Insect herbivores and their natural enemies in the mangals of the Andaman and Nicobar islands

The mangroves of the Andaman and Nicobar Islands were extensively surveyed for their insect herbivore—natural enemy complex. A total of 197 species of herbivores, 43 species of hymenopterous parasitoids and 36 species of predators were found in the mangals of these islands. This forms the most extensive listing of herbivorous insects definitely associated with mangroves in the Indian region. In addition to some species that are probably mangrove specialists we have found some serious pests of crop plants which utilise various species of mangroves as alternative host plants. We also present consolidated lists of the insect phytophages so far recorded from the mangals of the Andaman and Nicobar Islands and mainland India.     

A note on the entomofauna of mangrove associates in the Andaman Islands (Indian Ocean: India)

The mangals of South Andaman Island were surveyed for the insect fauna of mangrove associates. The herbivorous insects collected were reared to adulthood on the hosts on which they were collected. The parasitoids that emerged during the rearings were also collected. Ninety‐six species of insect herbivores and nine species of hymenopteran parasitoids were collected during this study. Comparison with insects known to be phytophagous on true mangroves indicated that species overlap between insects on true mangroves and those on mangrove associates was minimal. Each of these plant communities apparently has its own distinct entomofaunal complex.     

The armoured scale insects (Homoptera: Diaspididae) of avocado trees in Israel

Summary

Seven species of armoured scale insects infest avocado in Israel. Hemiberlesia lataniae (Signoret) and Abgrallaspis cyanophylli (Signoret) are the most abundant. Avocado seedlings become infested in the nurseries, thus serving as important sources for commercial grove contamination. Because larger diaspidid populations develop at the inside of the trees (as compared to their outside), and at height levels of 1·5–2·0 m (compared to 5·0–6·0 m), these regions were regularly sampled. Equal-area examinations of bark and leaf revealed that H. lataniae prefers the bark, A. cyanophylli the leaves. The populations of both scales undergo similar annual cycles on leaves, peaking during winter, ebbing in early summer. The specific settling pattern of most diaspidids on avocado leaves were figured. The somewhat-different settling sites of H. lataniae and A. cyanophylli apparently preclude competition when low numbers are present, but the former may be partially inhibited when large populations develop. Several predators and hymenopterous parasitoids attack the diaspidids, the parasitoids being most active in early summer. No economic injury to local avocado fruit by armoured scale insects has been reported in recent years. The reasons for this are discussed, and it is recommended that the present situation, in which no insecticides are used in avocado groves, be maintained.     

Diet comparison between rainforest and cave populations of Craugastor alfredi (Anura: Craugastoridae): does diet vary in contrasting habitats?

Information about interpopulational variation of diet is important for thoroughly understanding the ecological niche of a species, the possible attributes that have allowed it to live in different habitats and ecosystems (if it is the case) and the degree of dietary specialization. This study compared dietary composition and diversity, size of prey consumed and feeding intensity between two geographically proximate populations of Craugastor alfredi, inhabiting contrasting habitats: one located in a remnant tropical rainforest and the other population located within a cave entrance, in eastern Mexico. A total of 118 frogs (50 from rainforest and 68 from cave) were stomach-flushed and, from those, 86 had at least one prey item (42 from rainforest and 44 from cave). Consumption proportions of orthopterans differed between habitats, with frogs from the cave having higher importance values of this prey than frogs from the rainforest. Additionally, both dietary diversity and feeding intensity were higher in the rainforest population. It was concluded that the generalized diet of C. alfredi, besides the high consumption of orthopterans by the cave population, may have contributed to its success in cave entrances. Nonetheless, other non-feeding attributes like small body size, direct development and semiarboreality may also facilitate the use of rock crevices in caves for foraging and reproduction.     

