Showing papers in "Ecological Entomology in 1978"
TL;DR: The time‐course of anthesis of Echium vulgare is described and the chiral stationary phase experiment shows clear signs of chiral “crushing” as well as “spatially aggregating” during the anthesis phase.
Abstract: . 1. The time-course of anthesis of Echium vulgare is described.
2. Diel changes in the sugar concentration of the nectar, the quantity of nectar and the quantity of sugar per flower are illustrated for E.vulgare and for Sinapis alba.
3. These changes are interpreted in terms of (a) the periodicity of secretion and (b) the influence of microclimate and insect visits on post-secretory changes in the composition and volume of nectar.
4. There was hour-to-hour and day-to-day variation in the species composition and the proportion of workers taking nectar rather than nectar plus pollen among the social bees visiting E.vulgare.
5. Honeybee visits to E.vulgare were more numerous in humid weather, when there was enough nectar per flower for their relatively short tongues to reach, and in an area where the corollas grew shorter than they did elsewhere.
6. The significance of changes in the caloric content, volume, concentration, viscosity and sugar composition is discussed from the points of view of insects and ecologists.
162 citations
TL;DR: The data for dispersal of Drosophila pseudoobscura of Dobzhansky & Wright (1943) were re‐examined and an improved description found for them.
Abstract: . 1. The data for dispersal of Drosophila pseudoobscura of Dobzhansky & Wright (1943) were re-examined and an improved description found for them.
2. The equation that best described the dispersal of D.pseudoobscura was found not to be applicable to the dispersal of five other insect species.
3. Eight equations describing the density-distance relation were fitted to the dispersal data of eight insect species. No equation fitted all the data adequately.
4. A general expression was deduced from comparison of the eight equations, and found to fit all species better than any of the special cases.
135 citations
TL;DR: Calculations have been made of the coefficients of selection which would be required to produce rates of evolution in wild populations of Anopheles culicifacies and An.stephensi to determine whether the resistances might be effectively dominant, recessive or intermediate.
Abstract: . 1. From published data on the rate of build-up of insecticide resistance in wild populations of Anopheles culicifacies and An.stephensi, calculations have been made of the coefficients of selection which would be required to produce these rates of evolution. It is assumed in turn that the resistances might be effectively dominant, recessive or intermediate.
2. The results in the case of DDT resistance in An.culicifacies indicated that the fitness of resistant individuals was 1.28–1.51 × that of susceptibles.
3. Published data have also been examined with reference to the reversions towards susceptibility which occurred when spraying has been withdrawn. The coefficients of selection against resistance, which would be required to produce the observed rates of reversion, have been calculated. In the case of An.culicifacies and DDT these coefficients were found to be inversely related to the initial frequency of the susceptibility gene.
4. The coefficients of selection have been used to assess the feasibility of inhibiting the evolution of resistance by spraying different insecticides in the alternate sectors of a grid pattern and/or periodically releasing susceptible males. If the proportion of migrants from sector to sector were 15–30%, a “grid” system would considerably reduce the rate of evolution of resistance, but to prevent resistance from ultimately building up to high levels periodic releases would also be required. These releases need not be frequent (approximately during one month each year) if resistance is effectively recessive in the field.
124 citations
TL;DR: Histological sections of tree roots on which periodical cicada nymphs of both the 17‐year and the 13‐year race arid various instars had fed showed that salivary sheaths made by the nymphS ended in xylem vessels.
Abstract: . 1. Histological sections of tree roots on which periodical cicada nymphs of both the 17-year and the 13-year race arid various instars had fed showed that salivary sheaths made by the nymphs ended in xylem vessels.
2. Because no salivary sheaths were found in phloem cells, this observation indicates that cicada nymphs are xylem feeders throughout their developmental period.
3. The habit of feeding on xylem fluid, which is extremely dilute, may explain why periodical cicada nymphs require so many years (13 or 17) to mature. It may also explain why they excrete amino acids rather than sugars, as phloem feeders do.
