Molecular basis for the maximum growth temperature of an obligately psychrophilic yeast, Leucosporidium stokesii.

Cells of the obligately psychrophilic yeast Leucosporidium stokesii were subjected to permissive (15 and 20 degrees C) and restrictive (23 and 25 degrees C) temperatures to determine the event(s) responsible for the low maximum growth temperature of this organism. An investigation of subcellular morphology by nuclear staining revealed that buds formed at 20 degrees C were anucleate but showed nuclear migration within the parent cell. Cells incubated initially at 23 degrees C and then shifted down to a permissive growth temperature of 15 degrees C in the presence of a deoxyribonucleic acid (DNA) synthesis inhibitor, hydroxyurea, confirmed the observation that the anucleate condition of atypical buds was the result of temperature-sensitive DNA synthesis. Concomitantly, the incorporation of labeled adenine into DNA was inhibited at 23 and 25 degrees C. The synthesis of ribonucleic acid, however, was enhanced at 23 degrees C but impaired at 25 degres C. Similarly, protein synthesis was unaffected at either restrictive temperature.     

Temperature during the day, but not during the night, controls flowering of Phalaenopsis orchids

Phalaenopsis orchids are among the most valuable potted flowering crops commercially produced throughout the world because of their long flower life and ease of crop scheduling to meet specific market dates. During commercial production, Phalaenopsis are usually grown at an air temperature > or =28 degrees C to inhibit flower initiation, and a cooler night than day temperature regimen (e.g. 25/20 degrees C day/night) is used to induce flowering. However, the specific effect of day and night temperature on flower initiation has not been well described, and the reported requirement for a diurnal temperature fluctuation to elicit flowering is unclear. Two Phalaenopsis clones were grown in glass greenhouse compartments with constant temperature set points of 14, 17, 20, 23, 26, or 29 degrees C and fluctuating day/night (12 h/12 h) temperatures of 20/14, 23/17, 26/14, 26/20, 29/17, or 29/23 degrees C. The photoperiod was 12 h, and the maximum irradiance was controlled to < or =150 micromol m(-2) s(-1). After 20 weeks, > or =80% of plants of both clones had a visible inflorescence when grown at constant 14, 17, 20, or 23 degrees C and at fluctuating day/night temperatures of 20/14 degrees C or 23/17 degrees C. None of the plants were reproductive within 20 weeks when grown at a constant 29 degrees C or at 29/17 degrees C or 29/23 degrees C day/night temperature regimens. The number of inflorescences per plant and the number of flower buds on the first inflorescence were greatest when the average daily temperature was 14 degrees C or 17 degrees C. These results indicate that a day/night fluctuation in temperature is not required for inflorescence initiation in these two Phalaenopsis clones. Furthermore, the inhibition of flowering when the day temperature was 29 degrees C and the night temperature was 17 degrees C or 23 degrees C suggests that a warm day temperature inhibits flower initiation in Phalaenopsis.     

温度和食用藻密度对发头裸腹潘种群动态和两性生殖的影响

研究了不同温度和食用藻密度对发头裸腹潘种群动态和两性生殖的影响.结果表明:温度、食用藻密度对发头裸腹溞的种群密度、雄体密度和卵鞍数均有显著影响.高食用藻密度组的发头裸腹潘种群密度明显高于中、低食用藻密度组,其最大种群密度出现在20℃下的高食用藻密度组.在相同的温度下,发头裸腹溞的首次产幼溞数随食用藻密度的降低而减少,平均每个母潘首次产出的最大幼潘数出现在25℃下的高食用藻密度组.高食用藻密度组发头裸腹潘产生的雄体密度明显高于中、低食用藻密度组.发头裸腹溞的雄体密度与其种群密度之间存在极显著的相关性.发头裸腹溞所产的卵鞍数随食用藻密度的下降而下降,且25℃下发头裸腹溞所产的卵鞍数明显高于其他温度组.与温度相比,食用藻密度对发头裸腹潘的种群动态和两性生殖的影响更大.     

