Temperature Threshold For Flight Research Articles

Thermal limits for flight activity of field-collected Culicoides in the United Kingdom defined under laboratory conditions

BackgroundCulicoides biting midges (Diptera: Ceratopogonidae) are biological vectors of internationally important arboviruses and inflict biting nuisance on humans, companion animals and livestock. In temperate regions, transmission of arboviruses is limited by temperature thresholds, in both replication and dissemination of arboviruses within the vector and in the flight activity of adult Culicoides. This study aims to determine the cold-temperature thresholds for flight activity of Culicoides from the UK under laboratory conditions.MethodsOver 18,000 Culicoides adults were collected from the field using 4 W down-draught miniature ultraviolet Centers for Disease Control traps. Populations of Culicoides were sampled at three different geographical locations within the UK during the summer months and again in the autumn at one geographical location. Activity at constant temperatures was assessed using a bioassay that detected movement of adult Culicoides towards an ultraviolet light source over a 24-h period.ResultsThe proportion of active adult Culicoides increased with temperature but cold temperature thresholds for activity varied significantly according to collection season and location. Populations dominated by the subgenus Avaritia collected in South East England had a lower activity threshold temperature in the autumn (4 °C) compared with populations collected in the summer (10 °C). Within the subgenus Avaritia, Culicoides scoticus was significantly more active across all temperatures tested than Culicoides obsoletus within the experimental setup. Populations of Culicoides impunctatus collected in the North East of England were only active once temperatures reached 14 °C. Preliminary data suggested flight activity of the subgenus Avaritia does not differ between populations in South East England and those in the Scottish Borders.ConclusionsThese findings demonstrate seasonal changes in temperature thresholds for flight and across different populations of Culicoides. These data, alongside that defining thresholds for virus replication within Culicoides, provide a primary tool for risk assessment of arbovirus transmission in temperate regions. In addition, the study also provides a comparison with thermal limits derived directly from light-suction trapping data, which is currently used as the main method to define adult Culicoides activity during surveillance.Graphical

Flight initiation of Nysius huttoni (Hemiptera: Orsillidae) in relation to temperature and wing forms

Flight initiation of the New Zealand wheat bug, Nysius huttoni White, in relation to temperature and wing forms was studied in the field over a period of 4 years. The results indicated that temperature is a major factor affecting flight initiation of this species. When air temperature rose to 27 °C, and/or the ground temperature reached 40 °C, flights occurred. These two temperatures are determined as thresholds for flight initiation. Flights were short, low and hop-like, covering up to five metres. Flight behaviour is displayed by a portion of individuals of a population in response to high temperature, suggesting that other factors are involved. Flight can occur in adults of any generation except overwintered generation depending on ambient temperature, but mainly in those of second and third generations. Daytime flight is common, peaking especially around midday with high temperatures. Macropterous and sub-brachypterous forms are capable of flight, whereas the brachypterous form is apparently flightless. Both sexes of flying adults have the same temperature thresholds for flight.

Species Abundance and Seasonal Activity of Mosquitoes on Cattle Facilities in Southern Alberta, Canada

Seventeen mosquito species were collected at eight cattle facilities in southern Alberta, Canada, during 2002-2004. Five species, Culiseta inornata (Williston), Aedes dorsalis (Meigen), Culex tarsalis (Coquillett), Aedes vexans (Meigen), and Aedes campestris Dyar & Knab accounted for 93.6% of the mosquitoes collected. Culiseta inornata, Ae. dorsalis, and Ae. campestris were trapped earliest in the year. Cs. inornata was active latest in the year and had the longest period of activity. Ae. dorsalis finished activity in late September and had the second longest period of activity. Ae. campestris was the first to complete its activity, resulting in a moderate period of activity. Cu. tarsalis and Ae. vexans appeared later in the season, disappeared by late September, and had the briefest periods of activity. Logistic regression was used to estimate relationships between the proportions of traps positive and mean weekly abundance for each species. Fifty percent of the traps were positive when abundance averaged 0.19-0.30 females per trap night. Logistic regression was used to determine the timing of the onset of activity and temperature thresholds for flight. Relationships between the proportion of positive traps and mean weekly temperature indicated that Cs. inornata had the lowest temperature threshold, Cx. tarsalis the greatest, and the remaining species had intermediate thresholds. Logistic regression indicated that mosquito presence was primarily affected by temperature and accumulated degree-days, with only Ae. vexans exhibiting a positive response to precipitation. The models can be used to predict the onset of activity as defined by when populations exceed a particular threshold.

