Life tables and predation activity of Orius laevigatus and O. albidipennis at three constant temperatures

Effects of three constant temperatures (15, 25, and 35 -C) on development and reproduction of Orius laevigatus (Fieber) and O. albidipennis (Reuter) (Heteroptera: Anthocoridae) and on their predation activity against the western flower thrips Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) were investigated in the laboratory. Small rooted plants of Spanish pepper (Capsicum annuum L. cv. Creta, long red) served as oviposition substrate and moisture source. Survival of eggs and nymphs of both species was high at 25 and 35 °C. At 15 °C, none of the eggs of O. albidipennis hatched and the number of nymphs completing the immature stage was extremely low. Developmental time of nymphs was not significantly different between species at 15 °C, but at 25 and 35 °C nymphs of O. laevigatus took significantly longer to develop than those of O. albidipennis. Females of O. albidipennis lived longer than those of O. laevigatus at 15 and 35 °C, but no differences were observed at 25 °C. Fecundity of O. albidipennis was greatly reduced at 15 °C, whereas a temperature of 35 °C was close to the upper reproduction threshold of O. laevigatus. Fecundity was highest at 25 °C for both species. At 15 °C, the intrinsic rate of increase (r_m) reached a minimum for both species. For O. albidipennis, the r_m-value increased with temperature (0.121 at 25 °C and 0.202 at 35 °C), whereas for O. laevigatus it peaked at 25 °C (0.105) but decreased at 35 °C (0.051). At 15 and 25 °C, adults of O. laevigatus consumed more F. occidentalis adults during their total lifespan than those of O. albidipennis, but the latter showed a better predation activity at 35 °C; in all treatments, however, adults of O. laevigatus consumed more prey per day than did those of O. albidipennis. The performance of both anthocorids at the different temperatures is discussed in relation to their practical use in integrated pest control programmes.     

Nutritional value of brine shrimp cysts as a factitious food for Orius laevigatus (Heteroptera: Anthocoridae)

Decapsulated cysts of the brine shrimp Artemia franciscana were assessed as a factitious food for rearing the anthocorid predator Orius laevigatus. Developmental and reproductive traits of O. laevigatus reared for a single generation on A. franciscana from three geographical locations or on gamma-irradiated eggs of the Mediterranean flour moth Ephestia kuehniella were compared. There was no effect of diet on nymphal survival but nymphal period on E. kuehniella eggs (12.2 days) was 0.7-1.6 days shorter than on the Artemia diets. The predator developed 0.5-1 day faster on cysts from San Francisco Bay (USA) than on cysts from Great Salt Lake (USA) or Macau (Brazil). Fecundity on brine shrimp cysts from different locations was similar to that on flour moth eggs (142-187 eggs/female). The biochemical composition of decapsulated cysts from San Francisco Bay was compared with that of E. kuehniella eggs. Depending on the type of analysis, Artemia cysts contained higher or similar amounts of protein as compared with E. kuehniella eggs, but amino acid patterns were generally similar. Flour moth eggs were almost three times richer in fatty acids than brine shrimp cysts, with some marked differences in fatty acid profiles. Because nutrient imbalances in a diet may be expressed only after several generations of rearing, the predator was cultured for three consecutive generations on A. franciscana cysts from San Francisco Bay. In the third generation on brine shrimp cysts, nymphs took 18% longer to develop, and adults were shorted-lived and about 60% less fecund than those maintained on E. kuehniella eggs. Brine shrimp cysts may be used as a supplement in the mass production of O. laevigatus but may not be a suitable food for long-term culturing of the predator.     

The influence of pollen on combining predators to control Frankliniella occidentalis in ornamental chrysanthemum crops

Small scale glasshouse trials showed that second instar nymphs of Orius laevigatus reduced Frankliniella occidentalis numbers (78-92%) more than Neoseiulus cucumeris (0-30%). Combining the predators did not increase reduction of thrips numbers (84-93%). Pollen did not increase thrips control, but led to an increase in the number of thrips.     

