Effects of contact kairomone and experience on initial giving-up time

Reproduction and longevity of the anthocorid predators Orius laevigatus (Fieber) and Orius albidipennis (Reuter) (Heteroptera: Anthocoridae) were studied under controlled conditions in the laboratory. Three different diets were tested: eggs of the Mediterranean flour moth. Ephestia kuehniella Zeller, E. kuehniella eggs plus pollen, and pollen only. Small rooted plants of Spanish pepper (Capsicum annuum L. cv. Creta, long red) served as oviposition substrate and moisture source. In all treatments, total fecundity, oviposition period and female longevity of O. laevigatus were greater than that of O. albidipennis. When a diet of E. kuehniella eggs was supplemented with pollen, total fecundity of O. albidipennis was increased by about 40%. Female O. albidipennis fed only pollen laid five times less eggs than those fed flour moth eggs and pollen; also, longevity of females was shorter when only pollen was offered as food. Fecundity and longevity of O. laevigatus were not influenced when supplementing a diet of E. kuehniella eggs with pollen. Females of O. laevigatus receiving only pollen reduced egg production by about 60% but had a similar longevity as those receiving a diet including flour moth eggs. In either species, preoviposition period and egg hatch were not affected by diet. The ability of both anthocorids to use pollen as an alternative or additional food is discussed in relation to their practical use in integrated control programmes.     

Modelling population dynamics of Orius laevigatus and O. albidipennis (Hemiptera: Anthocoridae) to optimize their use as biological control agents of Frankliniella occidentalis (Thysanoptera: Thripidae)

ORIUS LAEVIGATUS: (Fieber) and O. albidipennis (Reuter) play an important role in the control of Frankliniella occidentalis (Pergande) in crops and natural vegetation in the Mediterranean area. The biological parameters of the two anthocorids were studied and modelled in relation to temperature to optimize their use in thrips control programmes. Development times and reproductive parameters of O. laevigatus and O. albidipennis were determined at 20, 25, 30 and 35 degrees C. Pre-imaginal development times ranged from 34.6 and 37.2 days at 20 degrees C to 12.3 and 10.2 days at 35 degrees C in O. laevigatus and O. albidipennis, respectively. The lower thermal development threshold was significantly higher for O. albidipennis (14.2 +/- 0.9 degrees C) than for O. laevigatus (11.3 +/- 0.7 degrees C). No significant differences in fecundities between the two anthocorids were observed at 20, 25 and 30 degrees C. At 35 degrees C, O. albidipennis had a significantly higher fecundity than O. laevigatus. Non-linear models were used to explain reproduction and female survivorship in relation to temperature. The upper reproductive thresholds were estimated at 40.9 +/- 0.3 and 35.5 +/- 0.1 degrees C for O. albidipennis and O. laevigatus, respectively. The different optimum temperatures may explain, at least in part, the different distributions of the two species in the Palaeartic region and their population dynamics in greenhouses and natural vegetation in the south of Spain. The estimation of rm as a function of temperature showed high variability between years. Three release rates of 0.75-0.25 Orius per plant are recommended from early March to mid May to deal with thrips outbreaks in pepper crops.     

Overwintering Biology of the Predatory Bug Orius albidipennis (Hemiptera: Anthocoridae) in Israel

The predatory bug Orius albidipennis (Hemiptera: Anthocoridae) overwinters in Israel as adults. Oviposition continues irrespective of day length, but stops almost completely when the mean temperature drops below 15 C (beginning in December). During winter months, the outdoor females enter reproductive diapause, and resume oviposition in during March and April. All first instar nymphs die at low temperatures, whereas approximately 20% of the nymphs of later instars may survive and mature. Dense populations of the western flower thrips, Frankliniella occidentalis, develop outdoors in Israel about a month before the peak in population of O. albidipennis, and have the opportunity to cause much damage. Since the Israeli O. albidipennis does not enter diapause under short day photophase, it might be an efficient predator of F. occidentalis in greenhouses in countries of northern latitude.     