Development, survivorship, and reproduction of Helicoverpa armigera (Lepidoptera: Noctuidae) under constant and alternating temperatures

Laboratory studies were conducted to assess the effect of temperature on the survival, development, fecundity, and longevity of Helicoverpa armigera (Hübner) at 11 constant temperatures ranging from 12.5 to 40 degrees C, as well as at five alternating temperature regimes (25-10, 30-15, 32.5-17.5, 35-20, and 35-27.5 degrees C) and under a photoperiod of 16:8 (L:D) h. H. armigera reared at constant temperatures did not develop from egg to adult (emergence) outside the temperature range of 17.5-32.5 degrees C. The alternating conditions expanded this range from 10 to 35 degrees C. The lowest developmental thresholds of the immature stages were estimated by a linear model and ranged from 10.17 (pupal stage) to 11.95 degrees C (egg stage) at constant temperature regimes and from 1.1 to 5.5 degrees C, respectively at alternating temperatures. The values of developmental thresholds estimated using the nonlinear (Lactin-2) model were lower than those estimated by the linear model for constant and alternating temperature regimes except for larval and pupal stages at constant temperatures. Mean adult longevity fluctuated from 34.4 d at 15 degrees C to 7.6 d at 35 degrees C. Females reared under all alternating temperature regimes laid more eggs than females reared at any, except the 25 degrees C, constant temperature treatment. The intrinsic rate of increase was highest at 27.5 degrees C, at both the constant and the corresponding alternating temperature regimes (0.147 and 0.139, respectively). Extreme temperatures had a negative effect on life table parameters.     

Low temperature stress-induced biochemical changes affect stubble bud sprouting in sugarcane (<Emphasis Type="Italic">Saccharum</Emphasis> spp. hybrid)

A laboratory experiment was conducted to study the effect of low temperature stress on stubble bud sprouting and associated biochemical changes in sugarcane (Saccharum spp. hybrid). At 25°C, stubble bud sprouting was about 80%, whereas at 15 and 6°C, it was 56% and 23%, respectively. In stubble buds, the levels of reducing sugars and acid invertase were low, while IAA, total phenols and proline contents were high at low temperatures, as compared to normal temperature (25°C). Similarly, the specific activities of antioxidant enzymes, viz., catalase and peroxidase in stubble buds were higher at low temperatures than at normal temperature. The results indicate that poor sprouting of stubble buds at low temperatures appears to be due to a reduced availability of reducing sugars concomitant with a lower activity of acid invertase. An increased level of IAA together with toxicity build-up in situ due to an accumulation of total phenols may be responsible for the maintenance of dormancy in stubble buds at low temperatures. On the other hand, higher activities of catalase and peroxidase enzymes may protect stubble buds from an oxidative damage, while proline accumulates to act as an osmoprotectant under low temperature stress.     

The immune response of tilapia Oreochromis mossambicus and its susceptibility to Streptococcus iniae under stress in low and high temperatures

Mozambique tilapia Oreochromis mossambicus acclimated to 27 degrees C were then held at 19, 23, 27 (control), 31 and 35 degrees C, and were examined for non-specific cellular and humoral responses after 12-96 h. Total leucocyte count decreased significantly when fish were transferred to 19 and 23 degrees C after 48 and 96 h, and when transferred to 35 degrees C over 12-96 h, respectively. Respiratory burst decreased significantly when fish were transferred to 19, 31 and 35 degrees C over 24-96 h, whereas phagocytic activity and phagocytic index decreased significantly when fish were transferred to low temperatures (19 and 23 degrees C) and high temperatures (31 and 35 degrees C) over 12-96 h. Lysozyme activity decreased significantly when fish were transferred to 19 degrees C after 12-96 h, but increased significantly when transferred to 31 and 35 degrees C over 48-96 h. Alternative complement pathway (ACH(50)) also decreased significantly when transferred to 19 and 23 degrees C after 12h, but increased significantly when transferred to 31 and 35 degrees C after 24h. In another experiment, tilapia reared at 27 degrees C were injected intraperitoneally with Streptococcus iniae at a dose of 1 x 10(7)colony-forming units (cfu)fish(-1), and then reared onward at water temperatures of 19, 23, 27 (control), 31 and 35 degrees C. Over 48-168 h, the cumulative mortality of S. iniae-injected fish held in 19 and 35 degrees C was significantly higher than that of injected-fish held in 23, 27 and 31 degrees C. It is concluded that transfer of tilapia O. mossambicus from 27 degrees C to low temperatures (19 and 23 degrees C) after 12h, and transfer of fish from 27 degrees C to high temperatures (31 and 35 degrees C) reduced their immune capability. Moreover, tilapia under temperature stress at 19 and 35 degrees C from 27 degrees C decreased its resistance against S. iniae.     