Side-effects of pesticides on the predatory bug Orius laevigatus (Heteroptera: Anthocoridae) in the laboratory

Laboratory trials were carried out in order to test the effects of 29 pesticides on the predatory bug, Orius laevigatus. To evaluate residual contact activity, newly moulted fourth instar nymphs of O. laevigatus were placed on treated Petri dishes and their mortality was checked after 7 days. The fecundity of surviving females was tested for 14 days. Young O. laevigatus adults were fed with eggs of Ephestia kuehniella, treated with the (above-mentioned) pesticides, to assess the effect of pesticides by ingestion. Adult mortality, female fecundity and egg hatching were recorded. Azadirachtin, granulosis virus products, mineral oil, pirimicarb, tebufenozide, clofentezine, hexythiazox and copper oxychloride had no significant effect on the survival and fecundity of O. laevigatus when predators were exposed to pesticide residues by contact or by ingestion. Triflumuron and diflubenzuron appeared to be harmless by contact, but diflubenzuron was slightly toxic when ingested. Buprofezin and teflubenzuron were slightly to moderately toxic, while hexaflumuron, flufenoxuron, and lufenuron showed a marked toxicity by contact as well as by ingestion. A number of organophosphates, endosulfan and deltamethrin were detrimental especially by contact. Imidacloprid was very toxic by contact but only slightly toxic when ingested. Indoxacarb and methoxyfenozide were less toxic than imidacloprid. These findings should be considered when releases of O. laevigatus are used in greenhouses or on outdoor crops.     

Influence of host plant and prey availability on developmental time and surviorship of Nesidiocoris tenius (Het.: Miridae)

Nesidiocoris tenuis is a zoophytophagous mirid with biological control potential. However, the relative importance of predation and herbivory for survival and development has not been clear. The bugs survived longer on tomato than on eggplant and especially sweet pepper, but could not complete development in the absence of supplemental food. Tomato also proved to be a more favorable substrate than pepper when eggs of Ephestia kuehniella were added as a food supplement. These results demonstrated that animal prey is a required dietary component for N. tenuis, and also that survival time on a strict plant diet is host plant dependent.     

Effectiveness of Orius laevigatus (Hem.: Anthocoridae) for the control of Frankliniella occidentalis on cucumber and pepper in the UK

Biological control of Western Flower Thrips was sought by the use of Orius laevigatus, an anthocorid bug indigenous to the UK. Rearing methods were successfully devised for this species and glasshouse trials on cucumbers and peppers were conducted. It was not possible to obtain full establishment of O. laevigatus on a cucumber crop, but breeding populations established satisfactorily in the flowers of sweet peppers. On peppers, releases totalling one to two Orius per plant resulted in good thrips control over several months providing that initial thrips numbers were low. Early season supplementary lighting using tungsten bulbs to extend the photoperiod ensured good control of thrips on peppers in February and March by promoting Orius breeding on the crop.     

Functional response of Macrolophus pygmaeus (Rambur) and Nesidiocoris tenuis (Reuter) feeding on two different prey species

Functional response type and predatory parameters of Macrolophus pygmaeus and Nesidiocoris tenuis (Hemiptera: Miridae), the two important predators widely used in IPM programmes at tomato greenhouses, were investigated. The predators fed on Tuta absoluta (Lepidoptera: Gelechiidae) or Ephestia kuehniella (Lepidoptera: Pyralidae) eggs. Different densities of prey eggs including 1, 2, 3, 4, 5, 8, 10, 15, 20, 30 and 40 (latest only for E. kuehniella) were used at laboratory conditions. The results showed that both predatory bugs had type II functional response. Also, predation indices were significantly different between the predators. Although N. tenuis was more efficient against T. absoluta eggs than M. pygmaeus, M. pygmaeus predatory indices showed that this predator was more efficient on E. kuehniella eggs. Thus, minimum and maximum attack rate were observed in N. tenuis fed on E. kuehniella (0.0871 h^?1) and T. absoluta (0.2514 h^?1) eggs, respectively. Whilst, the minimum and maximum handling time were observed in M. pygmaeus fed on E. kuehniella (1.8695 h) and T. absoluta (2.7415 h) eggs, respectively.     

The impact of temperature on activity and consumption rate of moth eggs by Blattisocius tarsalis (Acari: Ascidae)

The activity of adult female Blattisocius tarsalis was investigated at temperatures of 7–13°C. At 7°C only 33% of the mites walked and these individuals all walked less than 1.5 cm min–1. All mites walked at 9°C and at 12°C all were highly active, walking more than 1.5 cm min–1. Daily food consumption rates of adult female B. tarsalis offered young eggs of Ephestia kuehniella as food were investigated at temperatures of 9–27°C. Food consumption below 13°C was very low. At temperatures of 13–19°C the mean number of fully ingested eggs had a level of between 0.5 and 1.0 egg in 24 h. At temperatures of 21–27°C the mean number of fully ingested eggs was above 1.0 egg in 24 h. The mean number of destroyed eggs per female at temperatures above 13°C ranged from three to five eggs per day. © Rapid Science Ltd. 1998     

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.     

