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Developmental time of the predatory mite Neoseiulus cucumeris (Oudemans) fed on cattail and almond pollen was determined under laboratory conditions at nine constant temperatures: 10, 15, 20, 25, 27, 30, 32, 35 and 38°C. No development was observed at 10°C. The lower temperature threshold (T 0) was estimated to be 10. 97 and 10. 29°C for the almond and cattail pollen, respectively, using the Ikemoto linear model. Thermal constant (K) for pre-adult development of N. cucumeris was 112.8 and 123.5 DD fed on almond and cattail pollen, respectively, using the Ikemoto linear model. The interaction between diet and temperature had a significant effect on the developmental rate of N. cucumeris. The nonlinear Pradhan-Taylor, Janisch/Kontodimas, Briere-1, and Janisch/Rochat models best described the developmental rate of pre-adult stages of N. cucumeris. The estimated T fast by Pradhan-Taylor model was 31.9 and 33.9°C when fed on almond and cattail pollen, respectively, which was similar to the observed shortest developmental time at 32°C. Our results revealed that N. cucumeris could develop over a wide temperature range (15–35°C), which is a desirable characteristic for a biocontrol agent in biological control programs. [ABSTRACT FROM AUTHOR]

We investigated the effects of seven temperatures (22.5, 25.0, 27.5, 30.0, 32.5, 35.0, and 37.5°C) and four relative humidities (43, 55, 63, and 75%) on population growth and development of the psocid Liposcelis fusciceps Badonnel (Psocoptera: Liposcelididae). Results demonstrated that L. fusciceps did not survive at 43% RH, at all temperatures tested. At 55% RH, L. fusciceps did not survive at the highest three temperatures and no psocids survived at 37.5°C and 63% RH. The highest population growth was recorded at 30.0°C and 75% RH where populations increased 16-fold from an initial population of five females. L. fusciceps males have two to four nymphal instars, and the percentages of males with two, three, and four instars were 28, 70, and 2%, respectively. Female L. fusciceps have two to five instars, and the percentages of females with two, three, four, and five instars were 2, 33, 63, and 2%, respectively. The total developmental time for males was shorter than females. We developed temperature-dependent development equations for male and female eggs, individual nymphal, combined nymphal, and combined immature stages. Based on 30-d population growth, L. fusciceps can survive and multiply at a relative humidity of 55% at 22.5-30.0°C, but does better at 27.5-32.5°C and a higher relative humidity of 75%. Relative humidities of≤63% and temperatures of≥32.5°C are detrimental to L. fusciceps. These data provide a better understanding of L. fusciceps population dynamics and can be used to develop effective management strategies for this psocid. [ABSTRACT FROM AUTHOR]

Aedes albopictus (Skuse) is an invasive mosquito species that has spread to many countries in temperate regions bordering the Mediterranean basin, where it is becoming a major public health concern. A good knowledge of the thermal features of the most productive breeding sites for Ae. albopictus is crucial for a better estimation of the mosquitoes' life cycle and developmental rates. In this article, we address the problem of predicting air temperature in three microhabitats common in urban and suburban areas and the air and water temperature inside an ordinary catch basin, which is considered the most productive breeding site for Ae. albopictus in Italy. Temperature differences were statistically proven between the three microhabitats and between the catch basin external and internal temperature. The impacts on the developmental rates for each life stage of Ae. albopictus were tested through a parametric function of the temperature, and the aquatic stages resulted as being the most affected using the specific temperature inside a typical catch basin instead of a generic air temperature. The impact of snow cover on the catch basin internal temperature, and consequently on the mortality of diapausing eggs, was also evaluated. These data can be useful to improve epidemiological models for a better prediction of Ae. albopictus seasonal and population dynamics in central-northern Italian urban areas. [ABSTRACT FROM AUTHOR]

