exemplified byChrysomphalus aonidum [Homoptera: Diaspididae] andPteroptrix smithi [Hymenoptera: Aphelinidae]

The parasitePteroptrix smithi (Compere) prefers to oviposit in hosts (Chrysomphalus aonidum L.) that are at least 5 weeks old. Parasitization of two week old hosts is possible, but only few parasites reach maturity, and the developmental duration is lengthened by about one third. The sex ratio with both large and small hosts was usually 1∶2, whereas the average number of emerging parasites varied from 1.9 for 2 week old hosts to 3–4 for 5 week old ones. Non-ovipositing scales that are attacked by the parasite will fail to reproduce and ovipositing ones will only produce part of their potential progeny. Other externally observable changes in the young parasitized host include the formation of a thinner scale cover that differs in coloration and size from the normal one.     

Specificity among the Casuarinaceae in root nodulation byFrankia

Pure cultured isolates ofFrankia made from root nodules of plant species from among three genera of the host family Casuarinaceae were used in inoculation trials of seedlings grown in water culture. A large number of host species among the genera Allocasuarina, Casuarina and Gymnostoma from Australia, Papua New Guinea and other South Pacific Islands were tested. The most widely infectiveFrankia strains were CcI3 and AllI1; theFrankia strains with the narrowest host range within the Casuarinaceae were CcI2 and GpI1. Intrafamily cross-inoculations were uncommon. The most broadly receptive host species wasG. papuanum. For many species ofAllocasuarina tested, no infection by anyFrankia available for testing could be observed.     

Lagged Population Growth in a Termite Host Colony: Cause or Consequence of Inquilinism?

The presence of foreign organisms in the colonies of social insects could affect energy allocation to growth and reproduction of these hosts. Highly specialized invaders of such long-lived hosts, however, can be selected to be less harmful. After all, it pays for these symbionts to keep their host’s good health thereby prolonging cohabitation in the homeostatic environment of the termite colony. Here, we investigated such a hypothesis, focusing on populational parameters of a termite host sharing its nest with an obligatory termite inquiline. To this end, 19 natural colonies of Constrictotermes cyphergaster (Silvestri, 1901) (Termitidae: Nasutitermitinae) were sampled and the (i) number of individuals, (ii) proportion of soldier/workers in the colonies, and (iii) presence/absence of obligatory inquiline Inquilinitermes microcerus (Silvestri, 1901) (Termitidae: Termitinae) were measured. Results revealed a negative correlation between the number of individuals and the proportion of soldier/workers in the host colonies with the presence of I. microcerus colonies. In search of causal mechanisms for such a correlation, we inspected life history traits of both, inquilines and hosts, hypothesizing that such a result could indicate either (i) a dampening effect of the inquiline upon its host population or (ii) the coincidence of the moment of inquiline infiltration with the natural reduction of C. cyphergaster populational growth at the onset of its reproductive phase.     

The influence of wild and cultivatedGramineae andCyperaceae on populations of sugarcane borers and their parasites in North India

Sugarcane borers frequently inhabit wild and semi-cultivated grasses growing in the proximity of cane fields. In India, in view of the year-round cultivation of sugarcane, wild grasses are not necessary for the perpetuation of borer species, but observations indicate that certain borer species migrate from wild or other cultivated grasses to cane, thereby increasing levels of infestation in cane during certain seasons. Parasitism of borer species when present in cane is compared with that in wild or other cultivated grasses.Telenomus spp. amongst egg parasites andApanteles flavipes amongst larval parasites are striking examples of parasites which show preference for the same borer species when they occur on wild hosts than on cane, as indicated by the degrees of parasitism. It is concluded that though wild grasses do not as a rule constitute a threat to the cultivation of sugarcane, they could indirectly influence borer populations in cane, parasitism of borers and consequently the extent of damage to cane. This study also reveals thatA. flavipes is highly polyphagous, attacking a number of host species occurring on a wide variety of host plants. Despite its polyphagous nature, it has proved extremely successful againstDiatraea saccharalis in Barbados, which indicates a need for some rethinking on the use of polyphagous natural enemies in biological control programmes.     

