Day-degree models for predicting the generation time and flight activity of local populations of Lobesia botrana (Den. & Schiff.) (Lep., Tortricidae) in Greece

The generation time of Lobesia botrana (Den. & Schiff.) was estimated as the number of day-degrees required between the start of a flight and the start of the following flight in two regions in northern Greece. The day-degrees required for the first generation ( x =339.3, Naoussa; x =275.6, Thessaloniki) were significantly shorter than for the second ( x =751.5, Naoussa; x =833.8, Thessaloniki) and the third generations ( x =899.5, Naoussa; x =1197.0, Thessaloniki). Nonlinear models were developed using trap catches of male L. botrana during 1987–1989 for predicting its flight activity. A lower threshold temperature of 6.45°C was used in calculating daily day-degrees from 1 March. The models predicted with sufficient accuracy the accumulated male moth catch and they accounted for the 60–78% and 86–91% of year-to-year variation in male flight activity in Thessaloniki and Naoussa, respectively.     

Effects of heat on the dispersal performance of Ips typographus

Under present climate conditions, Ips typographus (L.) is Europe's most critical disturbance agent for mature Norway spruce (Picea abies). With ongoing climate change, the bark beetle will most probably become more prominent as a pest. The aim of this study was to analyse the dispersal performance of I. typographus under various weather conditions, especially hot days with a maximum air temperature above 30°C. In a field study, marked bark beetles were released from breeding logs and could be retraced in traps distributed across the survey area. With daily collections of the trapped beetles, it was possible to analyse the flight activity and the average flight distance of the bark beetles during hot, moderate and cool days. The numbers of daily catches and the average flight distance during the hottest days (air temperature maximum ≥30°C) did not significantly differ from the moderate days (air temperature maximum ≥22°C and <30°C). The numbers of daily catches and the average flight distance during the cool days (air temperature maximum <22°C) were significantly lower than during hot and moderate days. The results give an insight on the dispersal capacity of I. typographus under climate change driven future conditions. Increased air temperatures do not seem to impair the flight performance of I. typographus. A small proportion of cool days during the swarming period even seems to favour dispersal of I. typographus.     

An empirical predictive model for the flight period of Platypus koryoensis (Coleoptera: Platypodinae)

Between 2007 and 2009, field studies were conducted in four Quercus mongolica Fischer ex Ledebour forests in Korea to develop an empirical degree-day model for the flight period of the ambrosia beetle, Platypus koryoensis (Murayama). The lower developmental threshold temperature was estimated using an iterative method based on field trap catches and temperatures. The pooled proportion of the total number of beetles found in the traps at the end of the experiment was plotted against the accumulated degree-days at selected baseline temperatures, and these plots were fitted by the Weibull function. The baseline temperature with the highest coefficient of determination was considered the lower developmental threshold temperature, and this was estimated to be 5.8 °C. The explanatory power of the model was 89 %. Moreover, the model accurately predicted the time distributions of P. koryoensis flights in 2011 and 2012 at one of the sites. The estimated median flight dates in 2011 and 2012 were 4 days earlier and 5 days later than the corresponding observed flight dates, respectively. The estimated median date of flight advanced progressively during 1970–2010 by a total of 9 days due to an increase in annual mean temperature.     

The effect of temperature and wind on the flight activity of cereal aphids

The lower temperature threshold for take-off in Sitobion avenae obtained from an analysis of daily 12·2 m suction trap catches was 16°C. In the laboratory, the take-off threshold for S. avenae was 17·5°C in increasing temperatures, but 19°C when aphids were kept at constant temperatures for a short period of time. The equivalent thresholds were both 20·5°C for Metopolophium dirhodum. Over a period of 16 h no S. avenae took-off from plants at 10°C, 70% at 15°C and all within 16 h at 20°C. It was concluded that suction trap catches can be used to compare the temperature thresholds for take-off of both different species and morphs of a species of aphid. Emigrants of Rhopalosiphum padi, but not of M. dirhodum, took-off at a higher temperature than the alate exules. High winds were found to delay but not inhibit take-off both in the field, and in the laboratory, using both artificial and plant substrates. All aphids eventually flew, even from favourable hosts. It was concluded that adverse weather conditions will delay but not prevent cereal aphid migration in early summer.     