Temperature-specific inhibition of human red cell Na+/K+ ATPase by 2,450-MHz microwave radiation

The ATPase activity in human red blood cell membranes was investigated in vitro as a function of temperature and exposure to 2,450-MHz continuous wave microwave radiation to confirm and extend a report of Na+ transport inhibition under certain conditions of temperature and exposure. Assays were conducted spectrophotometrically during microwave exposure with a custom-made spectrophotometer-waveguide apparatus. Temperature profiles of total ATPase and Ca+2 ATPase (ouabain-inhibited) activity between 17 and 31 degrees C were graphed as an Arrhenius plot. Each data set was fitted to two straight lines which intersect between 23 and 24 degrees C. The difference between the total and Ca+2 ATPase activities, which represented the Na+/K+ ATPase activity, was also plotted and treated similarly to yield an intersection near 25 degrees C. Exposure of membrane suspensions to electromagnetic radiation, at a dose rate of 6 W/kg and at five temperatures between 23 and 27 degrees C, resulted in an activity change only for the Na+/K+ ATPase at 25 degrees C. The activity decreased by approximately 35% compared to sham-irradiated samples. A possible explanation for the unusual temperature/microwave interaction is proposed.     

Temperature preference and respiration of acaridid mites

The thermal preferences in a grain mass and respiration at various temperatures in mites (Acari: Acarididae) of medical and economical importance [Acarus siro (L. 1758), Dermatophagoides farinae Hughes 1961, Lepidoglyphus destructor (Schrank 1871), and Tyrophagus putrescentiae (Schrank 1781)] were studied under laboratory conditions. Based on the distribution of mites in wheat, Triticum aestivum L., grain along a thermal gradient from 10 to 40 degrees C, L. destructor, D. farinae, and A. siro were classified as eurythermic and T. putrescentiae as stenothermic. The lowest preferred temperature was found for D. farinae (28 degrees C), followed by A. siro (28.5 degrees C), L. destructor (29.5 degrees C), and T. putrescentiae (31.5 degrees C). The relationship between the respiration rate and the temperature was similar for all four mite species. The highest respiration was found in the range from 31 to 33 degrees C. This is approximately 2 degrees C higher than the preferred temperature of these species. The lower temperature threshold of respiration ranged from 1 to 5 degrees C and the upper threshold ranged from 45 to 48 degrees C. Acclimatization of A. siro to temperature regimes of 5, 15, and 35 degrees C resulted in thermal preferences between 9 and 12 degrees C, 9 and 20 degrees C, and 28 and 35 degrees C, respectively. The respiration rate of acclimatized specimens increased with the temperature, reaching a maximum at 29.0 degrees C for mites acclimatized at 5 and 15 degrees C and a maximum at 33.7 degrees C for those acclimatized at 30 degrees C.     

Effects of thermoperiods on diapause induction in the cabbage beetle, Colaphellus bowringi (Coleoptera: Chrysomelidae)