113 citations
TL;DR: Subterranean aphids in old pasture were found to show extremely clumped distributions with about 3000 aphids (omitting first instars) per ant nest throughout the year.
Abstract: . 1. Subterranean aphids in old pasture were found to show extremely clumped distributions with about 3000 aphids (omitting first instars) per ant nest throughout the year.
2. They were generally distributed in and away from the nest mounds, but within the ant's foraging territories.
3. At summer temperatures, more than 3000 first instars are lost from the aphid population per ant nest per day and it is concluded that these are eaten by the ants in addition to some older aphids and the honeydew produced.
4. The aphids may therefore provide enough food to maintain the ants with very little extra needed in the form of other prey.
96 citations
TL;DR: The population and physiological measurements were made on monarch butterflies in three overwintering colonies along the California coast during the 1975–76 season to establish a baseline for future studies.
Abstract: . 1. Population and physiological measurements were made on monarch butterflies in three overwintering colonies along the California coast during the 1975–76 season.
2. Mark, release and recapture studies indicated that two northern colonies (Muir Beach and Santa Cruz) stabilized at maxima of about 40000 and 95 000 individuals with little movement in or out of colonies, whereas the southern one at Santa Barbara appeared dynamic with a maximum of about 45 000.
3. Initially low, sexual activity builds to a massive mating ceremony in February, followed by rapid colony dispersal. The butterflies deteriorate gradually during the overwintering period, but males do so to a greater extent because of their involvement in frenzied courting flights.
4. Changes in several parameters at the Muir Beach colony were measured between 1 November and 2 February. Right forewing length did not change with time, indicating no differential mortality with respect to size. However, both sexes lost about 25% of their total dry weight, and 49–60% of their lipid contents. Minimum fat levels were about 20 mg and some butterflies were as lean on arrival as were the most depleted overwintering survivors.
5. The importance of nectaring in restoring lipid reserves is potentially great but remains uninvestigated. The hypothesis is put forward that the distance spring migrants are capable of flying is dependent largely upon their lipid reserves following the overwintering period. This and the intracolony mass-mating ceremony are seen as randomizing factors which prevent geographic differentiation and allow the maintenance of the generalized, nature of the migration, which in turn enables the monarch to exploit the vast milkweed flora across the North American continent.
6. Cardenolides also diminished during the wintering, but to a substantially lesser extent than the lipids. There was no evidence for a change in the proportion of cardenolide-positive butterflies, suggesting no differential elimination by predation of the poison-free palatable individuals. This is the first field evidence in support of the theory of automimicry.
7. The overwintering behaviour of the monarch butterfly is seen as an integrative force in optimizing foodplant exploitation, reproduction, anti-predator, and migration strategies.
80 citations
TL;DR: A 24 h time‐sorting pitfall trap was used to collect Carabidae in a field in north‐east England in 1974, 1976 and 1977 to study the behaviour of these birds of prey.
Abstract: . 1. A 24 h time-sorting pitfall trap was used to collect Carabidae in a field in north-east England in 1974, 1976 and 1977.
2. Harpalus rufipes comprised 62% of the 5288 adult Carabidae caught. It was nocturnal, with an activity peak after midnight. The male activity pattern lagged behind that of females by about 1 h. The activity peak shifted to earlier in the night during September.
3. Activity curves are given for eighteen other common species. Large species were all nocturnal, but a third of the smaller species were active in the day. The numbers caught of twenty-eight less common species are tabulated and show the same trend. Overall, nearly 60% of all species caught were nocturnal and 20% diurnal; the remainder did not show a distinct pattern of day or night activity.
4. A total of eighty-two larvae of H.rufipes, Nebria brevicollis and Notiophilus biguttatus were caught, and showed similar activity patterns to those of the respective adult beetles.
78 citations
TL;DR: Examination of the ovaries of female olive flies from wild populations on Corfu during the summer months of 1975 indicated that all were non‐gravid for a period of several weeks during June and July and the terminal follicles were resorbed.
Abstract: . 1. Examination of the ovaries of female olive flies (Dacus oleae) from wild populations on Corfu during the summer months of 1975 indicated that all were non-gravid for a period of several weeks during June and July and the terminal follicles were resorbed.