Temperature accumulation and physiological ageing of seed potato tubers

Tubers of cv. Maris Bard were allowed to accumulate different numbers of day-degrees early, late or continuously throughout the seed storage period. Sprout growth, time of emergence, development of early canopy cover and early tuber yield were increased more by late temperature accumulation than by increasing the number of day-degrees experienced from 250 up to a maximum of 700°C days. The relative physiological age of seed, as indicated by the subsequent rate of early crop growth, was poorly related to the number of day-degrees accumulated. The implications for the quantification of seed physiological age are discussed.     

Egg Development in the Stonefly Pteronarcys californica Newport (Plecoptera: Pteronarcyidae)

Eggs of Pteronarcys californica Newport were incubated at fixed temperatures between 5 and 20°C in the laboratory and at field temperatures in the Crowsnest River, Alberta. The regression of rate of development on temperature between 5–15°C gave a developmental zero of 3.125°C. Within the range 10–20°C, highest hatching success and fewest days to median hatch occurred at 15.0 or 17.5°C, but physiological time (day-degrees) for egg hatching increased with temperature throughout, markedly so above 15°C. A minimum of 182 days was required for 50% hatch in the laboratory, with no observable development for approximately 80 days. Eggs placed in the river on 25 May 1993 started to hatch on 17 October 1993, and the pulse of larval recruitment in the field population occurred between April and August, 11 to 15 months after oviposition. Eggs hatched over periods of 130–322 days at different temperatures in the laboratory, and over an 11-month period in the field. The placement of diapause early in embryonic development is suggested as a cause of extended recruitment. The variety of embryonic development in Plecoptera is briefly reviewed.     

Ascospore Discharge and Survival in Pseudopezicula tracheiphila, Causal Agent of Rotbrenner of Grape

A recording volumetric spore trap was operated continuously amidst overwintered grape leaves in a vineyard at Walenstadt, Switzerland from early May to mid-July 1988. Ascospores of Pseudopezicula tracheiphila were captured in the air beginning 11 May and 96 % of the total seasonal release occurred between 16 May and 2 June. Rain always preceded ascospore release. However, trap catches were associated with the simulataneous cessation of rainfall, decreased relative humidity (RH), increased temperature, and drying of foliage. Maximum ascospore release occurred in the second hour, following commencement of drying. Ascospores discharged dry onto glass coverslips survived with greater than 60 % viability after 1, 3, and 6 days exposure to 10, 15, 20, and 25°C at 70 % RH. Only at 30°C was viability reduced to slightly less than 50 % after 6 days.     

Pheromone-trap catch in relation to the phenology of codling moth (Cydia pomonella)

Relationships between a pheromone-trap catch, adult emergence and penetration of fruit by first-instar larvae of Cydia pomonella were investigated from 1975 to 1977 in an orchard in South West England. For the first generation the times of moth emergence and catch in the pheromone trap were not significantly different; nor were male and female emergence times. The catch of moths of the first generation in the pheromone trap anticipated the appearance of their larvae in the fruit by 140–169 day-degrees > 10 °C. Eggs hatched after 94 day-degrees in the laboratory but in the orchard, wind and sunshine modified the microclimate so that the number of day-degrees required for egg development, as measured by standard meteorological instruments, was affected by wind and sunshine but development lasted on average about 90 day-degrees. This indicated a lag of 50–80 day-degrees between the curves for trap catch and oviposition: the pre-oviposition period in the orchard was shorter than expected from laboratory studies. In 1975 and 1976, some larvae developed to produce a second generation of moths which gave rise to a second generation of eggs and larvae, after an interval of 161 day-degrees in 1975, but only 41 day-degrees in 1976, indicating that in 1976 some eggs were laid before moths of the second generation were trapped. These results indicate that the first insecticidal spray against first-generation larvae should be applied about 140 day-degrees after the start of the reference week in which five moths of the spring brood are caught per trap. A second spray, if required to maintain insecticidal cover, should be applied about 100 day-degrees later. A spray should be applied against second-generation larvae immediately after the reference week for second-generation moths.     