Abstract. The effects of thermoperiods on diapause induction in continuous darkness or under a 12 : 12 h LD photoperiod were investigated in the cabbage beetle, Colaphellus bowringi Baly, a typical short‐day species. The diapause response curves both at different constant temperatures and at the thermocycle of format CT x: (24 ? x) h (16 : 28 °C) under continuously dark rearing conditions showed that the incidence of diapause depended mainly on whether or not the mean temperature was ≤20 °C or >20 °C. If the mean temperature was ≤20 °C, all individuals entered diapause; if >20 °C, the incidence of diapause declined gradually with increasing mean temperatures. The thermocycle (CT 12 : 12 h) with a series of different cryophases (8–22 °C) and thermophases (24–32 °C) under continuous darkness demonstrated a cryophase response threshold temperature of approximately 19 °C and a thermophase response threshold temperature of approximately 31 °C. Thermoperiodic amplitude (temperature difference between cryophase and thermophase) was shown to have a significant influence on diapause induction at the mean temperatures of 22, 23 and 24 °C, but not at ≥25 °C. Thermoperiodic responses under LD 12 : 12 h clearly showed that the incidence of diapause was influenced strongly by the photophase temperature. The thermoperiod under LD 12 : 12 h induced a much lower incidence of diapause than the thermoperiod with the same temperature in continuous darkness. The ecological significance of thermoperiodic induction of diapause in this species is discussed.     

Effect of thermoperiod on diapause intensity in Pyrrhocoris apterus (Heteroptera Pyrrhocoridae)

The intensity of adult diapause in Pyrrhocoris apterus was measured in two series of experiments as the duration of pre-oviposition period at a constant temperature of 25 degrees C after transfer from short (12L:12D) to long day conditions (18L:6D). Higher diapause intensity was induced with a thermoperiod than at constant temperatures. After the induction throughout larval instars 3-5 and during 4 weeks of adult life at short days and a thermoperiod of 25/15 degrees C the pre-oviposition period was 30+/-4 and 26+/-3 days. After induction at constant 25 degrees C the pre-oviposition period was 22+/-3 and 23+/-4 days, while after induction at constant 20 degrees C it was 17+/-4 and 19+/-4 days. Induction at a lower constant temperature of 20 degrees C was thus followed by a less intense diapause than the induction at a higher constant temperature of 25 degrees C. These counterintuitive results are discussed. The oxygen consumption rate measured at experimental temperatures prior to transfer from short to long days was higher at thermoperiodic conditions than at constant temperatures and it was similar at constant 20 and 25 degrees C. Thus, the oxygen consumption rate measured prior to the transfer was highest (indication of the least intense diapause) in the insects that showed later, after the transfer to long days, the longest pre-oviposition period (indication of the most intense diapause). Within the first two days after transfer to constant 25 degrees C, oxygen consumption rate measured at 25 degrees C decreased in the thermoperiodic insects, while it transiently increased in insects from constant 20 degrees C. Two days and later after the transfer, oxygen consumption rate was similar in all groups. Cold hardiness was not correlated with diapause intensity. The low lethal temperature in diapausing insects was correlated with the night temperature during diapause induction.     

Demography of soybean aphid (Homoptera: Aphididae) at summer temperatures

Soybean aphid, Aphis glycines Matsumura, is now widely established in soybean, Glycine max L., production areas of the northern United States and southern Canada and is becoming an important economic pest. Temperature effect on soybean aphid fecundity and survivorship is not well understood. We determined the optimal temperature for soybean aphid growth and reproduction on soybean under controlled conditions. We constructed life tables for soybean aphid at 20, 25, 30, and 35 degrees C with a photoperiod of 16:8 (L:D) h. Population growth rates were greatest at 25 degrees C. As temperature increased, net fecundity, gross fecundity, generation time, and life expectancy decreased. The prereproductive period did not differ between 20 and 30 degrees C; however, at 30 degrees C aphids required more degree-days (base 8.6 degrees C) to develop. Nymphs exposed to 35 degrees C did not complete development, and all individuals died within 11 d. Reproductive periods were significantly different at all temperatures, with aphids reproducing longer and producing more progeny at 20 and 25 degrees C than at 30 or 35 degrees C. Using a modification of the nonlinear Logan model, we estimated upper and optimal developmental thresholds to be 34.9 and 27.8 degrees C, respectively. At 25 degrees C, aphid populations doubled in 1.5 d; at 20 and 30 degrees C, populations doubled in 1.9 d.     