2. Experiments in outdoor cages indicated that olive fruits could stimulate ovarian development during the summer months.
3. Experiments in constant temperature cabinets indicated that high temperatures (i. e. 26–29°C) in conjunction with a low humidity (45 ± 5°%) inhibited ovarian maturation.
4. Whereas the presence of olive fruits offset the effects of temperature and humidity on ovarian development at 26°C in all flies, at 29°C very few were able to mature their ovaries.
5. It is suggested that it is the interaction of temperature, humidity and access to fruit which determine when ovarian maturation ceases and recommences during the summer months.
78 citations
TL;DR: Two usual definitions of host discrimination are presented and it is found that the ability of a parasite to distinguish unparasitized from parasitized hosts and to lay eggs in the former is not useful and even confusing.
Abstract: Two usual definitions of host discrimination are presented. The first is 'the ability of a parasite to distinguish unparasitized from parasitized hosts and to lay eggs in the former'. This definition is not'useful and even confusing since it does not include the ability of a parasite to distinguish hosts containing different numbers of parasite eggs and to lay preferably only in those with the lowest numbers. 2. The second definition is 'the ability of a parasite to distribute its eggs in a non-random, regular way among its hosts'. It is argued that most field data are insufficient to permit any conclusions about host discriminative ability on the basis of this definition. An example is given of an apparent random distribution by parasites that are perfectly able to discriminate. 3. Arguments are given for studying the behaviour of the parasite in order to answer the question of host discrimination. Five examples of parasites are presented that would erroneously have been classified as non-discriminators on the basis of the first definition, since they all superparasitize. 4. It is suggested that the meaning of the term 'host discrimination' be extended to include the ability of a parasite to distinguish hosts with different numbers of eggs.
73 citations
TL;DR: The various groups of arthropods associated with rodent carrion during decay in temperate woodland and grassland habitats are described in each of four seasons.
Abstract: . 1. The various groups of arthropods associated with rodent carrion during decay in temperate woodland and grassland habitats are described in each of four seasons.
2. A distinction is drawn between those occurring by chance and those positively associated with the carrion.
3. The role of these last in actually assisting the decay of the carcasses with which they are found is discussed. Despite the abundance and diversity of carrion-frequenting species, few are involved to any significant extent in the release of carrion materials during decomposition.
72 citations
TL;DR: Results suggest that laboratory ants preferred eating whole ant fungus staphylae to hyphae, and did not feed on other fungi, while other homogenized fungi were not drunk extensively.
Abstract: . 1. Laboratory ants preferred eating whole ant fungus staphylae to hyphae, and did not feed on other fungi. Homogenized ant fungus staphylae and hyphae were equally acceptable liquid food but other homogenized fungi were not drunk extensively.
2. Various arthropod fungjvores preferred to feed on ant fungus rather than any other fungus tested. Some preferred hyphae to staphylae, some vice versa and others had no preference.
3. The ants attacked animals on the nest and reduced the numbers of fungivores on the fungus garden.
4. The ant fungus grew best at 24.5°C and hardly at all at 10°C or 37°C.
5. The ants did not necessarily choose material which supported the best fungus growth in sterile culture and readily accepted substrates on which the fungus did not grow at all. No learning behaviour was noted.
6. The ant X fungus symbiosis is discussed as an example of co-evolution, a product of an evolutionary feedback. The ant is supplied with a highly nutritious, readily acceptable food source in return for complex fungus-culture behaviour, providing protection from fungivores and competition from other saprophytic fungi.
TL;DR: This work has explored the question of whether breadth of diet in moths is associated with adaptations other than host selection behaviour, with particular reference to body size, and found no support for this conclusion.
Abstract: . 1. We have explored the question of whether breadth of diet in moths is associated with adaptations other than host selection behaviour, with particular reference to body size.