Diurnal flight pattern of Platypus koryoensis (Coleoptera: Platypodinae) in relation to abiotic factors in Korea

The diurnal flight pattern of Platypus koryoensis (Murayama) was examined using sticky traps attached to the trunks of oak trees in central Korea in 2010 and 2011. The flight activities of the beetle were estimated on the basis of 3-h intervals for trap catches from 11:00 to 14:00 on the next day, on June 25–26 and July 1–2, 2010, and on the basis of 2-h intervals for trap catches from 5:00 to 17:00, between June 9 and July 21, 2011 (the peak flight period of the beetle). Over 77% of the beetles were caught from 9:00 to 13:00, with the daily variations in the facing slope. The beetles began to be caught when the air temperature reached around 16 °C, and were the most active when the temperature ranged from 20 to 27 °C. No beetles were caught during rainfall, suggesting that rainfall is one of the factors that hinder beetle flight. The beetles were caught by traps in the east-facing plot earlier than those in the south- and west-facing plots suggesting that the flight behavior of the beetle can be affected by the light. Direction of the beetle flight during the peak of daily flight (from 09:00 to 13:00) was downward along the slope.     

Can observation of climatic variables be used to predict the flight dispersal rates of Prostephanus truncatus?

Abstract 1 Attack by Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) on the maize and cassava stored by small‐holder farmers in Africa is sporadic, varying considerably within and between years. The risk that food in store will become infested is related to the number of beetles dispersing by flight. A means of predicting years with high dispersal rates is needed to warn farmers when to be vigilant. 2 The relationship between climatic variables and pheromone trap catches was observed in a forest‐savannah transition zone in Ghana. These observations were used to devise a model using a mix of biological and empirical rules that operate on temperature and humidity data. The predicted and actual trap catch deviated by only +5% to ?1% in years when there were high dispersal rates. 3 The first part of the model estimates the numbers of beetles with potential for dispersal. The second part predicts the proportion likely to disperse. This is based on the apparent effect that those P. truncatus developing under low temperature conditions (about 24 °C) have a lowered propensity for flight, a response previously observed in a related species. 4 The model was validated using climate data and trap catches from a woodland–savannah zone and a short grass steppe zone. With minor adjustment, the model worked well for these two habitats.     

Assessing the effects of low temperature on the establishment potential in Britain of the non-native biological control agent Eretmocerus eremicus

Abstract. Eretmocerus eremicus is a parasitoid wasp that is not native to Britain. It is a biological control agent of glasshouse whitefly and has recently been released under licence in Britain for the first time. This study assessed the effect of low temperature on the outdoor establishment potential of E. eremicus in Britain. The developmental threshold calculated by three linear methods was between 6.1° and 11.6 °C, with a degree‐day requirement per generation between 256.3 and 366.8° day^?1. The supercooling points of non‐acclimated and acclimated larvae were similar (approximately ?25 °C). Non‐acclimated and acclimated larvae were subject to considerable pre‐freeze mortality, with lethal temperature (LTemp₅₀₎ values of ?16.3 and ?21.3 °C, respectively. Lethal time experiments indicated a similar lack of cold tolerance with 50% mortality of both non‐acclimated and acclimated larvae after 7 days at ?5 °C, 10 days at 0 °C and 13 days at 5 °C. Field trials showed that neither non‐acclimated nor acclimated larvae survived longer than 1 month when exposed to naturally fluctuating winter temperatures. These results suggest that releasing E. eremicus into British greenhouses would pose minimal risk because typical British winter temperatures would be an effective barrier against establishment in the wild.     