Thermal requirements for flight of six species of flea beetle of the genus Phyllotreta (Coleoptera: Chrysomelidae)

The flight activity of six species of the flea beetles of the genus Phyllotreta was monitored by means of yellow water traps in three years. The percentage composition of the total catch of adults made up of the species was 29.5% (P. vittula), 28.8% (P. atra), 17.5% (P. undulata), 12.8% (P. nigripes), 7.1% (P. vittata) and 4.3% (P. nemorum). The flight activity of each species had two peaks. The spring peak was made up of overwintering adults migrating to host plants, and the summer peak of newly emerged adults. A regression model of flight activity in both generations was established based on the sum of day degrees above the temperature threshold for flight (10.2°C). The onset of flight activity of adults of the overwintering generation in spring started at 30 day degrees, and that of the adults of the summer generation at 280 day degrees. These temperature requirements for flight activity indicate when best to inspect crops for effective pest management.

The relative performance of pheromone and light traps in monitoring the seasonal activity of both sexes of the eastern hemlock looper, Lambdina fiscellaria fiscellaria

AbstractThe seasonal flight activity of both sexes of the eastern hemlock looper, Lambdina fiscellaria fiscellaria Guenée (Lepidoptera: Geometridae) was studied during two consecutive years in Quebec and Newfoundland, using light (L), pheromone (P) and combined light and pheromone (LP) traps. Moth density significantly affected the performance of the different traps, with P traps being more effective at low than high density. However, P trap catches decreased just prior to the onset of female captures, probably as a result of competition between traps and virgin calling females. Nearly all females caught in L and LP traps were already mated and even the first females caught had laid at least half of their egg complement. In Quebec under warm nights, the pattern of male activity occurred at different times, with peak P catches being later in the scotophase than those of L traps, but overall similar numbers of males were caught in both traps. In contrast, under cool nights, males were caught early in the night in both P and L traps, suggesting a strong competition effect between traps, although more males were caught in P than L traps overall. In Newfoundland, the pattern of male captures in L and P traps was similar at both high and low temperatures, so competition between trap types would always be high. Under these conditions P traps were more effective than L traps. Irrespective of the region, year or temperature, significantly more males were captured in LP, with the effect of L and P being additive. In both regions, females responded similarly to L and LP traps with peak activity occurring early in the night. Captures of females were lower than those of males under cool temperatures, suggesting that the temperature threshold for flight is higher for females. The use of L and P traps simultaneously and/or in combination is discussed in relation to integrated pest management programs and ecological considerations.

Flight Initiation of Lesser Grain Borer (Coleoptera: Bostrichidae) as Influenced by Temperature, Humidity, and Light

The rate that stored-product insects migrate by flight into a grain storage facility is influenced by environmental conditions that mediate flight activity. The influence that temperature, humidity, and light intensity have on the initiation of flight by the lesser grain borer, Rhyzopertha dominica (F.), was examined in the laboratory. Flight initiation by male and female beetles up to 8 wk old was examined. Lower and upper temperature thresholds for flight were calculated to be 19.9 and 41.6°C, respectively. Humidity did not influence /light initiation within this temperature range. The optimal temperature resulting in the highest percentage of flights was 30.7°C. Male and female R. dominica flight activity was similar. Greatest flight activity occurred in beetles up to 1 wk old, whereas older adults exhibited little flight activity. This suggests that, once R. dominica infest a bulk of grain, they tend to stay and reproduce rather than leave. Migration by flight is possible during the summer when wheat is harvested and stored, but temperatures may limit migration in fall when corn and sorghum are harvested or wheat is aerated. Early fall aeration when temperatures are >20°C could cause R. dominica to be attracted to volatiles emanating from the bin.