2. Generalist species in Britain and New York are larger than specialist species.
3. This relationship is probably not due to latitudinal clines, nor to higher fecundity in generalist species.
4. We suggest that the large bodies of generalists buffer them against environmentally-induced physiological stress.
TL;DR: In Seychelles, A. longipes nests on the ground and in trees, underground nests do not occur, possibly because soils are too hard or unstable.
Abstract: . 1. In Seychelles, A. longipes nests on the ground and in trees, underground nests do not occur, possibly because soils are too hard or unstable.
2. Nest density approached 700 ha-1 in some areas and nests contained, on average, about 4000 ants. The total population (including foragers) in heavily infested areas may exceed 10 millions ha-1.
3. On average, each nest contained about forty queens and fifty males, although only 50% of nests contained males. A few nests contained up to 300 queens, 1000 males, 36 000 workers and 23 000 brood.
4. Production of sexual adults and brood was related to the wet season, most being produced shortly before or after the heavy rains from November to March.
5. Natural spread is probably by budding of colonies which, during an expansive period, may advance 1 m day-1.
6. Food collected by the colony included sugary substances from fruits, honey-dew-producing insects and plant exudates, and proteinaceous material, mainly in the form of insect prey and carcases. A forager collected, on average, 1.2 mg of liquid or 2.8 mg of solid material on each foraging trip.
7. Foraging occurred at fluctuating intensities throughout the day and night, but was limited by heavy rain, strong winds and substrate temperatures above 30°C. Maximum activity occurred at ground temperatures of 25–30°C and ceased about 44°C.
8. Availability of food and nest sites proably have the greatest influence on population size.
TL;DR: The role of the host plant, Acacia karroo, in the population dynamics of the indigenous non‐pest psyllid, Acizzia russellae, was investigated.
Abstract: . 1. The role of the host plant, Acacia karroo, in the population dynamics of the indigenous non-pest psyllid, Acizzia russellae, was investigated.
2. Population levels of A.russellae in early summer were almost 10 times greater on the regenerative foliage of pruned trees (cut back in spring) than on normal trees. During late summer and winter, populations declined far more slowly on pruned trees, so that very much higher numbers of psyllids were maintained on these trees through to the next spring. This finding, and others, suggest that natural enemies and climate are not major determinants in the population dynamics of this insect under normal conditions in the field.
3. Laboratory measurements of several chemical and physical characteristics of the foliage of pruned and normal trees did not reveal any differences which would account for the observed effects.
4. Measurements of organic nitrogen concentrations in the leaves of normal A. karroo trees in the field showed significant correlations between psyllid numbers and leaf nitrogen, but only during summer in November and January.
5. Psyllid performance in the laboratory (duration of life cycle, egg production, and dry weight of emergent females) was significantly better for psyllids reared on plants containing high amino nitrogen.
6. It is suggested that the availability of quantities of suitably high quality nutrients in the leaves of pruned A. karroo trees explains the “epidemic” population levels achieved by the psyllid on pruned plants. It seems that characteristics of the host plant impose the major limitation on psyllid population growth, which may explain the permanent low endemic population levels of this insect in the field.
TL;DR: A survey of Culicoides breeding places was made around Salisbury and found that out of forty species caught in light traps, only nineteen were reared from breeding places.
Abstract: . 1. A survey of Culicoides breeding places was made around Salisbury. Out of forty species caught in light traps, only nineteen were reared from breeding places.
2. The seven most abundant species with their characteristic sites were C.pycnostictw in mud around water bodies, especially dams; C.nivosus very prevalent around puddles rich in organic matter:C. distinctipennis along drainage canals intermediate in organic matter; C.gulbenkiani in cow dung especially on damp soil; Caccraensis gp. only in rot holes and tree forks; Cschultzei gp. along streams and drainage canals in mud rather poor in organic matter; C.tropi-calis in drainage canals very low in organic matter; C.imicola possibly breeds widely dispersed mainly in a rich mixture of organic matter and damp soil, with cow pats and edges of water bodies being marginal.
3. The prevalent species are believed to breed all year round. Preponderance of females in the breeding places was found in C.pycnostictus, C.nivosus and C.accraensis gp. while the reverse was true in C.distinctipennis and C.gulbenkiani. The preponderance of males as indication of proximity to breeding sites is thus probably questionable.