The effect of temperature on the population growth potential of Culex annulirostris Skuse (Diptera: Culicidae)

The effect of temperature on the population growth potential of Culex annulirostris was determined by studying larval growth rate and survival at seven temperatures between 10 and 40°C, and adult survival and fecundity at 20, 25 and 30°C. All larvae died at Wand 40°C; survival was greatest at 25°C. The period for complete juvenile development ranged from 8.57 days (35°C) to 37 days (15°C). Development from egg to adult required 196 day-degrees above 9.7°C with incubation temperatures between 15 and 30°C. Population growth potential was positive at 20, 25 and 30°C, greatest at 25°C, but negative at 15°C. The minimum temperature for population growth was estimated as 17.5°C.     

First use of pheromones to detect phenology patterns and density relationships of pine sawflies in German forests

1 Monitoring studies of pine sawflies with pheromone traps were performed for the first time in Germany. Pheromone traps baited with species‐specific pheromone substances were installed in pine forests at different locations in Bavaria, Brandenburg and Lower Saxony during two years. 2 It was possible to track the flight phenology of Diprion pini, Gilpinia pallida and Neodiprion sertifer reliably and to get information about the number of generations of these species in 1997 and 1998. 3 A clear relationship between trap catch and population density could not be detected, but qualitative changes in trap catch caused by different density levels were observed. 4 For D. pini, trap catches were different among endemic populations of different forest types. Furthermore, catches of males reflected the results from the regular cocoon collections by foresters during the previous winter. 5 For N. sertifer, trap catches in endemic populations were well separated from trap catches on sites with higher sawfly densities. However, no significant correlation between trap catch and sawfly density or defoliation level could be found. These results suggest that the efficacy of the pheromone traps probably varied with biological features (sex ratio, density level, immigration) of the particular population.     

Flight activity of the damson–hop aphid, Phorodon humuli.

Flight activity of Phorodon humuli was monitored using suction traps, laboratory studies and mark and recapture experiments. Emigrants were trapped as they flew from a Myrobalan (Prunus cerasifera) hedge and among dwarf hops (Humulus lupulus). Daily flight curves were bimodal with 69% and 38% of emigrants caught in the morning peak near Myrobalan and among hops, respectively. The median period of flight activity was from 2 h after sunrise until 30 min before sunset. The lower temperature for flight was 13.5°C in the field and 14.9°C for take off in the laboratory. Variations in wind speed had little effect on flight activity explaining <2.5% of the total variance among insect counts. The percentage of emigrants on hop declined exponentially with time. The relationship, y= 10.9(±2.0) + 64.3(±2.3) × 0.92(±0.01)^t where t = daylight hours (standard error in parentheses), explained 98.3% of the variance. Hence, 62% of new arrivals flew within 1 day of arrival and 79% within 2 days. Similar numbers arrived as departed at 08:30, 10:30 and 12:30 h, but at 14:30 h twice as many arrived than departed and at 16:30 h, the accumulation was threefold. Daily flight curves of return migrants and males leaving hop were bimodal with 70% and 80%, respectively, trapped in the earlier peak. In the field, the median lower temperature for flight was 13.2°C for return migrants and a nonsignificantly different 12.8°C for males. The mean temperature for take off by return migrants was 15.7°C in the laboratory.     