We present a general and flexible mathematical model (called SANDY) that can be used to describe many biological phenomena, including the phenology of arthropods. In this paper, we demonstrate how the model can be fitted to vital rates (i.e., rates associated with development, survival, hatching, and oviposition) of the two-spotted spider mite (Tetranychus urticae (Koch)) exposed to different constant temperatures ranging from 15°C to 37.5°C. SANDY was incorporated into an age-, stage- and sex-structured dynamic model, which was fitted to cohort life-tables of T. urticae conducted at five constant temperatures (15, 20, 25, 30, and 35°C). Age- and temperature-dependent vital rates for the three main stages (eggs, immatures, and adults) constituting the life-cycle of mites were adequately described by the SANDY model. The modeling approach allows for simulating the growth of a population in a variable environment. We compared the predicted net reproductive rate (R0) and intrinsic rate of natural increase (rm) at fluctuating temperatures with empirical values obtained from life-table experiments conducted at temperatures that changed with a daily amplitude (±0, ±3, ±6, ±9, and ±12°C) around an average of 22°C. Results show that R0 decreases with increasing amplitude, while rm is more robust to variable temperatures. An advantage of SANDY is that the same simple mathematical expression can be applied to describe all the vital rates. Besides, the approach is not confined to modeling the influence of a single factor on population growth but allows for incorporating the combined effect of several limiting factors, provided that the combined effect of the factors is multiplicative. [ABSTRACT FROM AUTHOR]

The currently accepted lower threshold temperature for the development of diamondback moth, Plutella xylostella (Lepidoptera: Plutellidae), the world's most destructive insect pest of cruciferous crops, is around 6.0°C, and there is no known upper threshold temperature. Neither are there established threshold temperatures for diamondback moth's major natural enemy, Diadegma insulare (Hymenoptera: Ichneumonidae). Laboratory studies were undertaken to determine the survival and development of a North American diamondback moth population and its parasitoid D. insulare at 20 constant temperatures ranging from 2.0 to 38.0°C. Diamondback moth completed development from second instar to adult within a temperature range of 4.0-37°C, and D. insulare completed its life cycle from egg to adult within a temperature range of 4.0-33°C. The developmental data were fitted into one linear and four nonlinear models. Using goodness-of-fit and the ability to estimate parameters of biological significance as selection criteria, the Wang model was the most acceptable among the nonlinear models to describe the relationship between temperature and development of both species. According to this model, the lower and upper threshold temperatures for diamondback moth were 2.1 and 38.0°C, respectively, and for D. insulare they were 2.1 and 34.0°C, respectively. Based on the Degree Day model, diamondback moth required 143 d above the lower threshold of 4.23°C to complete the life cycle, while D. insulare required 286 d above the lower threshold of 2.57°C. This study suggests that temperatures during the crop-growing seasons in North America are not limiting factors for development of either diamondback moth or D. insulare. [ABSTRACT FROM AUTHOR]

The nonbiting midge, Glyptotendipes tokunagai Sasa (Diptera: Chironomidae), is an organism that can be used as a water quality indicator. Development of this insect under different temperatures was evaluated. The highest egg hatching rate was 99.12 ± 1.47% at 30°C, and the lowest was 84.50 ± 11.09% at 10°C. No eggs hatched at temperatures of 8 and 42°C. Developmental rate (1 / h) increased gradually as temperature increased from 10 to 35°C with a peak rate (0.045 ± 0.0079) at 35°C. The estimated lower thermal threshold for egg hatching was 9.3°C. Adult emergence rate was highest (80.6%) at 30°C and lowest (22.2%) at 15°C. The developmental times (egg to adult) for both males and females decreased from 2,102.6 to 457.2 h and from 2,337.1 to 619.8 h as temperatures increased from 10 to 30°C. The estimated lower thermal thresholds for males and females were 11.4 and 10.4°C, respectively. The body sizes of all G. tokunagai decreased as temperature increased from 15 to 35°C. From the results of this study, the approximate rearing temperature for G. tokunagai is suggested to be 25-30°C for egg hatching, larval development, and emergence. Our results demonstrate that G. tokunagai is a potential test insect species that can be reared in the laboratory by providing optimal temperature conditions. [ABSTRACT FROM AUTHOR]