TL;DR: The causes and incidence of mortality in populations of the yew gall midge Taxomyia taxi at Kingley Vale, West Sussex, are described in relation to the various life cycles of the midge.
Abstract: . 1. The causes and incidence of mortality in populations of the yew gall midge Taxomyia taxi at Kingley Vale, West Sussex, are described in relation to the various life cycles of the midge.
2. Life table analysis of populations studied for 10 years indicates that the key factor in mortality is failure to achieve maximum fecundity, although in 1-year life cycles parasitism by Mesopolobus diffinis is equally important. Densities and mortality vary considerably between different life cycles, and no regulation has been firmly established.
3. Interactions between the host populations and their parasites are complex and as yet not fully analysable, but the pattern of parasitism seen may explain some of the complex life history pattern of the host. The existence of long-term cycles of host and parasite densities are predicted.
TL;DR: Insect flotsam was obtained from marine pleuston samples from the English Channel, off the Oregon coast (U. S. A.), and in the Gulf of California (Mexico).
Abstract: . 1. Insect flotsam was obtained from marine pleuston samples from the English Channel (U. K.), off the Oregon coast (U. S. A.), and in the Gulf of California (Mexico).
2. Only ten orders of insects were represented, Coleoptera, Diptera and Homoptera being the most abundant.
3. Staphylinidae and Chironomidae were the most abundantly represented families taken from the English Channel, comprising 43% and 18% respectively of total insects sampled.
4. Aphididae comprised 39% of the Oregon Coast samples.
5. Aphididae (42%) and Cicadellidae (17%) accounted for 59% of the insects in the Gulf of California.
6. Fish may feed on surface insects at night and this may account for the lower numbers found in early morning samples.
TL;DR: This article found that large Bombus vagans workers concentrated their foraging upon deeper florets of cow vetch (Vicia cracca) more than did smaller workers and that small B.vagans workers became secondary robbers at holes made in vetch corollas.
Abstract: . 1. Large Bombus vagans workers concentrated their foraging upon deeper florets of cow vetch (Vicia cracca) more than did smaller workers. Large and small workers did not differ significantly in their foraging rates, which were measured in several ways.
2. The average depth of vetch florets varied between sites on the study area, but significant differences did not occur on a single inflorescence. The foraging differences of large and small bees probably result from a fine partitioning of the microhabitat.
3. When the nectar-robbing B.terricola was present, many B.vagans workers became secondary robbers at holes made in vetch corollas. Small B.vagans workers robbed significantly more frequently than did large workers.
TL;DR: The position and zonation of mines and galls along beech leaves were recorded and analysed by means of an R X C test of independence using the G‐test; in a few cases analysis of variance was applied.
Abstract: . 1. The position and zonation of mines and galls along beech leaves were recorded and analysed by means of an R X C test of independence using the G-test; in a few cases analysis of variance was applied.
2. Ten arthropod species, of which a few were congeneric, were studied. All species were recorded from all leaf sections; however, in all species except one, significant preferences for certain zones were demonstrated. High frequencies of leaf mines and galls were recorded from the middle and basal leaf sections. Apparently, the leaf apex is an unimportant microhabitat for stationary beech phyllophages, except the eriophyid Aceric stenaspis stenaspis and final leaf mining stages of the beech weevil Rhynchaenus fagi; intra-leaf differences are discussed in relation to leaf grazing by mobile, chewing phyllophagous insects.
3. The position of some abundant phyllophages in space and time is discussed. In old beech stands feeding activity is largely concentrated in the low canopy. Presumably, differences in feeding technique and position of feeding tracks of beech phyllophages on the leaf contribute to food resource partition in this canopy layer. In three congeneric eriophyid species niche diversification occurred. Further, in two cecidomyiid species phenologjcal differentiation may contribute to subdivision of food resources.
TL;DR: The distribution of adult males, nymphs and larvae of the reptile tick Aponoma hydrosauri on their host, Trachydosaurus rugosus, in a study area near Tickera, South Australia, did not follow the Poisson distribution predicted if hosts were infested at random.