Temperature effects on the development and fecundity of <Emphasis Type="Italic">Encarsia acaudaleyrodis</Emphasis> (Hymenoptera: Aphelinidae), a parasitoid of <Emphasis Type="Italic">Bemisia tabaci</Emphasis> (Homoptera: Aleyrodidae) on cucumber

Development, reproduction, and life table parameters of the parasitoid Encarsia acaudaleyrodis Hayat parasitizing Bemisia tabaci Gennadius were studied at constant temperatures in the range of 20–32°C under laboratory conditions. Egg-to-adult developmental time decreased from 20.3 days at 20°C to 9.0 days at 32°C. An average of 189.8 day-degrees was required to complete development above the lower threshold temperature (11.5°C). Juvenile survival was 84, 88, 70 and 69% at 20, 25, 30 and 32°C, respectively. Females of E. acaudaleyrodis oviposited means of 34.2, 54.6, 30.6 and 20.1 eggs at 20, 25, 30 and 32°C, respectively, and had a mean longevity of 21.1, 14.7, 10.0 and 9.1 days at the same four temperatures. The intrinsic rate of population increase (r_m) at the different temperatures ranged from 0.082 to 0.169, with the highest value recorded at 25°C. These data indicate that E. acaudaleyrodis may be better adapted to intermediate temperatures around 25°C and, therefore, could be a useful biological control agent of B. tabaci during spring and autumn when such temperatures are prevalent in Southwestern of Iran. The result could also be useful in developing a population model for E. acaudaleyrodis under field conditions.     

Effect of sex,age and morphological traits on tethered flight of Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) at different temperatures

The oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), is a pest of fruit and vegetable production that has become established in 42 countries in Africa after its first detection in 2003 in Kenya. It is likely that this rapid expansion is partly due to the reported strong capacity for flight by the pest. This study investigated the tethered flight performance of B. dorsalis over a range of constant temperatures in relation to sex and age. Tethered flight of unmated B. dorsalis aged 3, 10 and 21 days was recorded for 1 h using a computerized flight mill at temperatures of 12, 16, 20, 24, 28, 32 and 36 °C. Variations in fly morphology were observed as they aged. Body mass and wing loading increased with age, whereas wing length and wing area reduced as flies aged. Females had slightly larger wings than males but were not significantly heavier. The longest total distance flown by B. dorsalis in 1 h was 1559.58 m. Frequent short, fast flights were recorded at 12 and 36 °C, but long-distance flight was optimal between 20 and 24 °C. Young flies tended to have shorter flight bouts than older flies, which was associated with them flying shorter distances. Heavier flies with greater wing loading flew further than lighter flies. Flight distances recorded on flight mills approximated those recorded in the field, and tethered flight patterns suggest a need to factor temperature into the interpretation of trap captures.     

Encarsia formosa parasitizing the Poinsettia-strain of the cotton whitefly,Bemisia tabaci, on Poinsettia: bionomics in relation to temperature

Adult longevity, developmental time and juvenile mortality ofEncarsia formosa Gahan (Hymenoptera:Aphelinidae) parasitizing the Poinsettia-strain ofBemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) on Poinsettia (Euphorbia pulcherrima Willd.) were investigated in laboratory experiments at three temperatures: 16 °C, 22 °C and 28 °C. Furthermore, the parasitoid's preference for different larval stages of the whitefly was determined at 24.5 °C. The lifespan ofE. formosa decreased with temperature from one month at 16 °C to nine days at 28 °C. A lower temperature threshold of 11 °C for adult development was found. The development of juvenile parasitoids inB. tabaci lasted more than two months at the lowest temperature, but was only 14 days when temperature was 28 °C. The lower temperature threshold for immature development was 13.3 °C, yielding an average of 207 day-degrees for the completion of development into adults. Juvenile mortality was high, varying from about 50% at 16 °C to about 30% at 22 °C and 28 °C.E. formosa preferred to oviposit in the 4th instar and prepupal stages ofB. tabaci followed by the 2nd and 3rd instars. The preference for the pupal stage was low. The parasitoid used all instars of the whitefly for hostfeeding, with no apparent differences between the stages. The average duration of the oviposition posture was four minutes. Demographic parameters were calculated from life tables constructed from the data. The intrinsic rate of increase (r _m) and the net reproductive rate (R ₀) increased with temperature from 0.0279 day⁻¹ at 16 °C to 0.2388 day⁻¹ at 28 °C and from about 12 at 16 °C to about 66 at 28 °C, respectively.     