Diapause and survival in winter in two species of predatory bugs,Orius sauteri and O. minutus

The cause of differences in overwintering success between the sexes in Orius sauteri (Poppius) and O. minutus (Linnaeus) (Heteroptera: Anthocoridae) was investigated in the laboratory. The survival rate of adults was examined in a screen house outdoors during the winters of 1995–1996 and 1996–1997. None of the males of either species survived until spring in either year. However, 63.9% and 40.5% of the females in O. sauteri and O. minutus, respectively, survived the winter in 1995–1996, and 54.5% and 43.2%, respectively, in 1996–1997. Most of the males died by early winter. In both species, the adult females reared under short days (= L11:D13) survived for a long period at 5 or 0°C, while the males reared under the same photoperiod died shortly after transfer to 5 or 0°C from 22°C. The males and females kept at same temperature conditions under long days (= L16:D8) died early. When nymphs were kept under long days at 22°C, the lipid content in the female and male adults of O. sauteri was 27.9% and 17.7%, respectively. When nymphs were kept under short days, their lipid content was significantly higher (41.1%) than that of those reared under long days for females, but lipid content was comparable in the males regardless of photoperiod (15.6%). In O. minutus, the mean lipid content was 27.2% in females and 19.0% in males under long days at 22°C, and 40.8% in females and 19.8% in males under short days. Thus, a large amount of lipid was accumulated only in females kept under short days in both species. These results suggest that short days induced diapause only in adult females but not in males. Due to the lack of diapause and shortage of lipid accumulation, males may not be able to survive the winter.     

Influence of species of host plants on the predation of thrips by Neoseiulus cucumeris, Iphiseius degenerans and Orius laevigatus

A leaf-disc bioassay was used to compare the predation levels of two species of predatory mites (Neoseiulus cucumeris (Oudemans) and Iphiseius degenerans (Berlese)) and a predatory bug (Orius laevigatus (Fieber)), on the thrips Frankliniella occidentalis (Pergande) and Heliothrips haemorrhoidalis (Bouché), feeding on a range of susceptible plant species from twelve plant families. The predatory bug, O. laevigatus, reduced the number of thrips to a greater extent than the predatory mites and all three predators showed greater levels of predation on F. occidentalis than on H. haemorrhoidalis. The level of predation caused by each predator varied among the species of plants; the variation was greater on the plant hosts of H. haemorrhoidalis than of F. occidentalis.     

Influence of temperature on bionomics of cotton aphid, Aphis gossypii, on cotton

Life table parameters of Aphis gossypii Glover (Homoptera: Aphididae) on Gossypium hirsutum L. were determined at six temperatures (10, 15, 20, 25, 30, and 35 ± 0.5°C) in the laboratory. Relationships of life table parameters with temperature were described with mathematical equations. Development was fastest at 30°C, with a pre-larviposition period of 4.6 d. Survival to adult was greatest at 25°C (81%). Fecundity was highest at 25°C, with a total fecundity of 28.3 nymphs per female and a mean reproductive rate of 3.1 nymphs per female per day. Threshold temperatures for development in the first through fourth instar and the adult were 8.2, 8.0, 7.2, 6.2 and 7.9°C, respectively. The durations of these stages, expressed as temperature sums above these thresholds, were 24.2, 23.7, 23.0, 25.5 and 168.8 degree-days (D°), respectively. A. gossypii achieved its maximum net reproductive number (24.4 nymphs per female) and greatest intrinsic rate of increase (0.386 d–1) at 25°C. The high relative rate of population increase at 25°C results in a daily population increase of 47% and a doubling time of only 1.8 d, illustrating the tremendous growth capacity of A. gossypii populations under favourable conditions. Compared to literature sources, our source of A. gossypii, fed on cotton, showed a comparatively great heat tolerance.     

Respiratory metabolism of mosquitofish,Gambusia affinis: effects of temperature,dissolved oxygen,and sex difference

Synopsis Routine respiratory metabolic rates of mosquitofish (0.2 g live weight) were determined at 10, 15, 20, 25, 30, and 35°C at normoxic, hypoxic (= 40 torr P_O2), and extreme hypoxic (= 25 torr P_O2) conditions. Rates generally increased with increases in temperature (overall Q₁₀ = 2.11 at normoxia). Significant depressions (P<0.05) in rates were measured at 30 and 35°C at extreme hypoxic conditions. Males exhibited higher mortality at extreme hypoxia than females, especially at 35°C. Metabolic rates were significantly elevated at hyperoxic conditions (= 300 torr P_O2) at 25 and 30°C, but not at 35°C. Resting routine rates of less-confined fish were determined at 20, 25, and 30°C at normoxia and were significantly lower than the routine rates at the same temperatures. Behavioral experiments showed that aquatic surface respiration is initiated by mosquitofish at 20–65 torr P_O2 and is obligatory below 20 torr at 20° C. Overall, respiratory metabolic rates provide a quantitative metabolic basis from which predation rates of mosquitofish in various environments can be estimated.     