Abstract: . 1. The distribution of adult males, nymphs and larvae of the reptile tick Aponoma hydrosauri on their host, Trachydosaurus rugosus, in a study area near Tickera, South Australia, did not follow the Poisson distribution predicted if hosts were infested at random.
2. The non-random distribution of males can be accounted for by geographical heterogeneity in distribution. Adult females also showed geographical heterogeneity in their distribution pattern, but infested their hosts at random over all.
3. Larvae and nymphs show distribution patterns which change both with the time and the locality. However, when these biases are removed the distribution of larvae and nymphs on their hosts is still non-random.
4. Larger lizards tend to have larger numbers of ticks, but this cannot alone account for the clumped distribution.
5. A model is proposed relating the tick distribution pattern to the particular problems of a resource which is hard to find, but plentiful once found.
TL;DR: The spatial distribution of both adult apterous and nymphal M.persicae was related to the “age” of the leaf.
Abstract: . 1. The spatial distribution of both adult apterous and nymphal M.persicae was related to the “age” of the leaf.
2. This distribution was bimodal and was maintained even on rapidly “ageing” leaves by frequent emigration.
3. The spatial distribution was also found to change between regions of a leaf, the densest populations occurring at the base of all leaves, but with the populations most evenly distributed on the young and old leaves.
4. The spatial distribution also changed during the nymphal period, the youngest nymphs being found predominantly on the lamina, the fourth instar and adults on the largest available veins.
5. On rapidly growing plants, individual M.persicae may move to a new feeding site as frequently as every 24–48 h.
6. Some of the causes and consequences of this frequent dispersal are discussed.
TL;DR: The adult biology of the solitary mud‐wasp Sceliphron assimile Dahlbom was studied in Jamaica and it was found that males are more sexually promiscuous than females, while females are more secretive and territorial.
Abstract: . 1. The adult biology of the solitary mud-wasp Sceliphron assimile Dahlbom was studied in Jamaica.
2. Adults were active from sunrise until they finally settled in roosting groups a little before sunset. Nesting took place during an 8.5 h period commencing about 3 h after sunrise but individuals rarely spent > 4 h nesting per day, the remainder being spent in resting and feeding.
3. Males sought females in all places in the habitat.
4. The number of cells per nest was positively correlated to high cell density per unit area but negatively correlated to illuminance.
5. The number of pellets used to build a cell, but not cell length, was negatively correlated to the body length of the builder. There is evidence that females that build multiple nests locate them within a few metres of each other.
6. Incompletely stored cells were closed with an externally concave lamella of mud at the onset of rain or at 16.00—17.00 hours E.S.T. and never reopened the same day.
7. Like other species of Sceliphron studied in this respect S. assimile collected spiders belonging to the Argiopidae (particularly), and also mainly to the Thomisidae, Salticidae and Oxyopidae.
8. The consequences of the nest architecture on mortality and the method of building on distribution are discussed.
9. Protarrhenotoky and proterandry occur and probably influence the sex ratio through differential mortality and fecundity. A suggested interaction between the flight motor and the ovaries could regulate egg production.
TL;DR: In coastal Kenyan forests the most productive breeding habitats of Eretmapodites subsimplicipes are rain‐filled fruits of the Apocynaceae and Loganiaceae cast off by monkeys.
Abstract: . 1. In coastal Kenyan forests the most productive breeding habitats of Eretmapodites subsimplicipes are rain-filled fruits of the Apocynaceae and Loganiaceae cast off by monkeys.
2. Water incubated in fruit husks stimulates females to oviposit, but a sympatic congener Eretmapodites quinquevittatus, never found in fruits, prefers tap water.
3. Thus, chemical discrimination of oviposition site may promote the micro-habitat separations observed in nature.
TL;DR: In laboratory experiments, R.fagi made feeding holes in eighteen tree and shrub species, including beech, from seven plant families but few plants other than beech were eaten to any extent.