Generalist hymenopteran parasitoids of the leaf-miner Chromatomyia fuscula (Zett.) (Dipt.: Agromyzidae)

In southeastern Norway, by the last week of June (1992), 48%of Chromatomyia fuscula emerged, based on the number of mines collected from Hordeum vulgare leaves. Among the parasitoids Diglyphus begini was the dominant species, but Cirrospilus vittatus and Neochrysocharis aratus also emerged in significant numbers. During June and July, N. aratus was the dominant species in the 1st and 2nd leaves, but D. begini was dominant in the 4th to 6th leaves. C. vittatus and Cyrtogaster vulgaris affected all larvae of the leaf-miner fly, living on various leaves. In central Norway, 48% of C. fuscula also emerged. C. vulgaris and D. begini were the dominant parasitoids and C. vittatus was also found. C. fuscula has no specialist parasitoids. Adults of the generalist parasitoids of the leafminers always search for different hosts. In investigation of the parasitoid complex of a lepidopteran leaf-miner, Phyllocnistis labyrinthella (living in Populus tremula leaves at the edge of the examined barley field), three shared parasitoids (C. vittatus, Pnigalio soemius and Pnigalio pectinicornis) were found. The complex network of host plant-phytophagous insect-insect parasitoid-facultative hyperparasitoid relationship is discussed.     

Within‐nest abundance of a tropical cockroach Pseudoanaplectinia yumotoi associated with Crematogaster ants inhabiting epiphytic fern domatia in a Bornean dipterocarp forest

Many epiphytic ferns in tropical forest canopies have domatia that provide habitat for arboreal arthropods such as ants. Two species of fern that were predominantly occupied by Crematogaster difformis ants were collected from the canopy of a forest in Borneo. In the fern domatia, two cockroach species, Pseudoanaplectinia yumotoi and Blatta sp., were found to live with C. difformis. Pseudoanaplectinia yumotoi were found in large numbers and accounted for approximately 20% of the total arthropod population, while Blatta sp. comprised only 1% of the arthropods living in the domatia. Behavioural experiments were conducted to evaluate the response of C. difformis workers to newly introduced cockroaches of each species and to allospecific ant workers. Crematogaster difformis workers were highly aggressive and quickly attacked allospecific workers. Both cockroach species could fend off ant attacks; however, dead Blatta sp. were often attacked by the ants while dead P. yumotoi were infrequently bothered.     

Female treehoppers camouflage behaviour is evidenced during oviposition on wild shrubs

Various species of treehoppers possess a structure known as ‘helmet’ that may work as a camouflage feature (i.e. masquerade) by mimicking plant thorns. The helmet is expected to provide an adaptive advantage against predators if treehoppers choose to stay closer to thorns during times of vulnerability. The treehopper Enchenopa brasiliensis Strümpel possess a helmet that visually resembles the leaf thorns of its host plant, the wolf apple shrub Solanum lycocarpum St. Hill. In a field study, I examined the hypothesis that females of E. brasiliensis exhibit a potential camouflage behaviour by choosing to oviposit next to leaf thorns of S. lycocarpum. In fact, the results reveal that females of E. brasiliensis preferred to oviposit mostly on leaf midribs of S. lycocarpum possessing thorns as opposed to those without thorns. Additionally, females preferred to lay eggs closer to larger clusters of midrib thorns. This finding suggests that this oviposition/camouflage behaviour will likely increase the chances of female treehoppers being misidentified by predators; therefore, characterizing the mechanism of masquerade/deceptive resemblance. In a broader sense, this study also provides further evidence on how the narrow ecological relationships between plants and specialist herbivores can fuel the evolution of specific behavioural adaptations.     

Arthropods associated with nests of Cacicus sp. and Psarocolius sp. (Passerida: Icteridae) in varzea forest near the meeting of the rivers Negro and Solimões (Central Amazonia,Brazil) at high water

We analysed the arthropod fauna from nine nests of Cacicus sp. and nine nests of Psarocolius sp. (Passerida: Icteridae), in the varzea forest of Central Amazonia, Brazil, during high water, establishing these nests as one of the probable refuges for several arthropods performing vertical migration during periods of flooding and high water, besides discussing the role of these arthropods in the nests. We also evaluate the effectiveness of the extraction of arthropods from nests using an apparatus based on the Berlese–Tullgren funnel. We obtained 15,128 arthropods from three subphyla, five classes and 16 orders. The nests were shown as complex ecosystems sheltering groups from different functional and trophic categories and revealed striking differences from those of terra firma, remarkably in Blattaria, Arachnida and Pseudoscorpiones. The increasing volume of the funnel and time of heat exposure was shown to be appropriate for extraction of the arthropods from the bulky nests of these birds.     