Temperature-dependent development and population growth of Tetraneura nigriabdominalis (Homoptera: Pemphigidae) on three host plants

The root aphid Tetraneura nigriabdominalis (Sasaki) (Homoptera: Pemphigidae) is a pest of many Gramineae species; however, little is known about its biology and relationships with host plants. The objectives of this study were to quantify the effects of temperature on development, longevity, fecundity, and population growth of T. nigriabdominalis and to assess the effects of host plant on development of T. nigriabdominalis. The effects of temperature on performance of this root aphid were determined at 10, 15, 20, 25, 30, and 35 +/- 1 degrees C on rice roots, Oryza sativa L. Nymphal stages from birth to adult decreased from 46.3 d at 10 degrees C to 8.5 d at 30 degrees C. Aphid survival and development were lowest at 35 degrees C, and no aphid produced progeny at this temperature. Average adult longevity decreased from 23.3 d at 15 degrees C to 8.2 d at temperatures up to 35 degrees C. Average number of nymphs produced per female was highest at 25 degrees C; averaging near 30 nymphs per female, but it dropped to near zero at both 10 and 35 degrees C. The highest intrinsic rate of increase (r(m)) was 0.241 at 30 degrees C. Net reproductive rate (R(0)) ranged from 29.8 at 25 degrees C to 0.2 at 10 degrees C. The generation time (GT) decreased with increasing temperatures from 60.3 d at 10 degrees C to 13.8 d at 30 degrees C. In addition, root aphids reared at 30 degrees C on three host plants [O. sativa, Zea mays L. and Sorghum bicolor (L.) Moench] revealed that the developmental time of the nymphal stages averaged 6.9 d when reared on O. sativa and 10.7 d when reared on Z. mays. Comparison of the nitrogen content of the three host plants indicated that the root nitrogen content was highest in O. sativa. The effect of nitrogen content on aphid performance, however, is still not clear. Other factors, such as plant secondary chemistry, may play a role in affecting aphid performance.     

温度对豆荚野螟实验种群的影响

作为豆科蔬菜上的重要害虫 ,豆荚野螟 Maruca testulalis Geyer能够对豆科蔬菜造成严重危害。研究温度对豆荚野螟不同虫期发育的影响 ,可以有利掌握其种群动态 ,以便进行有效控制。研究了室内不同温度条件下豆荚野螟的生长发育情况 ,发现在2 0～ 32℃温度范围内 ,随温度上升发育历期缩短 ;对于不同的生活史阶段 ,豆荚野螟卵、1～ 4龄幼虫、蛹及整个世代受温度影响显著 ;并计算得出完成全世代发育起点温度为 7.84℃ ,有效积温达 4 74 .2 0℃。通过内禀增长率参数的比较 ,认为各参数与温度的关系均达到极显著相关 ,以 2 9～ 32℃为豆荚野螟最适温度     

Survival of indianmeal moth and navel orangeworm (Lepidoptera: Pyralidae) at low temperatures

Concerns over insect resistance, regulatory action, and the needs of organic processors have generated renewed interest in developing nonchemical alternative postharvest treatments to fumigants used on dried fruits and nuts. Low-temperature storage has been identified as one alternative for the Indianmeal moth, Plodia interpunctella (Hiibner), and navel orangeworm, Amyelois transitella (Walker) (Lepidoptera: Pyralidae), common postharvest pests in California dried fruits and nuts. The response of eggs, nondiapausing larvae, and pupae of both species to exposure to low temperatures (0, 5, and 10 degrees C) was evaluated. Eggs of both species were the least tolerant of low temperatures. At 0 and 5 degrees C, pupae were most tolerant, but at 10 degrees C, nondiapausing larvae of both species were most tolerant, with lethal time (LT)95 values of 127 and 100 d for Indianmeal moth and navel orangeworm, respectively. The response of diapausing Indianmeal moth larvae to subfreezing temperatures also was evaluated. Diapausing larvae were very cold tolerant at -10 degrees C, with LT95 values of 20 and 17 d for long-term laboratory and recently isolated cultures, respectively. Diapausing larvae were far less tolerant at lower temperatures. At -15 degrees C, LT95 values for both cultures were <23 h, and at -20 degrees C, LT95 values were <7 h. Refrigeration temperatures of 0-5 degrees C should be useful in disinfesting product contaminated with nondiapausing insects, with storage times of 3 wk needed for adequate control. Relatively brief storage in commercial freezers, provided that the temperature throughout the product was below -15 degrees C for at least 48 h, also shows potential as a disinfestation treatment, and it is necessary when diapausing Indianmeal moth larvae are present.     

