Assessment of the range of attraction of pheromone traps to Agriotes lineatus and Agriotes obscurus

• 1 The range of attraction of YATLOR pheromone traps was studied to gain information on the number of traps needed for mass trapping of males of two Agriotes species.
• 2 Male click beetles of the species Agriotes lineatus (L.) and Agriotes obscurus (L.) (25–30 individuals per release point) were marked and released at a distance of 2, 5, 10, 15, 20 and 60 m from a pheromone trap both along and opposite to the known prevailing wind direction. Traps were regularly inspected over approximately 1 month. The percentage of recaptured beetles was calculated and analyzed using analysis of variance. Maximum sampling ranges and effective sampling areas were calculated.
• 3 Averaged over all five trials and distances, approximately 40% of the released beetles (A. lineatus and A. obscurus) were recaptured. The percentage recapture of male adults was significantly affected by release distance, whereas no differences were found for species and release direction.
• 4 Males were recaptured from all release points and the percentage recapture decreased (in part significantly) with increasing distance from 76% (2 m) to 35% (15 m) and 9% (60 m), respectively. Most of the beetles were recaptured within the first 3 days after release, independent of the distance, except 60 m. The effective sampling area for A. lineatus was 1089 m² after 12 days and increased to 1735 m² after 30 days. Corresponding values for A. obscurus were considerably higher: 1518 m² for 12 days and 2633 m² for 30 days.
• 5 We conclude that the range of attraction of the pheromone traps for A. lineatus and A. obscurus is comparatively low, providing high percentage recapture only for release distances up to 10 m. Accordingly, any approach targeted on preventing mating by male mass trapping would require a dense network of pheromone traps.

     

Population dynamics ofLuehdorfia japonica Leech (Lepidoptera: Papilionidae)

1. An adult population of a papilionid butterfly, Luehdorfia japonicaLeech , was studied by marking, release and recapture procedures in a hilly region in the suburbs of Kanazawa City, Japan.
2. Age of butterflies was estimated from the wing wear conditions, rated as winage categories 0 to 6.
3. Jolly (1965) andSeber's (1973) method was applied to the marking-recapture results for estimating the population parameters (sampling ratio, population size and survival rate).
4. Sampling ratio of males was consistently higher (around 50%) than that of females.
5. Newly emerged females were especially inactive, so that few of them were captured. From day 6.5 to day 10.0 they began to oviposit and became more active and more catchable.
6. An approximate sex ratio of 1∶1 was confirmed from the specimens collected in the field and by rearing experiments.
7. Daily survival rate was about 0.75–0.80 and mean longevity was about 4 days for both sexes. The maximum longevity observed was 17 days, for males and 21 days for females.
8. Dispersal by both sexes of the butterfly was more than 1 km.

     

Migration potential of the banana weevil Cosmopolites sordidus

• 1 The banana weevil Cosmopolites sordidus Germar (Coleoptera: Curculionidae) is a major pest in banana (Musa spp.) growing areas. The weevil is known to be relatively sedentary and closely associated with its host plant but little is known about the species' ability to migrate between banana fields and in nonhost habitats.
• 2 Mark–recapture experiments were conducted to assess the weevils' migration potential, possible differences between the sexes, and the relative attractiveness of pseudostem and pheromone baits.
• 3 One thousand two hundred marked weevils were released in the nonhost habitat at five distances (5, 10, 20, 40 and 70 m) from fresh pseudostem, and from pitfall traps baited with 45 mg of sordidin.
• 4 Two hundred males and 200 females were marked and released at five distances (5, 10, 20, 40 and 70 m) from the pheromone traps.
• 5 Distance and distance/bait interactions had a significant effect on recaptured weevils (binary logistic regression). The two baits were almost equally attractive to weevils in the range 0–10 m, whereas the pheromone was more attractive in the range 10–100 m.
• 6 Distance, bait and distance/bait interactions had a significant effect on the time elapsed from release to recapture (regression with life data) but the pattern observed was not consistent.
• 7 There was no significant difference between males and females with respect to distance or time elapsed from release to recapture.
• 8 The results obtained in the present study show that the migration potential of the banana weevil is greater than previously reported. This should be taken into account when new banana fields are established with clean planting material.