Specific features of distribution and size indices of four poorly studied species of sculpins (Cottidae) in the Okhotsk Sea Waters off Kamchatka

Evidence on occurrence in catches and characteristic of the spatial-bathymetric distribution and size indices of four species of Cottidae—frog sculpin Myoxocephalus stelleri, brightbelly sculpin Microcottus sellaris, antlered sculpin Enophrys diceraus, and furseal sculpin Stelgistrum stejnegeri—in summer-autumn months in the Okhotsk Sea waters off Kamchatka (site from 51°15′ to 57°20′ N, depths of 11–100 m) are provided. The first three species occur mainly in the northern part of the shelf above 54° N at depths smaller than 30–40 m within a comparatively well warmed surface water mass of seasonal modification at near-bottom temperature values above 6°C at various solid grounds. Maximum catches of S. stejnegeri were recorded only at a site of the western Kamchatka shelf from 54°00′ to 54°20′ N on pebbly-stony ground in a narrow bathy-metric range of 41–60 m on the boundary between the well warmed surface water mass of autumn modification and the cold intermediate water mass at a water temperature below 2°C. Evidence on the size-weight indices of the studied species of Cottidae in trawl catches in the Okhotsk Sea waters off Kamchatka in the study period is provided.     

Life history parameters for Nesidiocoris tenuis (Reuter) (Het., Miridae) under different temperature regimes

The development time for eggs and nymphs and female fertility were determined for Nesidiocoris tenuis Reuter (Het., Miridae: Dicyphini) at 15, 20, 25, 30, 35 and 40 ± 1°C, using tomato, Solanum esculentum (Miller), as substrate and eggs of Ephestia kuehniella Zeller as substitute prey. At 40°C, N. tenuis was unable to develop and barely reproduced. Egg development ranged from 30.8 days at 15°C to 6.3 days at 35°C. The cumulative thermal requirements for the eggs were 148.6 degree days (°d) and the lower thermal threshold, 10.3°C. The duration of the nymphal instar decreased from 55.9 days at 15°C to 8.6 days at 35°C. The thermal constant for the nymphs was 182.3 °d and the lower thermal threshold 11.7°C. No nymphs survived at 40°C, and the highest mortalities were at extreme temperatures (15 and 35°C). Female and male weights were influenced significantly by temperature. The fertility of N. tenuis females was reduced greatly at 15 and 40°C. The highest fertility during an observation period of 18 days following female emergence (79.5–60.0 nymphs per female) was within the temperature range of 20 to 35°C. Fertility was related directly to female weight and temperature (r² = 0.932). Based on development, reproduction data and thermal requirements, the optimum temperature range for N. tenuis was established as being between 20 and 30°C. Overall, N. tenuis is the most thermophilous of all dicyphines from vegetable crops in the Mediterranean area studied so far.     

湖北高海拔地区性信息素对小菜蛾的诱捕和防治效果

2002年应用性诱剂对海拔1 200 m山区甘蓝田小菜蛾的发生及防治进行了研究。在第一茬蔬菜生长期有2个诱蛾高峰,诱蛾量(头/盆)分别为11.7±2.4和9.2±1.0;第二茬蔬菜生长期有3个诱蛾高峰,诱蛾量(头/盆)分别为70.9±8.0、16.1±2.5和11.1±1.9。应用性诱剂诱捕山区甘蓝田小菜蛾时,第一茬田间蛾密度与单盆诱捕量相关性不显著,而第二茬菜生长期田间蛾密度与单盆诱蛾量相关性显著(y=0.0116x+0.1614, r=0.9213, P=0.0011)。性诱剂在光期与暗期都可诱到小菜蛾雄虫, 没有明显的诱蛾高峰。应用性诱剂可以使菜田的农药使用减少3～5次,降低田间子代幼虫密度。