Abstract: . 1. In laboratory experiments, R.fagi made feeding holes in eighteen tree and shrub species, including beech, from seven plant families but few plants other than beech were eaten to any extent.
2. Overwintered adult weevils preferred beech to all these eighteen plants in spring.
3. Hawthorn and raspberry were the most acceptable plants if beech was not available at this time.
4. Field collected weevils from hawthorn had partly developed oocytes in early April, prior to beech bud burst.
5. New generation weevils sought alternative food sources in late June and July; raspberry was preferred to the youngest available beech leaves at this time.
TL;DR: This data indicates that landlocked intertidal pools (potholes) are one of the common aquatic habitats associated with eastern North American salt marshes and should be considered a priority for future research.
Abstract: . 1. Landlocked intertidal pools (potholes) are one of the common aquatic habitats associated with eastern North American salt marshes.
2. Twenty species of insects, of which only eight were common, occurred in the pothole habitat. The harshness of the physical environment incurred in the pothole habitat is largely responsible for this depauperate insect community.
3. Spatial variation in the diversity of the insect community is best explained by differential densities of predaceous fish.
4. Seasonal changes in insect community diversity are attributable to fluctuations in water temperature and accompanying levels of dissolved oxygen.
TL;DR: Trapping experiments and observations of sexual behaviour were made on Cephalcia lariciphila in infested larch forests in Hereford and Worcester and Mid‐Glamorgan in early May 1977.
Abstract: . 1. Trapping experiments and observations of sexual behaviour were made on Cephalcia lariciphila in infested larch forests in Hereford and Worcester and Mid-Glamorgan in early May 1977.
2. The results indicated that virgin females and dichloromethane extract of crushed virgin females were highly attractive to males.
3. On 17 May males responded to females throughout the warmest part of the day. First response occurred before 09.00 hours, the last after 17.00 hours and peak activity was from 11.00 to 14.00 hours.
4. Mated females became unattractive to males within 10 min after mating. When mated females or males were paired with virgin females there was no evidence of an anti-attractive pheromone or pheromone mask.
5. A few males dispersed out of larch into adjacent spruce forests and were captured in virgin female-baited traps up to 135 m distant from infested larch. Virgin female-baited traps at 0–0.5 m from the ground captured over seven times the number of males as traps at 1, 2 or 4 m, supporting visual observations that the preferred flight level for males is very near the ground.
6. Horizontal board traps with an acetate surface coated with ‘Stikem Special’ were superior to Pherocon IC, vertical board and gypsy moth traps in that order.
7. The observations and results suggest that the best applied uses of C. lariciphila pheromone would be in survey and detection, and male disruption techniques.
TL;DR: The common cassidid beetle, Stolas sp.
Abstract: . 1. The common cassidid beetle, Stolas sp., feeds as both larva and adult on the leaves of the vine, Ipomoea asarifolia, a wild relative of the sweet potato.
2. In the region around Manaus (Amazonas State, Brazil) an average of 86% of the egg clutches were completely parasitized by the eulophid, Emersonella niveipes.
3. The wasp is phoretic on female beetles. In comparison with field beetles that lacked phoretic wasps, beetles associated with wasps produced eggs sooner, laid more egg clutches, and had a shorter laboratory life expectancy.
4. Host discrimination by the wasp is probably an active process rather than a passive association with randomly encountered beetles.
5. Emersonella niveipes also attacks Chelymorpha cassidea, a pest of sweet potato. Adults of Stolas sp. do not feed on sweet potato foliage nor occur in sweet potato fields, so they could provide a useful innocuous alternate host for Emersonella niveipes.
6. As some species in the Convovulaceae are important weeds in field crops, foliage-feeding cassidid beetles may play a useful role in weed suppression. Any biological control programme for the suppression of sweet potato pests may favour the spread of those noxious weeds that share the herbivore fauna of sweet potatoes.
TL;DR: Repairs were provoked by contact with the defect, not by changes in humidity, and sliding and somersaulting movements allowed repair of different parts of a defect.