     

Ranging behaviour of a large freshwater invertebrate, the white-clawed crayfish Austropotamobius pallipes

• 1 Radio‐telemetry and mark‐recapture methods were used to study the summer movements of adult and juvenile white‐clawed crayfish, Austropotamobius pallipes from a wild population in a small braided stream, Dalton Beck, North Yorkshire, U.K. Radio‐transmitters were attached to the chelae of 18 large (> 35 mm carapace length) crayfish and individuals were subsequently located to within 0.15 m. Additionally a total of 888 crayfish were marked with carapace brands, and 83 were recaptured.
• 2 Radio‐tracked crayfish exhibited significantly greater local activity at dusk (21.00–00.00) than at dawn (03.00–06.00), or during morning (09.00–12.00) and afternoon (15.00–18.00) monitoring periods.
• 3 The greatest movements of radio‐tracked crayfish occurred within 2 days of release. After this time, periods of residence were interspersed by movements to new locations, interpreted as establishment of ephemeral home areas. It is suggested that the initial large movements were the result of a ‘fright response’ following capture.
• 4 Movements varied widely between individuals, some moving more than 300 m in 10 days, while others showed little movement over an equivalent time period. Mean (±SE) daily movements were 4.6 ± 3.0 m for males and 1.5 ± 1.0 m for females. Although crayfish often used specific home sites for in excess of 7 days, displaced animals did not return to home sites.
• 5 The total distances travelled and the mean distance travelled per day by individual radio‐tagged crayfish did not differ significantly between upstream or downstream directions or between males and females. This was also the case for marked crayfish used in mark‐recapture studies.
• 6 Positive correlations between distance moved per day and size (carapace length) were found for downstream movements by male and female crayfish, but not for upstream movements.
• 7 Some preliminary observations of the response of crayfish to flood events suggested that these could be catastrophic with two out of five tracked crayfish found dead after a high stream‐discharge event.

     

Large scale Agriotes spp. click beetle (Coleoptera: Elateridae) invasion of crop land from field margin reservoirs

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Population dynamics of the japanese clouded apolloParnassius glacialis butler (Lepidoptera: Papilionidae). I. changes in population size and related population parameters for three successive generations

1. Population dynamics of a univoltine butterfly Parnassius glacialis (Lepidoptera: Papilionidae) was studied with mark-recapture methods for three successive generations in a hilly region in Kanazawa City, Ishikawa Prefecture, Japan in 1981–1983.
2. Jolly (1965) andSeber's (1973) method was applied to the mark-recapture data to estimate population parameters (daily survival rate, longevity, population size, sex ratio, etc.).
3. Sampling ratios were at least 50% and 30% for males and females, respectively.
4. Mean daily survival rate for males ranged 0.81–0.86 and that for females 0.80–0.84. Mean longevity was about 4–7 days for the males and about 5 days for the females. Spiders killed more males than females. Maximum longevity for an individual recorded during the study was 31 days for males and 18 days for females.
5. Emergence of the butterflies was later and less synchronous in 1981 than in 1982 and 1983. This was thought to be due to later extinction of heavier snow in 1981 than in the other years.
6. The population remained relatively stable for the three successive generations, with estimated total numbers of 914, 1277, and 869.
7. Estimated sex ratio (% females) was 30–40% at emergence

     

Physiological correlates of the availability of Glossina morsitans centralis Machado to different sampling methods

Abstract.

• 1 The feeding cycle for male tsetse flies and the pregnancy cycle for females are used as frameworks for investigating the field behaviour of Glossina morsitans centralis Machado in Zambia, and hence the sampling biases of different capture devices.
• 2 Flies were collected in the field using hand nets and an electric back pack on foot patrols, and hand nets, hand-catching and an electric screen on landrover patrols. They were analysed for wing-fray, vein-length, chloroform-extractable fat and haematin. In addition, samples of laboratory-bred females killed daily during their second pregnancy cycle were analysed for the last two parameters.
• 3 The daily flying time of males is estimated from the fat—haematin curve to be about 32 min/day, which is identical to previous estimates for G. morsitans from Tanzania.
• 4 From the varying numbers and fat content of male flies caught by the different sampling methods during the course of the feeding cycle it is concluded that both haematin levels and fat reserves influence fly behaviour.
• 5 Comparison of the frequency distribution of wild-caught and laboratory-bred females along the corrected residual dry weight axis of the pregnancy cycle suggests that the results of combined electric-trap and hand-net sampling reflect the actual frequency distribution in the wild population at least for the first 7 days of the pregnancy cycle; but females in the last 2 days of their pregnancy cycle are apparently unavailable to sampling devices, perhaps because of their reduced flight activity.
• 6 The very variable percentage female catch (10.9–43.4%) returned by the different sampling methods is discussed in the light of the detailed analysis of the differential availability of male and female flies to each capture device.

     

Population structure in the small ermine moth Yponomeuta padelus: an estimate of male dispersal

Abstract.