Effect of temperature on growth,reproduction and survival of the freshwater planorbid snail,Gyraulus convexiusculus,vector of echinostomiasis

Studies were carried out to investigate the effects of 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40° and 45°C on growth, sexual maturity, reproduction and survival of the freshwater planorbid snail, Gyraulus convexiusculus, vector of echinostomiasis, under laboratory conditions. The growth rate of juvenile and sexually mature snails was at minimum at 15°C and was maximum at 35°C. Sexual maturation time was minimum at 35°C and maximum at 20°C. Fecundity was minimum at 15°C and maximum at 35°C. The minimum average and maximum number of eggs per egg capsule was reached at 35°C and lowest at 15°C. 30°C was the optimum temperature for survival of juvenile snails, while sexually mature snails reached maximum survival time at 20°C.     

东亚小花蝽对西方花蓟马和二斑叶螨的捕食选择性

多食性天敌对猎物的捕食选择性及猎物密度对天敌捕食的干扰作用直接影响到天敌对不同猎物的控制作用.在实验室条件下研究了东亚小花蝽对西方花蓟马和/或二斑叶螨不同虫态的捕食选择性,以及两猎物中一种猎物的密度变化对小花蝽取食另一种猎物的影响.结果如下:东亚小花蝽5龄若虫和成虫对西方花蓟马2龄若虫的捕食选择性均强于对其成虫,对二斑叶螨的选择性为雌成螨>若螨>幼螨.实验中西方花蓟马2龄若虫是东亚小花蝽最喜好的虫态.二斑叶螨雌成螨密度固定为60头/19.63cm2,西方花蓟马若虫密度从10增加到60时显著地减少了东亚小花蝽对二斑叶螨的取食.反之,固定西方花蓟马同样密度,增加二斑叶螨密度却没有显著改变小花蝽对西方花蓟马的取食.此结果进一步表明,西方花蓟马是东亚小花蝽更喜好的猎物.     

Compatibility of Orius laevigatus Fieber (Hemiptera: Anthocoridae) with Neoseiulus Amblyseius cucumeris Oudemans (Acari: Phytoseiidae) and Iphiseius Amblyseius) degenerans Berlese (Acari: Phytoseiidae) in the biocontrol of Frankliniella occidentalis Pergande (Thysanoptera: Thripidae)

The compatibility of Orius laevigatus Fieber with Neoseiulus (Amblyseius) cucumeris Oudemans as predators of Frankliniella occidentalis Pergande was assessed in 24 h tests on French bean leaf discs. At varying densities of N. cucumeris and F. occidentalis in the presence of a single female O. laevigatus, it was found that O. laevigatus fed on both other organisms to a similar extent, thus raising questions as to the suitability of this combination of predators in the biocontrol of F. occidentalis. In similar trials assessing the compatibility of O. laevigatus with Iphiseius (Amblyseius) degenerans Berlese, O. laevigatus preyed on F. occidentalis to a greater extent than on I. degenerans. It is hypothesized that O. laevigatus and I. degenerans could be used simultaneously in the biocontrol of F. occidentalis with minimal interference between them.     