The effect of temperature on slaughterhouse wastewater treatment in anaerobic sequencing batch reactors

High strength slaughterhouse wastewater was treated in four 42 l anaerobic sequencing batch reactors (ASBRs) operated at 30 degrees C, 25 degrees C and 20 degrees C. The wastewater contained between 30% and 53% of its chemical oxygen demand (COD) as suspended solids (SS). The ASBRs could easily support volumetric organic loading rates (OLRs) of 4.93, 2.94 and 2.75 kg/m3/d (biomass OLRs of 0.44, 0.42 and 0.14 g/g volatile SS (VSS)/d) at 30 degrees C, 25 degrees C, and 20 degrees C, respectively. At all operating temperatures, the total COD (TCOD) and soluble COD (SCOD) were reduced by over 92%, while average SS removal varied between 80% and 96%. Over the experimental period, 90.8%, 88.7% and 84.2% of the COD removed was transformed into methane at 30 degrees C, 25 degrees C and 20 degrees C, respectively. The decrease in the conversion of the COD removed into methane as operating temperature was lowered, may be partly explained by a lower degradation of influent SS as temperature was reduced. The reactors showed a high average methanogenic activity of 0.37, 0.34 and 0.12 g CH4-COD/gVSS/d (22.4, 12.7 and 11.8 l/d) at 30 degrees C, 25 degrees C and 20 degrees C, respectively. The average methane content in the biogas increased from 74.7% to 78.2% as temperature was lowered from 30 degrees C to 20 degrees C.     

Effect of Temperature on the Coproduction of Chlortetracycline and Tetracycline by Streptomyces aureofaciens

Five strains of Streptomyces aureofaciens of diverse origin and ability to incorporate chloride into chlortetracycline (CTC) were grown at five temperatures of incubation ranging from 20 to 31 C in media of high and low chloride content. Maximal accumulation of CTC and tetracycline (TC) occurred in the 23 to 25 C range. Departure from this range affected the different strains to various degrees in total accumulation. Lower temperatures favored a relative increase in the amount of CTC produced by all strains. Higher temperatures were conducive to the almost exclusive production of TC by some strains but at the expense of an 80 to 90% reduction in potential total yield obtained at lower temperatures. The optimal temperature for maximal biochemical chlorination by some strains of S. aureofaciens was less than the optimal temperature for maximal accumulation of the tetracycline nucleus.     

Temperature dependent development of the parasitoid Colpoclypeus florus (Hymenoptera: Eulophidae) in the laboratory

Development, fecundity, and longevity of Colpoclypeus florus (Walker), a parasitoid of Adoxophyes orana (Fischer von R?slerstamm) (Lepidoptera: Tortricidae), were studied under laboratory conditions at different constant temperatures. Developmental time from egg to adult was inversely related to temperature and at 25 degrees C was 12.81 +/- 0.19 d. No adults emerged at 30 degrees C. The thermal units required for development from egg to adult were 232.56 +/- 19.5 degree-days. Female C. florus oviposited (mean +/- SEM) on average 30.7, 57.4, 46.6, and 34.1 eggs at 15, 17, 20, and 25 degrees C. respectively. Adult longevity was 11 +/- 1.25 d at 17, whereas it decreased to 4.5 +/- 0.4 at 25 degrees C. Honey significantly increased longevity for both males and females. The highest net reproductive rate was 30.739 at 17 degrees C, whereas the highest intrinsic rate of increase and the shortest doubling time occurred at 25 degrees C.     