Foraging ecology of the giant Amazonian ant Dinoponera gigantea (Hymenoptera,Formicidae, Ponerinae): activity schedule,diet and spatial foraging patterns

This study provides a detailed account of the natural history and foraging biology of the ponerine ant Dinoponera gigantea in a rainforest in north Brazil. The species nests on the ground and the colonies contain 70–96 workers. Ant activity is negatively correlated with temperature, and is more intense at dawn and dusk. Foragers leave the nest independently and search for food individually on the leaf litter, within ca 10 m around the nest. Workers are opportunistic feeders that collect seeds and fruits, and hunt for live prey as well as scavenge for dead animal matter. The dry weight of food items ranges from <10 mg (spiders, insect parts) to >400 mg (seeds, fruits). There is no nestmate recruitment during the search for or retrieval of food, irrespective of food type and size. Foragers have a high directional fidelity, and ants from neighbouring colonies may engage in ritualized territorial contests at the border of their foraging areas. The foraging ecology of D. gigantea is compared with other ponerine species living in tropical forests, as well as with other ant groups showing similar behavioural patterns.     

The parasitoid complex and parasitoid‐induced mortality of spiders (Araneae) in a Central European woodland

The parasitoid complex of spiders was studied in three different sites of a forest and, for comparison, in open habitats in north‐western Lower Saxony (Germany). Qualitative data and, for four spider species, detailed quantitative rearing data were obtained. At least 25 parasitoids of spiders were recorded (23 species of Hymenoptera and two species of Diptera). External parasitoids of spiders were rare in the woodlands; only up to 1% of the spiders collected by hand searching and sweep netting had ectoparasitoids. During the investigation 23 parasitoid species were reared from spider egg masses, 10 of them occurring in woodlands. Two species were secondary parasitoids. Several parasitoid–host relationships were recorded for the first time. Egg masses of Floronia bucculenta were parasitized up to 5% by two species of the genus Gelis. Up to 10% of the egg masses of Linyphia hortensis were parasitized by Aclastus species. Egg masses of the spider genus Ero were parasitized by three species, causing an overall mortality of 40%. For egg masses of Agroeca spp. parasitization at some locations was up to 60%. An overview of the Central European parasitoid complex of spiders is provided.     

Temporal variation and structure of macro-epifauna associated with macrophytes in the Bizerte lagoon (Tunisia,SW Mediterranean Sea)

The temporal variation in composition and abundance of the macro-epifauna associated with seaweeds (Ulva lactuca, Cladophora sp., Gracilariopsis longissima and Gracilaria bursa-pastoris) and seagrass (Cymodocea nodosa) was investigated at Menzel Jemil station in the Bizerte lagoon. Twelve replicate samples (25 x 25 cm frame) were collected monthly from October 2009 to September 2010. Sampling data yielded 21,575 invertebrate specimens from floating seaweeds and the seagrass, belonging to 40 taxa, of which 18 species were arthropods, 13 molluscs, three echinoderms, three fishes, two polychaetes and one cnidarian. Crustaceans were the most dominant and the most species-rich group and Idotea balthica basteri the most abundant species, accounting for 28.94% of the total abundance. Minimum (9.25 ± 5.56 species) and maximum (19.75 ± 3.2 species) values of mean species richness were observed in December and June, respectively. Species richness and density of macro-epifauna showed similar trends to plant biomass and the highest values of both indices coincided with periods of maximal plant biomass. Mean values of Shannon’s index H′ and evenness J′ were low, ranging from 0.34 ± 0.02 bit to 1.08 ± 0.06 bit, and from 0.23 ± 0.03 to 0.52 ± 0.07, respectively. The high dominance of herbivores and detritivores highlighted the substantial role played by macrophytes as food source for associated macro-epifauna species. Multivariate analyses also indicated significant seasonal differences for the macro-epifauna assemblage and revealed significant relationships with environmental variables. According to the canonical correspondence analysis, concentrations of phosphates and nitrites, and temperature were the variables that explained the variation of the macro-epifauna abundance in the Bizerte lagoon.     

Host ranges of parasitoids (Hymenoptera: Braconidae and Ichneumonidae) reared from Epermenia chaerophyllella (Goeze) (Lepidoptera: Epermeniidae) in Britain,with description of a new species of Triclistus (Ichneumonidae)

The complex of parasitoids attacking larval stages of Epermenia chaerophyllella in Britain is outlined, and the host range of each of the species recorded (three braconids and four ichneumonids) is discussed. ‘Ecological’ factors, such as the behavioural similarity of unrelated hosts during the vulnerable parts of their life histories, seem to have been important in the evolution of the host associations of several of these parasitoids, even though they are koinobionts. A new species, Triclistus epermeniae Shaw and Aeschlimann, is described.     