Terminal speed and size sorting of insect eggs

Engineering data for improving the design of applicators for beneficial insect's eggs and facilitating egg cleaning at mass-rearing plants are presented. A vertical air column was developed to measure terminal speed of beneficial insect eggs. Raw material was sorted into fractions according to terminal speed and photos were taken for measuring dimensions of particles. Particle distribution was evaluated for two beneficial insect eggs used in biological control (Chrysoperla rufilabris and Ephestia kuehniella eggs parasitized by Trichogramma brassicae) and for one unparasitized host eggs (E. kuehniella). Density measurements were performed as these data were required for calculating terminal speeds using the theory of free falling bodies. Unparasitized E. kuehniella and C. rufilabris eggs stored at 5°C showed constant terminal speed (1.9 and 1.34 m/s, respectively) and density (1.05 g/cm³, for both). Terminal speed of parasitized E. kuehniella eggs decreased from 1.32 to 1.06 m/s with increasing storage time (4-8 days). Photos of subsamples suggested that aerodynamic cleaning could be used for improving the quality of raw eggs. Density evaluations showed that parasitized eggs can be separated by flotation in water. Calculated terminal speeds were accurate for unparasitized eggs but were 10-20% overestimated for parasitized eggs.     

Effect of different lighting conditions on circadian developmental rhythms and behaviour in Ephestia kuehniella Zell

Abstract

A study was made on the developmental rhythms of Ephestia kuehniella during different photoperiods: constant lighting (L/L), under conditions of 12 hours light per day (L/D) and in constant darkness (D/D). Observations were made every 2 hrs, for 3 successive 24‐hr periods, of the number of wandering larvae emerging from food, the number of pupations and of imaginai moults. Emergence of wandering larvae is rhythmic only under L/D conditions, and in addition this is also affected by the density of the larvae. Rhythm is least apparent with greatest density of the larvae. Pupation in E. kuehniella is a non‐rhythmic process with each of the photoperiods examined, whereas the imaginai moult is characterized by an endogenous (existing under D/D conditions) rhythm. Emergence of imagines is non‐rhythmic under L/L, and also when pupae under L/D fail to receive the final period of darkness. The rhythm of the imaginai moult is possibly controlled by the biological clock, which stops under conditions of constant light.     

Effect of different diets on reproduction,longevity and predation capacity of Orius insidiosus (Say) (Hemiptera: Anthocoridae)

Orius insidiosus is a generalist predator for which diet influences important biological traits like reproduction and predation. We tested the effects of different diets alone or in combination on reproduction, longevity and predation capacity of this predator. The diets tested were: no food (control); pollen; Frankliniella occidentalis (Pergande) nymphs and adults; F. occidentalis nymphs and adults and pollen; Anagasta kuehniella (Zeller) eggs; A. kuehniella eggs and pollen; A. kuehniella eggs; F. occidentalis nymphs and adults and A. kuehniella eggs, F. occidentalis nymphs and adults and pollen. The pre-oviposition period was shortest when the diet consisted of pollen and prey (A. kuehniella and/or F. occidentalis), of the two prey species together or of only A. kuehniella eggs. The highest values for the length of the oviposition period (50.1, 48.0, 46.3 and 46.1 days), daily fecundity (3.8, 3.9, 4.0 and 4.2 eggs/female/day), total fecundity (190.3, 187.7 185.2 and 193.6 eggs/female) and longevity (52.1, 49.9, 48.7 and 48.0 days) were found with diets consisting of only A. kuehniella eggs. Pollen did not improve any of the performance parameters of the predator when offered exclusively or as a complementary food. The results show that selection of a proper diet can strongly improve reproduction, longevity and predation capacity of O. insidiosus. An important finding is that A. kuehniella eggs, which can easily be produced in large quantities, are an excellent factitious prey for mass production of O. insidiosus.     