南方小花蝽在不同试验空间对西花蓟马的捕食及搜寻效应

【背景】南方小花蝽是一类很有利用前景的捕食性天敌,而有关其在不同捕食空间下对我国局部地区暴发成灾的重要入侵害虫西花蓟马捕食控制效能的研究较少。【方法】在实验室条件下比较研究了南方小花蝽成虫在不同试验空间对西花蓟马成虫、若虫的捕食选择性、捕食功能反应与搜寻效应。【结果】南方小花蝽成虫对西花蓟马若虫的捕食选择性强于成虫;在相同的试验空间,南方小花蝽成虫的日均捕食量随猎物数量的增加而增大,其对西花蓟马成虫和若虫的捕食量在猎物数量为每指形管中60头时最大,分别为15.90和19.30头;而搜寻效应随猎物数量的增加而降低。在各供试条件下,捕食功能反应均符合Holling Ⅱ型方程;南方小花蝽成虫在小饲养容器中对西花蓟马若虫的瞬时攻击率最大,为1.2794;而在大饲养容器中对西花蓟马成虫的瞬时攻击率最小,仅为0.3506,其处理1头西花蓟马成虫的时间约需0.0402d,而处理1头若虫的时间仅需0.0242d。在相同的猎物数量下,南方小花蝽成虫在大饲养容器中对西花蓟马的日均捕食量均低于其在小饲养容器中对西花蓟马的日均捕食量。【结论与意义】南方小花蝽对西花蓟马有很强的捕食效能,对西花蓟马的种群消长具有一定控制作用。本研究旨在为应用南方小花蝽防治西花蓟马积累资料,同时为西花蓟马的综合治理奠定理论基础。     

Plant regeneration from isolated microspores of linseed (Linum usitatissimum L.)

Embryogenesis and plant regeneration were induced in isolated microspore culture of linseed (oilflax, Linum usitatissimum). Microspores underwent cell divison which led to either microcallus or embryoid formation, when they were cultured in a modified liquid Nitsch-Lichter-Nitsch medium (Lichter 1985) at two different incubation temperatures (30 and 35 °C); some embryoids and microcalli further developed to larger calli. After transfer of the microspore derived calli to a solid medium containing zeatin (Img 1^–1) shoot induction was achieved from 36 to 66% of the calli. The highest frequency of regenerated plants was obtained in microspore cultures of the hybrid Atalante x Szegedi 62 (F₁) at 30 °C, whereas for the second genotype Pedigree 2 x Kiszombori 41 (F₂) the higher incubation temperature seemed to be more efficient. Shoots could be successfully rooted on an indole acetic acid containing medium and then transplanted to vermiculite and finally to soil. Most of the plants survived the transfer into soil in the greenhouse, where they could be successfully grown to maturity.Abbreviations BAP 6-benzylaminopurine - 2,4D dichlorophenoxyacetic acid - IAA indole acetic acid - N6 Chu (1978) medium - NAA naphthaleneacetic acid - NLN Nitsch-Lichter-Nitsch (1985) - MS Murashige and Skoog (1962) medium - ZEA zeatin     

Effect of constant temperatures on germination, radial growth and virulence of Metarhizium anisopliae to three species of African tephritid fruit flies

The effect of temperatureon conidial germination, mycelial growth, andsusceptibility of adults of three tephritidfruit flies, Ceratitis capitata(Wiedemann), C. fasciventris (Bezzi) andC. cosyra (Walker) to six isolatesof Metarhizium anisopliae were studied inthe laboratory. There were significantdifferences among the isolates in the effect oftemperature on both germination and growth.Over 80% of conidia germinated at 20, 25 and30°C, while between 26 and 67% conidiagerminated at 35°C and less than 10% at15°C within 24 hours. Radial growth was slowat 15°C and 35°C with all of theisolates. The optimum temperature forgermination and mycelial growth was 25°C. Mortality caused by the six fungal isolatesagainst the three fruit fly species varied withtemperature, isolate, and fruit fly species.Fungal isolates were more effective at 25, 30and 35°C than at 20°C. The LT₉₀values decreased with increasing temperature upto the optimum temperature of 30°C. Therewere significant differences in susceptibilitybetween fly species to fungal infection at allthe temperatures tested.     

Recovery of plants from “Near-Lethal” stress

This study reports on the dieback and recovery of red-osier dogwood, Cornus sericea L. plants from near-lethal (NL, sublethal) stress after varying lengths of post-stress environment (PSE). Intact dormant stems were subjected to 47° C for one hour during either October, November or December, and then placed into either constant 0° C or 23° C (dark condition) or kept under natural conditions at Corvallis, OR. Plants exposed to NL-heat stress in October died prior to 9 weeks of 0° C PSE, while none of the plants from other PSE treatments showed signs of injury. For plants exposed to NL-heat stress during November and December, stemdieback occurred at 0° C after 12 and 15 weeks, respectively. None of the plants from the other PSE treatments were injured. Post-stress temperatures of 0° or 5° C following NL-heat in October were lethal while temperatures above 10° C allowed recovery. Post-stress exposure to 0° C injured excised stems within 48 h, whereas irreversible damage to whole plants occurred by two weeks. Dormant plants exposed in October to other stresses, e.g., freezing temperature and hydrogen cyanamide, at NL dosages showed that these stresses also caused plant dieback at 0° C and little or no dieback at 23° C PSE.Abbreviations NL Near-Lethal - PSE Post-Stress Environment     