Xylotrechus arvicola Olivier (Coleoptera: Cerambycidae) has become a new expanding pest in grape (Vitis spp.) crops. To better improve control tactics, the consequences of 11 constant (12, 15, 18, 21, 24, 27, 30, 32, 34, 35 and 36°C) and nine variable temperatures (with equal mean temperatures at each of the nine constant rates ranging from 15 to 35°C) on survival and embryonic development were studied. The eggs were able to complete development at constant temperatures between 15 and 35°C, with mortality rates at the extremes of the range of two and 81.5%, respectively. Using variable temperatures a mortality rate of 38.9% at a mean temperature of 15°C and 99% at 35°C was observed. The range of time for embryonic development was 29.5 d at 15°C to 6 d at 32°C at constant temperatures, and from 29.6 d at 15°C to 7.2 d at 32°C at variable temperatures. The goodness-of-fit of different development models was evaluated for the relationship between the development rate and temperature. The models that gave the best fit were the Logan type m for constant temperatures and the Brière for variable temperatures. Optimum temperatures were estimated to be from 31.7 to 32.9°C. The models that best described embryo development under natural field conditions were the Logan type m model for constant temperatures (98.7% adjustment) and the Lactin model for variable temperatures (99.2% adjustment). Nonlinear models predicted faster development at constant temperatures and slower development at variable ones when compared with real field development, whereas the linear model always predicted faster development than what actually took place. [ABSTRACT FROM AUTHOR]

Aulacorthum solani ( Kaltenbach ) ( known as foxglove aphid or glasshouse potato aphid ) is a pest of increasing economic importance in several agricultural crops worldwide, including greenhouse vegetables and ornamentals. Developmental rates and age-specific life tables for a North American population of A. solani on pansy (Viola X wittrockiana) (Gams.) were determined at six constant temperatures, and comparisons were made to previous studies of A. solani from differing geographic regions and host crops. On pansy, A. solani developed fastest at 25°C, passing through the four nymphal instars in an average of 6.9 d. The highest intrinsic rates of population increase (0.410 and 0.445) and shortest population doubling times (1.69 and 1.56 d) were recorded at 20 and 25°C, respectively. Average total fecundity remained high from 10 to 20°C (74-68 nymphs/adult); a significant decrease to 39 nymphs/adult occurred at 25°C. For calculating developmental thresholds, we present here a method of adjusting the lower developmental threshold (tmin) using estimates from nonlinear models to provide an improved estimate of the thermal constant (K, in degree-days). We also call attention to the necessity of using a simulation method to estimate the true upper developmental threshold (Tmax) and optimum developmental temperature (Topt) from the Lactin-2 model of temperature-dependent development. [ABSTRACT FROM AUTHOR]

The alfalfa root weevil, Sitona discoideus (Coleoptera: Curculionidae), is an important pest of alfalfa. The developmental rates of the embryo development were recorded at eight constant temperatures ranging from 8.5 to 30°C. Using 10 models (1 linear and 9 nonlinear), we evaluated the relationship between constant temperature and developmental rate. Embryo development was short- est (8.5 d) and longest (69 d), at 28 and 8.5°C, respectively. The threshold temperature (T0) and the thermal constant (K) were estimated using linear regression to be 4.7°C and 207.7 DD, respectively. The two most efficient nonlinear models, the Lactin and the Sharp and DeMichele, gave estimates of Tmin and Tmax of 4.4 and 3.9 and 30.0 and 30.9°C, respectively. This information has potential application in predicting the suitability and optimal time of release of an egg parasitoid of S. discoideus. [ABSTRACT FROM AUTHOR]

The invasive Brazilian peppertree (Schinus terebinthifoliu.s Raddi), native to South America, is widely established throughout central and south Florida. The defoliating leaflet-roller Epi.simus utilis Zimmerman was selected as potential biocontrol agent of this invasive species. The objectives of this study were to determine development rate and survival of E. utilis at seven constant temperatures (10, 15, 20, 25, 30, 33, and 35°C) and generate prediction maps of the number of generations per year this species may exhibit in the United States. The rate of development of E. utilis as a function of temperature was modeled using linear regression to estimate a lower developmental threshold of 9.6°C and the degree-day requirement of 588. The Logan nonlinear regression model was used to estimate an upper developmental threshold of 33°C. Cold tolerance of E. utilis was examined using all insect stages, and each stage was exposed to three constant temperatures (10, 5,0°C) for 0.5, 1,2,4, and 8 d (or until all insects died). The pupal stage was the most cold tolerant with 100% mortality after 12 d at 0°C. The pupal lethal times at 5 (Ltime50 = 10 d, Ltime90 = 28 d) and 0°C (Ltime50 = 5 d, Ltime90 = 9 d) were used to generate isothermal lines to predict favorable regions for E. utilis establishment. A GIS map was generated to predict the number of generations of E. utilis (range, 0.5-9.8) across all Brazilian peppertree range in the United States. The potential for establishment of E. utilis and its probable distribution in the continental United States was examined. [ABSTRACT FROM AUTHOR]