Spatial and temporal organization in three syntopic species of the Scinax ruber group (Anura: Hylidae) in the Atlantic rainforest,southeastern Brazil

Coexistence of anuran species might lead to acoustic interference among communications, especially where species are closely related. This problem might be minimized through resource partitioning. To test this idea, we analysed calling with respect to temporal and physical space usage in three syntopic, closely related species (Scinax cuspidatus, Scinax aff. hayii and Scinax aff. x-signatus) in a temporary pond in the Atlantic rainforest. The chorus attendance of each species resulted from a different combination of factors in the rainy season. Although there was some temporal overlap of daily activity among species, peak activity time differed, particularly between the two species whose calls were most similar. Although all three species tend to aggregate in open microhabitats, their coexistence is apparently facilitated by differential use of vertical strata and organization of calling sites near the sites of conspecifics. Together, these factors apparently reduce acoustic interference among heterospecific calls.     

Aquatic macroinvertebrate assemblages associated with root masses of water hyacinths,Eichhornia crassipes (Mart.) Solms-Laubach, 1883 (Commelinales: Pontederiaceae) in Taabo Lake,Ivory Coast

We examined aquatic macroinvertebrates associated with Eichhornia crassipes roots at five sampling sites in Taabo Lake. An average density of 1644 individuals (ind.)/m² was recorded. In total, 68 macroinvertebrate taxa belonging to 34 families and 14 orders were identified. Among these, Insecta was predominant (77.94%). The highest densities were recorded at Taabo cité during both rainy and dry seasons. Taxon diversity differences were not observed among all stations according to a Kruskal–Wallis test. High densities of predators were recorded. Next most prevalent in the trophic structure were detritivores. Indicator taxa analysis, using the Indval method, showed that stations upstream of the lake were characterized by eight taxa, while 11 appeared as indicators of the station near the dyke. Predators and herbivores dominated within those indicators. Sites near bays were distinguished by 18 indicator taxa with a predominance of predators and detritivores. Conductivity, NH₄ ⁺, temperature, PO₄ ^3?, turbidity and dissolved oxygen were parameters that strongly influenced the macroinvertebrate community.     

A new genus and new species (Orthoptera: Acrididae: Gomphocerinae) from south-east Xizang,China

In 2007, a 3-year survey was started in northeastern Italy to assess the influence of agricultural management on parasitoid composition and parasitism rates of parasitoids attacking larvae and pupae of Syrphidae (Diptera). Two types of management were considered – intensive (including wheat and maize monoculture with very low or null vegetation diversity) and extensive (with different types of habitats, characterized by a higher vegetation complexity). In habitats simplified by intensive agriculture, and particularly in maize fields, parasitism rates of syrphid larvae were higher than recorded in more diversified habitats. A substantial difference in the composition of the parasitoid complex was also found. In extensive and wheat sites, Diplazontinae (Braconidae), highly specialized to Syrphidae, were the dominant parasitoids, whereas in maize fields Pachyneuron (Pteromalidae) species, known as generalists, accounted for more than 80% of total parasitoids. In the habitats where Pachyneuron spp. were dominant, parasitism rates were very high. Conversely, in habitats where Diplazontinae were more abundant, the parasitism rates were very low. The higher rate of parasitism of syrphid larvae and pupae recorded in intensive monocultures could have a large impact on the development and control of aphid populations in such crops.     

The parasitoid complex attacking coexisting Spanish populations of Euphydryas aurinia and Euphydryas desfontainii (Lepidoptera: Nymphalidae,Melitaeini)

We report on a five‐year investigation of the complex of parasitoids associated with coexisting populations of Euphydryas aurinia and Euphydryas desfontainii at a Spanish site. A sample of over 7000 eggs, 1000 larvae and 200 pupae (the last of these in part having been experimentally placed) revealed the existence of no egg parasitoids, of three primary larval parasitoids and of five primary pupal parasitoids, plus 13 secondary and facultatively tertiary parasitoids associated with the cocoons of the main larval parasitoid, the specialist Cotesia sp. D. The most abundant secondary parasitoid, Neochrysocharis albiscapus, entirely escaped tertiary parasitism by being gregarious. The mortality induced by parasitoids on the butterfly populations, although heavy, was clearly partially minimized by secondary parasitoids acting on Cotesia sp. D. The striking coincidence of the parasitoid complexes attacking the two Euphydryas species suggests a good system for investigating apparent competition between hosts sharing common natural enemies.     