The effect of ambient temperature on the relationship between ventilation and metabolism in a small parrot (Agapornis roseicollis)

Summary Values for basal metabolism, standard tidal volume (V _T), standard minute volume ( ), and mean extraction efficiency (EO₂) in the thermal neutral zone (TNZ) inAgapornis roseicollis (1.84 ml·min^–1; 0.95 ml·br^–1, STPD; and 33.3 ml·min^–1, STPD; and 22.5%; respectively) were all very similar to values for these parameters previously measured inBolborhynchus lineola, a similarly sized, closely related species from a distinctly different habitat.Having both a lower critical temperature (T_lc) below and an upper critical temperature (T_uc) above those ofB. lineola, the TNZ ofA. roseicollis extended from 25° to at least 35°C. The thermal conductance below the TNZ ofA. roseicollis was 14% less than that ofB. lineola. Therefore, at 5°C the standard metabolic rate (SMR) of the former is 17% less than that of the latter, and at 35°C it is 20% less. At 5°CA. roseicollis has a lower EO₂ and at 35°C a higher EO₂ than that ofB. lineola. The patterns of resting energy metabolism and of ventilation ofA. roseicollis and ofB. lineola are consistent with the former species being better suited to living in a more variable thermal environment than the latter.MeanV _T has a weak positive correlation with the rate of oxygen consumption ( ) at a constant ambient temperature (T _a) but a much stronger correlation when resting increases in response to a decrease inT _a.V _t is the only ventilatory parameter which is linearly correlated toT _a from 35° to –25°C. The data suggest thatT _a may have a regulatory effect onV _T somewhat independent of or .     

南方小花蝽对西花蓟马和蚕豆蚜的捕食作用

南方小花蝽Orius similis是多种小型害虫的重要天敌昆虫,为了掌握其控制潜能,本文研究了南方小花蝽对西花蓟马Frankliniella occidentalis和蚕豆蚜Aphis craccivora的捕食作用。研究结果表明南方小花蝽3～5龄若虫和雌成虫对西花蓟马和蚕豆蚜的功能反应均符合HollingⅡ型方程,南方小花蝽3～5龄若虫和雌成虫对西花蓟马2龄若虫的瞬时攻击率均高于蚕豆蚜。南方小花蝽5龄若虫对蚕豆蚜的控制能力比雌成虫强,而对西花蓟马的控制能力比雌成虫差。南方小花蝽5龄若虫对西花蓟马2龄若虫和蚕豆蚜的捕食率（E）随着捕食者自身的密度（P）的增加而下降,其干扰反应方程分别为E=0.412P-1.623和E=0.416P-1.639。南方小花蝽5龄若虫对西花蓟马2龄若虫和蚕豆蚜有明显的选择性,5龄若虫喜欢取食西花蓟马2龄若虫,但前期取食的猎物对其选择性有明显的影响,更喜欢选择前期取食过的猎物。     

Effect of temperature on hatching and nest site selection in the Green lynx spider, Peucetia viridans (Araneae:Oxyopidae)

1.

Thirty-seven Peucetia viridans egg sacs were incubated at 15, 17.5, 20, 25, 30, 32.5 or 35 °C. Hatching time was inversely proportional to temperature, and no hatching occurred at the extremes (15, 17.5 and 35 °C).     