The development period of immature stages of the green apple aphid, Aphis pomi (De Geer) (Homoptera: Aphididae), at six constant temperature regimens (20, 24, 28, 30, 32, and 34°C) was modeled to determine mathematical functions for simulating aphid development. Ten models (one linear and nine nonlinear) were used to describe the relationships between temperature and development rate of the different instars and stages of A. pomi (DeGeer) at constant temperatures. All models (except logistic and linear) provided accurate values for the optimum temperature for the first-, second-, third-, and fourth-instar larvae and for total development. The results suggest that, among four models (Hilbert and Logan, Lactin, Briere, and Analytis) that estimate all three parameters (tmin, topt, tmax), Lactin and Hubert and Logan models gave the most suitable fit of data. [ABSTRACT FROM AUTHOR]

The development, reproduction, and life history of Encarsia citrina Craw were studied in the laboratory on San Jose scale, Quadraspidiotus perniciosus (Comstock), at constant temperatures of 15, 17.5,20,25,27.5, and 30°C at 60-70% RH, and a photoperiod of 16:8 (L:D) h. Larval development did not occur at 15 and 30°C. Total developmental time varied from 22.7 d at 27.5°C to 47.4 d at 17.5°C. The lower development thresholds for larval, pupal, and egg to adult periods were 10.4,6.3, and 9.0°C, respectively. The number of degree-days required to complete development was 434.8. The average longevity of adults ranged from 34.3 d at 15°C to 8.0 d at 30°C. The average fecundity of females ranged from 96.3 eggs at 20°C to 40 eggs at 17.5°C. Life table parameters were also determined at four constant temperatures (17.5-27.5°C). The intrinsic rate of increase, rm, values for E. citrina ranged from 0.074 at 17.5°C to 0.176 at 27.5°C. The highest net reproductive rate, Ro, of 93.7 female offspring/female was estimated at 20°C. The mean generation time, T, ranged from 49.3 d at 17.5°C to 23.4 d at 27.5°C. The results of this study emphasize E. citrina survival and population growth under varied temperature conditions. [ABSTRACT FROM AUTHOR]

The root weevil Diaprepes abbreviatus (L.) was reared on artificial diet under controlled conditions of temperature and humidity. The lower thermal threshold for development of neonate larvae was estimated to be 15 deg. C. The growth rate of neonate larvae increased exponentially with increasing temperature up to 30 deg. C. The growth rate oflater instars, however, was suppressed at 30 deg. C and mortality was higher than that of larvae reared at 26 deg. C. Larvae reared as late instars only ( >56 d old), or continuously at 30 deg. C, had increased mortality and produced smaller adults than larvae reared at 22 and 26 deg. C. Larvae reared as late instars only (>56 d) or continuously at 22 deg. C had similar survival rates compared with those reared at 26 deg. C, and they emerged as larger adults compared with larvae reared at 26 or 30 deg. C. The time required for development from neonate to pupation was 125 +/- 3 d (mean +/- SEM, n = 38) at 26 deg. C. Duration of the pupal stage was inversely proportional to temperature between 22 and 30 deg. C. Pupal mortality was higher at 30 deg. Cthan at 22 or 26 deg. C. The total time required for a single generation from oviposition to adult emergence was estimated to be 154 d at26 deg. C and adequate humidity. Cumulative mean air and soil temperatures and rainfall for a location in central Florida were analyzed and presented for the period October 1991 through January 1999. [ABSTRACT FROM AUTHOR]