Observations on the nesting behaviour of seven species of Crabro (Hymenoptera,Sphecidae)

Summary

Data are presented on the nests and prey of seven species of Crabro from diverse localities in North America. In two instances (virgatus and largior) this is the first published report. Further information is provided for the following previously studied species: argusinus, advena, cribrellifer, latipes, and monticola. Behavioural differences among these species are not conspicuous. Most are rather general fly predators, but cribrellifer appears to show a strong preference for Asilidae. There are also differences in type of soil used for nesting and in antipredator behaviour such as approach flights and daily cycles of activity. Two species, largior and monticola, provision their nests early in the morning, before miltogrammine flies are active in numbers. All species probably make cells of two sizes, larger cells containing more prey and producing females, smaller cells males.     

Two new Encarsia species (Hymenoptera: Aphelinidae) reared from eggs of Cicadellidae (Hemiptera: Auchenorrhyncha) in Argentina: an unusual new host association

Males of two undescribed Encarsia species were reared from eggs of two cicadellid species during a study of egg parasitoids of corn leafhopper, Dalbulus maidis (DeLong and Wolcott) in northwestern Argentina. Samples were collected during the summer of 2004–2007 using sentinel eggs, and several males of a new species of Encarsia (Hymenoptera: Chalcidoidea: Aphelinidae) were obtained. A single male of a closely related Encarsia species, also previously undescribed, was reared from an egg of another cicadellid on maize, Plesiommata mollicella (Fowler). These are the first records of any Encarsia species reared from eggs of Cicadellidae. The two new species are described as Encarsia dalbulae Polaszek and Luft Albarracin sp. nov., and Encarsia mollicellae Polaszek and Luft Albarracin sp. nov.     

Rare fishes from the Clyde sea area

Summary

The swarming flights of 23 species of termite were observed at three localities within Brazil and data collected on the periodicity of swarms, the predators which attach the exposed termites and the defensive behaviour of the three castes of termites.

The principal predators on termites during swarming were ants at ground level and birds in the air. The defensive behaviour of workers and soldiers effectively protected the termite alates from terrestrial predators, but only the low level of light at dawn and dusk protected them from aerial predators.

Most of the termites released their alates at the beginning of the rainy season, either at dawn or at dusk and protected them from grounded predators with a ‘blanket’ cordon of workers and soldiers.

Three species of the subterranean, soldierless Anoplotermes constructed special launching towers for the release of alates and protected them from predation with these structures. Armitermes euamignathus and Cornitermes cumulans also built launching structures on their nests for alates, but showed the ‘blanket’ behaviour of most termitids in their defence.

The towers constructed by the three species of Anoplotermes indicated, by their distribution and number, the density and approximate size of the subterranean colonies which built them. A mean density of 240 nests ha^-1 and 258·24 termites m^-2 was estimated for Anoplotermes sp I.     

Plecoptera and Trichoptera species distribution related to environmental characteristics of the metal-polluted Arkansas River, Colorado

The Upper Arkansas catchment has been polluted with heavy metals from mining for almost 140 yr. Adult Plecoptera and Trichoptera species distributions were recorded from 22 stations along 259 km of main river during 1984-85 so that these could be related to metal deposition and other environmental characteristics. Chemically or physically perturbed sites had poor species richness compared with adjacent sites. There was no sequential downstream increase in species numbers. Filter-feeders proportionally increased downstream as predators declined; these proportions were reset at a high-energy site before the trend resumed. Using canonical correspondence analysis, we found that species composition was most strongly related to changes in distance/altitude and to temperature, particularly after regulatory flows entered the river. The proportion of biological variation explained by river measurements indicated that collected adults were largely derived from the main Arkansas River. Species tolerant of high sedimentary metal concentrations were identified while some other species appeared to be sensitive. The study provides a disturbed-state reference for monitoring effects of remedial actions begun in 1991, and for comparisons with other Colorado rivers.