• 1 An extensive investigation was carried out into the structure of a large, effectively continuous population of Yponomeuta padellus Latreille, feeding on hawthorn, Crataegus monogyna, and blackthorn, Prunus spinosa.
• 2 Mark—recapture studies were used to obtain direct estimates of the male dispersal rate, σ, in two successive years.
• 3 Dispersal was found to be extremely localized with respect to the total area of the study population. Estimates of u ranged from a minimum of 2.47 m to a maximum of 12.5 m.
• 4 Limited dispersal could be an important factor governing the genetic differentiation of Y.padellus populations, and its implications for the supposed existence of host races in this species are discussed.

     

Distribution and spacing of Drosophila mycetophaga flies on bracket fungi used as mating arenas

Abstract.

• 1 To understand the nature of male aggregations in Drosophila mycetophaga, data were collected on male and female distribution and male spacing on bracket fungi used as mating arenas in cool rainforests of south-eastern Australia.
• 2 Both males and females appeared to be aggregated among bracket fungi that were used as mating arenas. Females were associated with large male aggregations. The probability of a fungus being occupied increased with its area. However, a multiple Poisson regression analysis suggested that fungus area did not affect female distribution when male number was controlled.
• 3 The presence of female breeding and feeding resources did not determine where aggregations were formed, because there were aggregations on fungi without resources, and fungi with resources were not used more often than those without them.
• 4 D.mycetophaga males did not select and defend territories within bracket fungi, and did not determine female access to areas. However, males were more evenly spaced than expected on the basis of a random distribution, suggesting that males kept apart from each other.
• 5 The distribution of the different sexes and male spacing pattern supports the interpretation that D.mycetophaga has a lek mating system.

     

A population study in Jamaica on adult Sceliphron assimile (Dahlbom) (Hymenoptera: Sphecidae)

Abstract.

• 1 A mark–recapture study on the sphecid wasp Sceliphron assimile (Dahlbohm), analysed by Jolly's stochastic method (1965), was made from 3 December 1974 to 22 February 1975 at Green Bay, St Catherine, Jamaica.
• 2 Population levels in an 18.2 ha study area fluctuated about a mean of 281 for males, 259 for total females and 87 for reproducing females, while the probable carrying-capacity for these reproductives was about 104.
• 3 Mean estimated daily survival rates were 0.903 for males, 0.924 for total females and 0.945 for reproducing females. For the first two categories these rates decreased (p < 0.02) during the study, probably reflecting increasing emigration. Reproducing females probably do not emigrate and their survival did not significantly decrease.
• 4 Minimum age was linearly related to wing wear (r=+0.69, P < 0.001) and the latter associated with the progressive maturation and ageing of the ovaries. All surviving females become parous by middle age.
• 5 The mean rate of fecundity in the field was dependent on female age and was reduced during prolonged drought. Curves of total achieved fecundity appropriate to realistic survival rates give 4.2–16.8 eggs/female. The Jamaican mean was 9.6 ± 2.3 and that for Green Bay 8.6.
• 6 The proportion of females in the Green Bay population was 0.48 ± 0.03 while 0.55 was expected at emergence.
• 7 A cyclic budget is used to estimate immigration and emigration, and these were important causes of population change.
• 8 For Jamaica, only an estimated 28% of females survived to nest.

     

Oviposition choice and larval survival of Dasineura marginemtorquens (Diptera: Cecidomyiidae) on resistant and susceptible Salix viminalis

Abstract.

• 1 Substantial intraspecific variation exists in Salix viminalis resistance to the gall midge Dasineura marginemtorquens. Earlier work has found this variation to have a large genetic component. Willow clones are stable in their resistances between midge generations and different nutrient levels in both field and laboratory culture.
• 2 This study reports the results of laboratory experiments on female oviposition choice and larval survival on potted plants from clones that are very different in resistance as determined in field studies.
• 3 In choice experiments using pairs of plants, the average female midge did not prefer susceptible willow clones over resistant ones for oviposition. In about one third of the replicates, midges actually laid more eggs on the resistant clone. Further work is necessary to examine the nature of variation among midges in discrimination of these plant types.
• 4 Resistance is manifested as great differences in larval survival. Six days after oviposition survival was 92% on susceptible plants but only 6% on resistant ones. Galls developed on all of the susceptible plants, while in 73% of the resistant plants galls were not even initiated.
• 5 The plant traits causing resistance are enigmatic. Larval behaviour suggests that resistant plants interfere with feeding behaviour. On resistant plants, most larvae wander for more than 24 h without initiating any galls before dying. On susceptible plants many first instar larvae begin feeding and initiate galls within this period.