温度对微小花蝽生长发育和繁殖的影响

【目的】明确温度对微小花蝽Orius minutus生长发育和繁殖的影响。【方法】本研究以腐食酪螨Tyrophagus putresceniae为猎物,分别在5个恒温(15,20,25,30和35℃)条件下室内饲养,调查了温度对微小花蝽各虫态发育历期、存活率、成虫繁殖力以及种群参数的影响。【结果】在15~35℃范围内,各虫态平均发育历期均随温度升高而缩短,15℃下完成一个世代发育需要52.45 d,而35℃下仅需14.85 d。直线回归分析表明,微小花蝽世代发育起点温度为8.89℃,有效积温为359.20日·度。世代存活率和单雌平均产卵量均在25℃时最高,分别为17.07%和41.00粒。种群趋势指数在15℃和35℃下小于1,种群呈负增长;20~30℃下大于1,且25℃时最高,为3.92。净增殖率、内禀增长率和周限增长率均在25℃时最高,分别为3.32,0.04和1.04;种群世代周期以15℃时最长,为57.76 d,35℃时最短,为17.50 d。【结论】取食腐食酪螨的微小花蝽发育适宜温度范围为25~35℃,存活、繁殖和种群增长的最适温度均为25℃。这些结果为利用腐食酪螨人工饲养微小花蝽提供了基础参考数据。     

Ultrastructure of distal flagellar swellings in spermatocytes and spermatids of Ephestia kuehniella Z. (Pyralidae,Lepidoptera)

Summary Development of flagella was investigated by transmission electron microscopy in spermatocytes and spermatids of the Mediterranean mealmoth, Ephestia kuehniella Z. Growing flagella displayed voluminous distal swellings. In short flagella the apical portion of the swellings contained an amorphous, dense accumulation. In more developed flagella a less dense proximal extension of the apical accumulation was formed, which in turn was in contact with the elongating flagellar microtubules. The material of the flagellar tip is interpreted as being a precursor of the axoneme containing mainly tubulin. The material may be converted into the axoneme.     

Induction and termination of diapause inOrius predatory bugs

Photoperiodic induction of reproductive diapause at 18°C was investigated in fourOrius [Heteroptera: Anthocoridae] species.Orius insidiosus (Say) displayed a long-day response with a critical photoperiod between L11:D13 and L12:D12. Diapause in this species was terminated rapidly when the temperature and/or the daylength were increased.Orius majusculus (Reuter) also displayed a long-day response. The critical photoperiod fell between L14:D10 and L16:D8. Diapause in this species was not terminated within 14 days when both temperature and daylength were increased. InOrius albidipennis (Reuter) no diapause could be induced at photoperiods varying from L8:D16 to L16:D8. InOrius tristicolor (White) a high proportion of diapause was found at all photoperiods tested. The effect of temperature on photoperiodic induction of diapause was studied inO. insidiosus at L10:D14. Diapause occurred at 18°C, 21°C and 25°C, but not at 30°C. Again, diapause was terminated rapidly after transfer to 25°C/L16:D8. Exposing only the nymphal instars 1–5 to short daylength was not enough to induce diapause in the whole population ofO. majusculus. Orius predatory bugs are used as biocontrol agents against western flower thrips,Frankliniella occidentalis (Pergande) [Thysanoptera: Thripidael, in greenhouses. The consequences of photoperiodic induction of diapause for the success of early season releases ofOrius are discussed.     

Effects of altered stride frequency and contact time on leg-spring behavior in human running

Many studies have demonstrated that contact time is a key factor affecting both the energetics and mechanics of running. The purpose of the present study was to further explore the relationships between contact time (t(c)), step frequency (f) and leg stiffness (k(leg)) in human running. Since f is a compound parameter, depending on both contact and aerial time, the specific goal of this study was to independently vary f and t(c) and to investigate their respective effects on spring-mass characteristics during running, seeking to determine if the changes in k(leg) observed when running at different f are mainly due to inherent changes in t(c). We compared three types of constant 3.33 m s(-1) running conditions in 10 male subjects: normal running at the subject's freely chosen f, running with decreased and increased f, and decreased and increased t(c) at the imposed freely chosen f. The data from the varied f trials showed that the variation of t(c) was strongly correlated to that of k(leg) (r(2)=0.90), and the variation of f was also significantly correlated to that of k(leg) (r(2)=0.47). Further, changes in t(c) obtained in various t(c) conditions were significantly correlated to changes in k(leg) (r(2)=0.96). These results confirm that leg stiffness was significantly influenced by step frequency variations during constant speed running, as earlier demonstrated, but our more novel finding is that compared to step frequency, the effect of contact time variations appears to be a stronger and more direct determinant of k(leg). Indeed, 90-96% of the variance in k(leg) can be explained by contact time, whether this latter parameter is directly controlled, or indirectly controlled through its close relationship with step frequency. In conclusion, from the comparison of two experimental procedures, i.e. imposing various step frequency conditions vs. asking subjects to intentionally vary contact time at their freely chosen step frequency, it appears that changes in leg stiffness are mainly related to changes in contact time, rather than to those in step frequency. Step frequency appears to be an indirect factor influencing leg stiffness, through its effect on contact time, which could be considered a major determinant of this spring-mass characteristic of human running.     