Development, survival, and reproduction of the psocid Liposcelis yunnaniensis (Psocoptera: Liposcelididae) at constant temperatures

We investigated the effects often constant temperatures (20.0, 22.5, 25.0, 27.5, 30.0, 32.5, 35.0, 37.5, 39.0, and 41.0 degrees C) on the development, survival, and reproduction of the psocid Liposcelis yunnaniensis Li & Li (Psocoptera: Liposcelididae). At 39.0 and 41.0 degrees C, none of individuals could develop successfully or reproduce. From 20 to 37.5 degrees C, the development period from egg to adult ranged from 64.3 d at 20 degrees C to 16.1 d at 35 degrees C. The lower developmental threshold for egg, nymph, and combined immature stages were estimated at 15.08, 15.13, and 14.77 degrees C, respectively. After emergence the females went through a preoviposition period that ranged from 18.5 d at 22.5 degrees C to 3.11 d at 35 degrees C, whereas it was 16.3 d at 20 degrees C. Liposcelis yunnaniensis produced most eggs at 35 degrees C and the fewest at 22.5 degrees C. The population reared at 35 degrees C had the highest intrinsic rate of increase, shorter mean generation time, and shortest population doubling time compared with other temperatures. According to Weibull frequency distribution, L. yunnaniensis reared at all the temperatures had type III survivorship curves (c < 1.0). Based on life-table parameter estimations, we suggest that optimum range of temperatures for this species is from 25 to 37.5 degrees C. These data give us useful information on population biology of L. yunnaniensis and can be used to better manage this species.     

Macrolophus pygmaeus (Hemiptera: Miridae) population parameters and biological characteristics when feeding on eggplant and tomato without prey

The population parameters and biological characteristics of the predator Macrolophus pygmaeus Rambur when feeding on eggplant, Solanum melongena L., and tomato, Lycopersicon esculentum (Miller) (both Solanaceae), without access to prey, were investigated at several temperatures. The experiments were conducted at 15, 20, 25, and 30 degrees C, 65 +/- 5% RH, and a photoperiod of 16:8 (L:D) h. Females oviposited on both plant species at all temperatures, with the exception of tomato at 30 degrees C. Fecundity was highest at 20 degrees C (21.55 and 8.28 eggs per female on eggplant and tomato, respectively). Adult longevity on both host plants was greatest at 15 degrees C, reaching 38.72 and 34.20 d for females and 92.88 and 62.80 d for males, on eggplant and tomato, respectively. The estimated values of population parameters showed that this predator increased its numbers on eggplant at all temperatures tested, but the highest intrinsic rate of increase occurred at 25 degrees C (0.0401 d(-1)). On tomato, this predator could not increase in number, although it could survive for a relatively long period. Results demonstrated that M. pygmaeus can survive on both host plants in periods of prey scarcity, particularly on eggplant. Therefore, phytophagy can positively contribute to the effectiveness of this biological control agent. The importance of eggplant as a reservoir for the predator in mixed crops that are less suitable host plants is discussed.     

Influence of temperature on developmental rate,wing length,and larval head capsule size of pestiferous midge Chironomus crassicaudatus (Diptera: Chironomidae)

Larvae of Chironomus crassicaudatus Malloch were reared individually at nine constant temperatures from 12.5 to 32.5 degrees C (2.5 degrees C increments) for 120 d. Duration of immature stages (egg, four instars, and pupa), head capsule width of fourth instars, and wing length were recorded. Some adults emerged at all temperatures, except at 12.5 degrees C where individuals developed to fourth instars during the experiment. Sharpe and DeMichele's four-parameter model with high-temperature inhibition described the temperature-dependent developmental rates. The slowest development was observed at 15 degrees C, with developmental rate peaking between 25 and 27.5 degrees C. Developmental rate increased rapidly with increasing temperature up to 20 degrees C, slowed between 20 and 27.5 degrees C, and decreased at temperatures >27.5 degrees C. No developmental inhibition at high temperatures was observed in eggs. The most apparent high-temperature inhibition of development was recorded in fourth instars, which comprised the largest proportion of developmental time. Males developed faster than females, but females had wider larval head capsules and longer wings than males. Adult size was negatively related with temperature in both sexes, but this relationship was steeper in males than in females. Larval size peaked at 20 degrees C, whereas the head capsule width was reduced at temperatures higher and lower than 20 degrees C.