Abstract: . 1. G. spiniger larvae repaired openings in their cells by excavating dung from the brood-mass and placing it in the edge of the hole. Thrusting with the head sealed small holes but pushed dung away from larger defects. Sliding and somersaulting movements allowed repair of different parts of a defect. Repair was provoked by contact with the defect, not by changes in humidity.
2. Dung excavated at the anterior end of the cell was transferred by somersaulting, and thrust into the posterior end to seal off foreign bodies. Burrowing by the larvae depended on similar behaviour which moved the whole cell within the brood-mass.
3. Larvae were sensitive to surface contact, making a coordinated attack on a source of stimulation. They also moved towards dung and wet soil.
4. Fluid regurgitated by disturbed larvae killed blowfly larvae when injected, and repelled earthworms.
5. To construct a pupal cell, excavated material was transferred by somersaulting and used to build a transverse partition without the usual vigorous thrusting movements. The ability to re-initiate pupal cell formation was retained for about 4 days.
6. Larvae enclosed in artificial brood-balls enlarged defects while attempting to repair them, but larvae just prior to pupation taken from recently made pupal cells could repair such defects.
7. Aphodius fossor larvae rarely attempted to repair openings in their cells and usually escaped by burrowing (as above), but opening a recent pupal cell always provoked repair.
8. Repair by G. spiniger larvae is closely related to other larval activities but lacks several features that are important for repair by species developing in freestanding brood-balls.
TL;DR: The population of the lycosid Trochosa terricola Thorell was sampled from April 1973 to August 1975 at Weeting Heath NNR, a Breckland grass heath.
Abstract: . 1. The population of the lycosid Trochosa terricola Thorell was sampled from April 1973 to August 1975 at Weeting Heath NNR, a Breckland grass heath.
2. Four sampling methods were compared for efficiency. Hand searching gave density estimates between 38.3 and 70.1% of heat extraction.
3. The temperature range in the sward at +1 cm was –5°C to 39°C with January and July means of 3.2°C and 17.4°C.
4. Eight male and nine female instars were determined and the life cycle extended over 2 or 3 years.
5. Adults were nocturnal but the juveniles diurnal. An annual diplochrone activity pattern was observed for adult males.
6. The horizontal distribution within the sward was aggregated, the structure and microhabitat being important determining factors. The population density was greater in moist, young Festuca spp. tussocks. An equation relating population density to habitat characteristics was derived.
7. The overall population density ranged from 14.0 m-2 to 76.0 m-2 and was maximal in autumn after breeding. The population biomass was greatest during autumn (291.2 mg d.wt m-2).
8. Mean number of juveniles emerging from an egg sac was 77.3 (first sac) and 38.0 (second sac). The natality in 1973 was 66.8 individuals m-2.
9. The survivorship curve until maturity varied between types I and III in different years.
10. The population dynamics were compared and are discussed in the light of other data. The variable population characteristics suggested that Den Boer's “spreading of risk” theory applied to the T.terricola population.
TL;DR: A study was made of the oviposition sites of five leafhopper species Diplocolenus abdominalis, Recilia coronifera, Errastunus ocellaris, Elymana sulphurella and Dicranotropic hamata on the grasses Holcus mollis and H.lanatus.
Abstract: . 1. A study was made of the oviposition sites of five leafhopper species Diplocolenus abdominalis, Recilia coronifera, Errastunus ocellaris, Elymana sulphurella (Cicadellidae) and Dicranotropic hamata (Delphacidae) on the grasses Holcus mollis and H.lanatus.
2. Experiments were made in the laboratory, each insect species being provided simultaneously with a complete plant of both Holcus species.
3. Distribution of eggs within the leaf sheath and leaf blade, and their height above ground-level, were recorded.
4. The presence and size of egg groups were noted, as well as the angle of eggs to the longitudinal axis of the leaf.
5. On the basis of comparison of the vertical distribution of the eggs with availability of plant tissues, the five species can be divided into three groups: (a) D.abdominalis and R.coronifera, (b) D.hamata and E.ocellaris, (c) E.sulphurella. Species within a group, i.e. with similar distributions of eggs, have other features separating their oviposition sites.