Population dynamics ofTelenomus fariai [Hym.: Scelionidae], a parasite of chagas' disease vectors VIII. Morphological and ecological comparison between two allopatric populations under laboratory conditions

Telenomus fariai Lima ranges from Argentina and Chile to Mexico; some ecological parameters and morphological characters were compared between tropical (Costa Rica) and temperate (Argentina) populations, as reared on tropical and temperate hosts. The results of the 4 combinations between the 2 parasite populations and the 2 host species (Triatoma phyllosoma pallidipennis Stal) andTriatoma infestans Klug) [Hym.: Reduviidae] showed that only the parasite's geographical origin was statistically significant when evaluated through adult female life expectancy at time of emergence from the host, development time, total progeny per host per female 0–24 h old, and generation time. No difference was found between parasite populations with respect to total progeny per female and net reproductive rate. The morphometry proved statistically significant for all body measurements except the antennae.     

Phenological and reproductive responses of a semiarid shrub to pulsed watering

Climate models forecast the decrease in annual precipitation and more extreme events (i.e. fewer rainy days and longer drought periods between rainfall events) in Mediterranean ecosystems which may have important consequences for plant community dynamics. Water availability is the most limiting factor for plant performance in arid environments, where it is often highly pulsed, and discrete rainfall events interspersed with drought periods are the important components of the annual water supply. Therefore, relatively small changes in rainfall frequency can have strong effects on the plant communities. We tested the effects of fewer rain events on inflorescence and fruit phenology, and reproductive success of a Mediterranean shrub species from semiarid SE Spain in a glasshouse trial. We found that by changing patterns of water supply, we strongly altered soil drying cycles with consequences for Phagnalon saxatile life history. Inflorescence and fruit phenology were not affected, and no changes in the number of inflorescences, fruits or fruit set were recorded. However, individuals growing under lower rainfall frequency produced bigger shoots, and heavier fruits and seeds. Bigger fruits produced a higher number of seeds that were heavier and more viable and, therefore, produced more seedlings than plants growing in the control treatment. Higher reproductive success achieved by Phagnalon individuals under low watering frequency may have important consequences for community dynamics if larger but less frequent rain events lead to an increase in soil water availability: natural selection favours individuals making the greatest contribution to the next generation. Such advantages could change community composition, the spatial distribution of species and their interactions.     

Studies on the life cycle of Pallisentis nagpurensis Bhalerao, 1931 (Pallisentidae; Acanthocephala) parasitic in the fish Ophiocephalus striatus (Bloch)

The life cycle of Pallisentis nagpurensis involves the fish Ophiocephalus striatus as the final host and the copepod Cyclops strennus as the intermediate host. The embryonated eggs are adapted to float in water. The development of the acanthors up to the stage of infective acanthellae takes place in the haemocoel of the cyclops in 15–20 days. The juveniles develop to maturity in the intestine of the fish after about 50 days. Incompletely developed juveniles penetrate the intestinal wall adjacent to the liver and then encyst in the peripheral tissues of the liver. Cannibalism among the fish seems to help the establishment of the encysted worms for normal development within the intestine. The life-cycle of the worm is neatly geared to the feeding habits of the host fish. A number of transport hosts have also been observed. Study has also been made on the morphology of various developmental stages of the worm.     

Developmental interactions between the army wormLeucania separata [Lep.: Noctuidae] and its parasiteApanteles ruficrus [Hym.: Braconidae]

The developmental interactions between the gregarious endoparasitoidApanteles ruficrus Hal. and the army worm,Leucania separata Walker were investigated. The parasitoid preferred young host larvae and developed in 9.5 days irrespective of host age at the time of parasitization. The growth of parasitized host larvae were depressed. The net maximum weight of the host larva was positively correlated with the number of parasitoid eggs laid when the 2nd instar was parasitized. And when parasitizing in 2nd instar, the weight of parasitoid was negatively correlated with the number of eggs laid. The parasitoid has an ability to regulate the size of the host and the parasitoid itself according to the number of eggs laid when the host larva is very small.     