Life history of the agromyzid fly Liriomyza trifolii on tomato at different temperatures

The effects of three constant (15°C, 20°C and 25°C) and one alternating (16–22°C, mean 19.5°C) temperatures on development, mortality, feeding, fecundity and longevity of Liriomyza trifolii (Burgess) on tomato plants cv. Moneydor were examined in the laboratory. Development rates and thresholds for each instar were estimated by means of linear regression. No correlation was found between life history variables and pupal length. Further, data on the biology of L. trifolii are given and discussed.The intrinsic rate of increase, r_m, varied from-0.0023 viable female eggs//day at 15°C to 0.1254 eggs//day at 25°C and net reproduction from one viable female egg/ at 15°C to 26 eggs/ at 20°C. Generation time varied from 48 days at 15°C to 24 days at 25°C. Ninety % oviposition occurred within the first 115 degree-days of adult life at both 20°C and 25°C. Fecundity and longevity were highly correlated with the number of feeding punctures. The data indicate that tomato is a suitable host plant allowing populations of L. trifolii to increase if temperatures are above 16°C.

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Influence de la température sur la biologie de Liriomyza trifolii élevé sur tomates

Résumé La vitesse de développement, la mortalité, l'alimentation, la fécondité et la longévité de L. trifolii (Burgess) élevés sur plants de tomates du cultivar Moneydor ont été examinées au laboratoire sous 3 températures constantes (15°C, 20°C et 25°C) et une thermopériode (16/22°C, moyenne 19,5°C). Les taux de développement et les seuils de chaque stade ont été déterminés à partir des droites de régressions. Aucune corrélation n'a été mise en évidence entre ces variables biologiques et la taille des pupes. De plus, certaines données sur la biologie de L. trifolii sont fournies et discutées.Le taux intrinsèque d'accroissement, r_m a varié de-0,0023 oeuf viable/femelle/jour à 15°C à 0,1254 oeuf viable/femelle/jour à 25°C et la reproduction nette de 1 oeuf femelle viable/femelle à 15°C à 26 oeufs femelles viables/femelle à 25°C. La durée d'une génération a varié de 48 jours à 15°C à 24 j à 25°C. 90% de la ponte a eu lieu dans les 115 premiers degrés jours de la vie imaginale à 20 et 25°C. La fécondité et la longévité étaient fortement liées au nombre de piqûres nutritionnelles. Ces résultats montrent que la tomate est un hôte convenable permettant aux populations de L. trifolii de se développer lorsque la température est supérieure à 16°C.

     

Optimization of cryopreservation of Artemisia annua L. callus

Cryopreservation of callus tissue of Artimisia annua L. was optimized. Two lines of calli were precultured on MS medium with 5% (v/v) dimethyl sulfoxide, and protected by a cryoprotectant containing 15% (v/v) ethylene glycol, 15% (v/v) dimethyl sulfoxide, 30% (v/v) glycerol and 13.6% (w/v) sucrose. The highest survival rate of callus A201 reached 87% after it was pretreated at 25°C, cryopreserved by liquid nitrogen, recovered in water bath at 25°C and reloaded at 25°C with 34% (w/v) sucrose solution, and that of callus A202 reached 78% after it was treated as callus A201, except pretreated at 35°C, recovered at 35°C and reloaded with 47.8% (w/v) sucrose solution.     

Timing of diapause induction outside the natural distribution range of a species: an outdoor experiment with the bean bug Riptortus clavatus

The phytophagous bug Riptortus clavatus (Thunberg) (Heteroptera: Alydidae) produces two or three generations per year in Central Japan and overwinters in the adult stage. In bugs from the Kyoto population (35°00 N, 135°45 E), we studied (1) the effects of day-length on the nymphal and preoviposition periods under constant photoperiod at 20.5 °C, and (2) photoperiodic induction of adult diapause at 20.5 °C and under a combination of constant photoperiod and natural daily rhythm of temperature in the forest-steppe zone of Russia (50°38 N, 35°58 E). Then, we examined (3) the timing of diapause induction under quasi-natural conditions in the same region, far outside the species' natural geographical range. At 20.5 °C, the nymphal period in both males and females was significantly longer under regimes with shorter photophases than under those with longer photophases. The preoviposition period in females was significantly longer under the near-critical long-day regime L14:D10 than under typical long-day regimes (L15:D9, L16:D8, and L17:D7). The critical day-length for diapause induction was shorter under conditions of natural daily rhythm of temperature than those reported at constant 20, 25, and 30 °C. Under quasi-natural conditions in the forest-steppe zone, R. clavatus entered diapause in September, much later than the local populations of true bugs studied to date. This experiment showed that R. clavatus was maladapted to new environmental conditions: diapause was induced too late with the result that all or most nymphs hatched in late August or early September will die.