Temperature Thresholds for Spring Emergence and Flight of the Boll Weevil 12

A strong relationship was found between temperature and emergence of boll weevils from overwintering sites. The threshold temperature above which overwintering weevils accumulated heat units was 10.85°±1.3°C. Early fall cohorts required a higher number of accumulated heat units than did late fall cohorts. First-emerging weevils of early cohorts had a lower tendency to subsequently initiate flight activity than did first-emerging weevils of later cohorts. The temperature threshold for flight of 95–98% of newly emerging weevils was 20°C.

Rate and Thresholds of Boll Weevil 1 Locomotory Activity in Response to Temperature 2

Boll weevils collected from pheromone traps and newly eclosed adults were tested for locomotory activity at various temperature and light-dark conditions. Greater flight activity was observed during the light than dark cycle for pheromone trapped and boll reared weevils. Light-dark conditions did not appear to affect walking activity. Temperature thresholds for flight and walking averaged 14.0° and 2.6°C, respectively.

Dispersal, seasonal flight activity and winter survival of the oak stem Phylloxerid Moritziella corticalis (Kalt.) (Homoptera, Phylloxeridae)

AbstractThe dispersal and seasonal flight activity of the oak stem Phylloxerid (Moritziella corticalis (Kalt.)) was studied at three localities in southern England by means of field observations and by sticky trap and suction trap catches. Wind displacement of first-instar crawlers occurred mainly during the winter months (76.2%) when this stage of the life-cycle is most active and abundant. No desiccation of these larvae was observed. The flight period of the sexuparae extends from the end of July to the end of October, and in most years three peaks of flight activity were discernible. A succession of days with low temperatures sometimes prevented migration, but large catches usually followed these low temperature spells. Analysis has shown that the temperature threshold for flight was about 17·2°C. Individuals flying at the start of the flight period were significantly smaller than those flying at the end of the season, possibly because factors affecting the host-plant may also effect changes in breeding and development of the insect. In a frost gradient apparatus, the overwintering first-instar larvae of M. corticalis were cold hardy, the LT30 being -23·7°C.

Field Observations on Adults of the Wheat Bulb Fly (Leptohylemyia coarctata (Fall.)).

A study of adult populations of Wheat Bulb Ply, Leptohylemyia coarctata (Fall.), has been carried out in the field by routine sweeping at Rothamsted. It has been observed that the males emerge slightly before the females and that the emergence period may cover at least three weeks in late June and early July. Although the number of males may exceed the number of females at first, the females predominate later in the season due to the shorter life span of the males.The numbers of flies on the wheat have been found to fluctuate appreciably throughout the day. During the first week of the emergence period the number of flies taken increased steadily throughout the day. After the date of population peak, however, the maximum numbers occurred in the crop in the very early morning and the late evening, which suggested a daily flight dispersion followed by a general or localised return of the flies to the crop. Further study of the data showed that the daily temperature rhythm was only partly responsible for this daily flight dispersion, and that there appeared to be an active return flight to the crop in the evening. Generally the males were more active than the females and did not settle so deeply in the crop.The temperature threshold for flight was observed to be 12 to 13°C. Winds up to 8 m.p.h. did not appear to affect flight activity, but higher winds, e.g., 15 m.p.h., markedly reduced flight, the flies remaining deep in the crop near ground level. Gale-force winds, however, were observed to produce a permanent depletion in the number of flies infesting Broadbalk field, indicating that the population was probably localised.Although portions of the populations dispersed fairly rapidly from the emergence sites, recaptures of radioactive flies labelled with 32P indicated that the extent of the dispersions was not very great. The females dispersed more than the males, and were influenced to some extent by the occurrence of wheat in flower. Frequently the flies were found to have congregated on the lee edge of the crop, but other preferred regions have been observed which could not be attributed to the influence of the wind.