A New Record of a Host-Parasitoid Interaction: Hymenoepimecis veranii Lofredo & Penteado-Dias, 2009 (Hymenoptera: Ichneumonidae) Parasitizing Araneus orgaos Levi, 1991 (Araneae: Araneidae)

The genus Hymenoepimecis only occurs in the Neotropics. In some species of this genus, the larval stage modifies the behavior of the spider hosts, inducing then to construct a modified web. The wasp Hymenoepimecis veranii has been previously described as an ectoparasitoid of the spider Araneus omnicolor. This study provides detailed information about the natural history of the host-parasitoid interaction involving this wasp with a new host, the spider Araneus orgaos (Araneae: Araneidae), which occurs sympatrically with A. omnicolor.     

Population genetics of Anastrepha fraterculus (Diptera,Tephritidae) in different hosts: Genetic differentiation and heterozygosity

An allozymic survey of 11 populations of Anastrepha fraterculus Wied. (Diptera, Tephritidae) in 8 different hosts from the same orchard revealed very small levels of genetic distance (D = 0.002±0.001) between hosts. The data thus provide no evidence for host-dependent genetic differentiation. Low values of heterozygosity were observed (H = 0.050±0.28) and 6 loci out of 11 were monomorphic. Biological attributes of the species, such as its polyphagic regime, multivoltine pattern of reproduction, and seasonal changes in population size, are discussed in an attempt to explain the low variability.     

Feral pigs as hosts for Amblyomma sculptum (Acari: Ixodidae) populations in the Pantanal,Mato Grosso do Sul,Brazil

The Pantanal in Brazil is the largest floodplain of the world. This ecosystem, rich in wildlife, has a large feral pig population. Such a large host biomass must have a strong influence on the parasite fauna. In this work, we evaluated the role of feral pigs in the maintenance of Amblyomma sculptum (formerly Amblyomma cajennense), the most prevalent tick species in the Pantanal. Tick infestations were evaluated on 243 feral pigs and their environment. The suitability of domestic pigs, representing their feral relatives, to A. sculptum adults and nymphs was assessed experimentally. Tick infestation of feral pigs was strongly associated with that of the environment: 96 and 97 % of the ticks, respectively, were A. sculptum. The infestation prevalence on this host species was close to 90 % in the dry season and 100 % in the wet season and mean infestation intensity was above 30 ticks in both seasons. Suitability of pigs as hosts for A. sculptum was shown by the high proportion of nymphs and female ticks found engorging on captured feral pigs and adequate biological parameters displayed by ticks from experimental infestations of domestic pigs. Other tick species on feral pigs, albeit in much lower numbers, were Amblyomma parvum and Ornithodorus rostratus. Results show that feral pigs feed a high proportion of the A. sculptum adults and nymphs in their territories and should be a target for tick-borne diseases studies. This is particularly relevant to public health because all the main tick species found on feral pigs are aggressive to humans as well.     

Echinoparyphium elegans (Looss, 1899) (Digenea: Echinostomatidae): the life cycle and redescription of the adult with a revision of the 43-spined members of the genusEchinoparyphium

The adult morphology ofEchinoparyphium elegans is redescribed. The life cycle is described. The first intermediate host is the freshwater snail,Bulinus truncatus. This and other freshwater snails, such asBulinus globosus, Physa acuta and albinoBiomphalaria glabrata, serve as second intermediate hosts. Adult worms were obtained experimentally from canaries, chicks, pigeons and albino rats, but not from albino mice. The 43-spinedEchinoparyphium species with a collar spined arrangement 5-5-3-3-27,E. bioccalerouxi, E. ralphaudyi andE. combesi, are placed into synonymy withE. elegans after examination of the paratypes.     