Effects of sibling-rearing experience on future reproductive success in two species of callitrichidae

The survival rate for offspring of mothers who either had or did not have previous experience rearing younger siblings was compared in two callitrichid species, Callithrix jacchus and Saguinus oedipus. Offspring of mothers with sibling-rearing experience had a higher survival percentage than offspring of inexperienced mothers in both species. While 50–60% of offspring of inexperienced C. jacchus mothers survived, no offspring of inexperienced S. oedipus mothers survived. The results suggest that sibling-rearing experience is necessary for adequate maternal behavior in S. oedipus, but not necessary to the development of maternal behavior in C. jacchus. Effects of previous sibling-rearing experience of S. oedipus fathers on offspring survival were also examined. Whether the father had rearing experience was not related to the survival of their offspring.     

Effects of external carbon source and empty bed contact time on simultaneous heterotrophic and sulfur-utilizing autotrophic denitrification

The effects of external carbon source (both type and concentration) and empty bed contact time (EBCT) on denitrification efficiency during simultaneous heterotrophic and sulfur-utilizing autotrophic denitrification were evaluated. Continuous experiments were conducted with up-flow mode sulfur packed bed reactors (SPBRs) fed with nitrified leachate containing 700–900 mg/l NO₃⁻–N. The fraction of NO₃⁻–N removed by heterotrophic denitrification (HDNR_fraction) for alkalinity production to balance the alkalinity consumption by autotrophic denitrification varied with the type of external carbon source. When methanol or sodium acetate was added at HDNR_fraction values of 60 and 44%, respectively, 100% denitrification was achieved without alkalinity addition. However, glucose required a HDNR_fraction value of 70% for complete denitrification and denitrification was not complete when molasses was used at a HDNR_fraction value of 70%. The EBCT and volumetric loading rate at which 100% denitrification efficiency could be achieved were 6.76 h and 2.84 kg NO₃⁻–N/m³ day, respectively. The maximum nitrogen removal rate was 5.05 kg NO₃⁻–N/m³ day observed with 89% removal efficiency. At short HRT, a clogging problem was observed near the bottom of the SPBR with excess growth of heterotrophic denitrifiers and gas accumulation within the pores of the SPBR. This problem may be eliminated by back-washing or by separating heterotrophic denitrification from sulfur-utilizing denitrification.     

Effects of shift in flowering time on the reproductive output of Xanthium canadense in a seasonal environment

We studied the effects of a change in flowering date on the reproductive output of a short-day annual plant, Xanthium canadense. The flowering date was changed by photoperiodic manipulation to 1 month earlier or later than the natural flowering date. Plants with the natural flowering date attained the highest reproductive output. For those flowering 1 month earlier or later, the reproductive output was decreased by 42% or 23%, respectively. The reproductive output was analyzed as the product of the biomass production during the reproductive period and its allocation to the reproductive organs. Although delay in flowering increased biomass production, it decreased its fractional allocation to the reproductive organs. The highest reproductive output in the natural flowering plants resulted from a compromise between these two effects of flowering. Plants flowering earlier had higher translocation rates to the reproductive organs and accelerated plant senescence. Later flowering caused a reduction in biomass translocation to the reproductive organs and thus extended the reproductive period. These experimental results are discussed in relation to the cost of reproduction and the optimal time for flowering that maximizes the final reproductive output. It is suggested that the natural flowering time maximized the reproductive output while minimizing the cost of reproduction. Received: 11 September 1997 / Accepted: 12 December 1997