     

The biology of the phonotactic parasitoid, Homotrixa sp. (Diptera: Tachinidae), and its impact on the survival of male Sciarasaga quadrata (Orthoptera: Tettigoniidae) in the field

Abstract.

• 1 Unlike most parasitoids, tachinid flies of the tribe Ormiini use sound to locate their hosts. Although thought to exert selection pressure on their host's calling behaviour, little is known about the biology of ormiines. Accordingly, this study reports the biology and impact of the ormiine Hornotrixa sp. upon calling males of the univoltine bushcricket Sciarasaga quadrata Rentz in south-western Australia.
• 2 Populations of adult S.quadrata were monitored in the field over two successive calling seasons. Females, which do not call, were not parasitized by Hornotrixa sp., but the risk of parasitism for males increased as the 3-month calling season progressed. Parasitism did not commence until c. 2 weeks into the calling season, but by the end of the season up to 87% of surviving males were parasitized.
• 3 Parasitized males lived for 14 days and were found singing until their penultimate evening before death in the field. Unparasitized males lived on average 69 days and a maximum of 119 days.
• 4 Multiparasitism of hosts was common, with up to sixteen fly larvae found within parasitized males. The number of fly larvae within hosts significantly increased at the end of the season. However, successful emergence of fly larvae from hosts, as well as pupal size, significantly decreased as more than one fly larva developed within the host.
• 5 Hornotrixa sp. has a long pupal duration of 30–31 days at 20°C. As a consequence, only one complete fly generation, which overwinters in the pupal stage, is likely within each host generation.
• 6 No evidence for differential (size-bias) mortality by Hornotrixa sp. on male S.quadrata was found. The size of parasitized and unparasitized males collected in the field was not significantly different.
• 7 It is concluded that Hornotrixa sp. is a significant mortality factor acting on the survival of adult male S.quadrata.

     

Characteristics of dispersal in sexually mature dragonflies

Abstract.

• 1 The population dynamics of a natural population of Sympetrum danae (Sulzer) were studied, by means of a mark—release—recapture method, to find indications of dispersal by mature adults. Additional information on orientation and the influence of phenotype (including age), density and weather was obtained by observations under natural conditions and in a large outdoor field cage.
• 2 80% of all mature adults caught around the natural pond were estimated to be immigrants. Considerable immigration was confirmed by the abdomen length of unmarked matures which did not accord with that expected from the locally emerged population. Total numbers captured and the minimum number known to be alive fell sharply at the time when most individuals were mature. At the same time, new matures continued to enter and disappear from the study area at an increasing rate.
• 3 Dispersive behaviour (escape flights) in the field enclosure was primarily age dependent in both sexes: it occurred from an age of 25–30 days onwards. This coincides with the time-lag between the emergence peak and increased dispersal in the field. Secondary effects on escape flights suggested that males tended to abandon low density areas.
• 4 Males flew relatively more southward than females.

     

A field evaluation of the sexual competitiveness of sterile melon flies, Dacus (Zeugodacus) cucurbitae

ABSTRACT.

• 1 The sexual competitiveness of sterile melon fly males [Ducus (Zeugodacus) cucurbitue Coquillett] was estimated under field conditions.
• 2 The value of competitiveness was about 0.8 for flies in the fifth to tenth generation from the beginning of mass-rearing, but decreased to about 0.2 in the eighteenth generation.
• 3 The sexual competitiveness estimated using laboratory data was near unity even in the final stage of our study.
• 4 It was concluded that the field evaluation of sexual competitiveness is essential to determine the quality of the insects reared for purposes of pest control.

     

Protected raspberry production accelerates onset of oviposition by vine weevils (Otiorhynchus sulcatus)

• 1 Soft fruit production is increasingly reliant on crops that are grown under the protection of plastic tunnels, which may also affect insect communities as a result of localized climate change and changes to host plant physiology and chemistry. In particular, insect development rates may differ from field populations, making it more difficult to target control measures.
• 2 The present study investigated how protected environments affected adult vine weevil (Otiorhynchus sulcatus) feeding and reproduction on red raspberry (Rubus idaeus). We focused on the period between adult emergence and the onset of oviposition (i.e. the pre‐reproductive period), which represents the optimal period for control.
• 3 Tunnels were up to 4 °C warmer than field plantations in 2008, with plants growing significantly faster (50% increase in height and 16% increase in leaf area) than field grown plants. The carbon/nitrogen ratio in leaves was higher in tunnels (12.07) than the field (10.89) as a result of a significant decrease in nitrogen concentrations (3.40 and 3.90 mg g^?1, respectively).
• 4 Over 4 weeks, weevils consumed significantly more foliage in tunnels (370.89 mg) than weevils in the field (166.68 mg), suggesting compensatory feeding to counteract lower leaf nitrogen concentrations. Weevils in tunnels achieved sexual maturity 8 days earlier than those in the field and produced 20‐fold more eggs by the time they were 5 weeks old.
• 5 Applying a degree‐day model showed good agreement between predicted and observed pre‐reproductive periods for weevils in tunnels (36 and 30 days, respectively) and in field plots (41 and 38 days, respectively).