Ability of a Generalist Seed Beetle to Colonize an Exotic Host: Effects of Host Plant Origin and Oviposition Host

The colonization of an exotic species by native herbivores is more likely to occur if that herbivore is a generalist. There is little information on the life-history mechanisms used by native generalist insects to colonize exotic hosts and how these mechanisms are affected by host properties. We examined the ability of the generalist seed beetle Stator limbatus Horn to colonize an exotic species. We compared its host preference, acceptability, performance, and egg size when ovipositing and developing on two native (Pithecellobium dulce (Roxb.) Benth and Senegalia riparia (Kunth)) and one exotic legume species (Leucaena leucocephala (Lam.)). We also analyzed the seed chemistry. We found that females recognize the exotic species as an unfavorable host for larval development and that they delayed oviposition and laid fewer and larger eggs on the exotic species than on the native species. Survivorship on the exotic host was 0%. Additionally, seeds of the native species contain five chemical compounds that are absent in the exotic species, and the exotic species contains three sterols, which are absent in the native legumes. Genetically based differences between beetles adapted to different hosts, plastic responses toward new hosts, and chemical differences among seeds are important in host colonization and recognition of the exotic host. In conclusion, the generalist nature of S. limbatus does not influence its ability to colonize L. leucocephala. Explanations for the colonization of exotic hosts by generalist native species and for the success of invasive species must be complemented with studies measuring local adaptation and plasticity.     

Molluscicidal activity of the Puerto Rican Weed,Solatium nodiflorum,against snail hosts ofFasciola hepatica

After screening 200 species of Puerto Rican plants, Solanum nodiflorumwas selected for comprehensive laboratory evaluation as a source of natural molluscicide. All parts of this plant were found toxic to the snails Fossaria (Lymnaea) cubensis, Lymnaea columella, Biomphalaria glabrata,and Physa cubensis.No toxicity was found against Marisa cornuarietisand Tarebia granifera. The toxicant was not affected by pH and dry storage. There was a direct correlation between temperature and molluscicidal activity. The plant is easy to find locally and could be developed into cheap, safe means for controlling both Schistosomaand Fasciolasnail hosts in Puerto Rico.     

Plant and animal communities in brackish supra-littoral pools (‘dobben’) in the northern part of the Netherlands

Fifty brackish supra-littoral pools bordering the Waddenzee were studied. The structure of plant communities (Potamogeton pectinatus L., Ranunculus baudotii Godr. and Zannichellia pedunculata Rchb.) is discussed in relation to water level fluctuations, chlorinity and water transparency. Chlorinity tolerances of the macrophytes (7 species) are discussed. The macrofauna was studied semi-quantitatively. The aquatic Coleoptera had the greatest diversity (24 species). A distinct relationship between the number of Coleoptera species and the percentage of macrophyte coverage was found. The distribution patterns of the most frequent species with respect to chlorinity categories are shown in histograms. The number of aquatic Heteroptera species is also discussed in relation to chlorinity and vegetation coverage. Less important macrofaunal groups (the Crustacea, Mollusca and Odonata) occurred in low species numbers.     

The diversity of endophytic fungi in the above-ground tissue of two Lycopodium species in Poland

Endophytes are a large and diverse group of fungi that colonize healthy plant tissues without causing any symptoms. The majority of studies have focused on angiosperm and conifer hosts and few have examined the endophytes of lycophytes. In the present study, we characterized culturable endophytic fungi in two closely related Lycopodium species (L. annotinum and L. clavatum) from pine, beech, oak and spruce forests across Poland. More than 400 strains were isolated but only 18 Ascomycete species were identified. Members of the Dothideomycetes dominated the fungal endophyte communities in Lycopodium. The most abundant taxa cultured were Phoma brasiliensis (from L. clavatum) and Paraconiothyrium lycopodinum (from L. annotinum). Five taxa were isolated exclusively from L. annotinum, but only two of them (Paraconiothyrium lycopodinum and Mycosphaerella sp.) were relatively abundant. Two taxa were only found in L. clavatum, namely: Stagonospora pseudovitensis and an unidentified Dothideomycete. The taxon assigned as Ascomycota 2 (SH219457.06FU) was isolated only from strobili of both host species. Direct PCR and cloning from L. annotinum shoots revealed a substantially greater endophyte richness compared with the results from culturing.