     

Optimising control of invasive crayfish using life‐history information

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Temptations of weevil: feeding and ovipositional behaviour of Hylobius warreni Wood on host and nonhost bark in laboratory bioassays

• 1 Warren root collar weevil Hylobius warreni Wood (Coleoptera: Curculionidae) is a long‐lived, flightless insect native to coniferous forests across northern North America. Girdling by larval feeding causes significant mortality on young trees. The insect poses considerable challenges to reforestation.
• 2 Adult weevils feed on all life stages of a variety of coniferous hosts prior to oviposition. Their relative feeding preferences, however, have not been quantified. Moreover, it is not known whether host bark influences oviposition behaviour.
• 3 Feeding preferences of adult weevils were tested in both choice and no‐choice laboratory bioassays using small branches from three conifers (lodgepole pine Pinus contorta var. latifolia, interior hybrid spruce Picea glauca×engelmannii, and Douglas‐fir Pseudotsuga menziesii) and one deciduous tree (trembling aspen Populus tremuloides). Measurements included the surface area of bark consumed, rate of consumption, the number of days of feeding, and, in the no‐choice assay, the number of eggs oviposited.
• 4 Bark consumption was greatest on pine and Douglas‐fir, followed by spruce. Little to no feeding occurred on aspen. Consumption did not vary between male versus female insects for any of the feeding metrics quantified.
• 5 The presence of aspen branches did not inhibit feeding on any of the other species in the choice bioassays.
• 6 The number of eggs laid by female insects did not differ significantly among tree species in the no‐choice assay. Eggs were laid indiscriminately in the presence of all four host types.
• 7 Results and opportunities for future research are discussed in the context of formulating new integrated pest management strategies for this insect, which is increasingly important in the period of reforestation subsequent to the mountain pine beetle epidemic in western Canada.

     

Native European eels as a potential biological control for invasive crayfish

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Adult movements between populations in the specialist butterfly Proclossiana eunomia (Lepidoptera, Nymphalidae)

Abstract.

• 1 The structure of local populations of a monophagous butterfly, the bog fritillary Proclossiana eunomia, was studied in a complex of suitable habitat patches separated by spruce plantations or fertilized pasture.
• 2 An unexpected high level of adult movements between habitat patches was detected by a mark—release—recapture technique. Local populations were connected by adult movements across unsuitable habitats, leading to a meta-population structure.
• 3 This evidence of the metapopulation structure of a specialist butterfly challenges the supposed relationship between habitat specialization and closed, isolated populations.
• 4 Males and females of P.eunomia exhibited different spatial behaviours; females were more likely to emigrate and dispersed further than males. These differences in spatial behaviour are related to the mating system.

     

Studies on Chironomidae in experimental recirculating stream systems. II. The growth, development and production of a spring generation of Orthocladius (Euorthodadius) calvus Pinder

SUMMARY.

• 1 Orthodadius (Euorthodadius) calvus Pinder. similar to Orthocladius (Euorthodadius) thienemanni Kieffer. colonized a new gravel substratum in two recirculating stream channels. A maximum population density of 68.621 m^-2 was attained after only 16 days. This had fallen to a negligible density by the thirty-third day.
• 2 Some recruitment occurred over most of the study period (April-May 1981) and no single sharply defined cohort was evident. There was a large range of body lengths within each instar. and considerable overlap between instars. The population density estimates for instars I and II were low compared with instars III and IV.
• 3 The relationship between instantaneous growth rate (g) and geometric mean length indicated that growth was best described by a Gompertz curve. Growth rate decreased with increasing length from a value of about 40% length day^-1 at 2 mm body length to about 5% length day^-1 at 9 mm.
• 4 Growth rates for individual larvae, kept in culture, were very variable with maximum rates close to the values determined from the field data. Mean duration of larval life was 16 days.
• 5 Estimates of production for the study period ranged from 13.5 g dry wt m^-2 (Channel III, size-frequency method) to 34.2 g dry wt m^-2 (Channel II, Allen's graphical method, values corrected for non-linear growth).
• 6 Gut contents were estimated to represent about 55% of the total weight therefore production values should be reduced by this amount.