Effect of temperature on developmental time and longevity of Psyttalia cosyrae (Hymenoptera: Braconidae)

Psyttalia cosyrae (Wilkinson) (Hymenoptera: Braconidae) is a koinobiont, solitary larval-pupal parasitoid of Ceratitis cosyra (Walker) (Diptera: Tephritidae), and possibly other tephritid fruit flies. The effect of temperature on developmental time and longevity of this parasitoid was investigated and the thermal requirement at six constant temperatures (15±0.5, 20±0.5, 25±0.5, 27±0.5, 30±0.5, and 33±0.05°C) and 60-70% R.H was determined. The developmental rate increased with an increase in temperature. Females took a longer time to complete development than males at all temperatures tested. Development from egg to adult emergence required 244 degree-days (DD) above a thermal threshold of 11.9°C for both sexes pooled, 233 DD above 12.0°C for males and 256 DD above 11.6°C for females. Adult longevity was affected by temperature, and females lived longer than males at all temperatures tested.     

Effect of temperature on parasitism and host-feeding of Trichogramma turkestanica (Hymenoptera: Trichogrammatidae) on Ephestia kuehniella (Lepidoptera: Pyralidae)

The egg parasitoid Trichogramma turkestanica Meyer is being evaluated as a biological control agent against the Mediterranean flour moth, Ephestia kuehniella Zeller, in flour mills. The longevity, parasitism and host-feeding of the parasitoid at four constant temperatures (15-30 degrees C) has been determined in the laboratory. The highest fecundity occurred at intermediate temperatures. The number of host eggs killed by host-feeding per female was highest at the two lower temperatures. A very conservative estimate of host-feeding showed that it accounts for approximately half of the mortality of host eggs at 20 and 25 degrees C and thus could constitute a major mortality factor for the flour moth population.     

Effect of Temperature on Development and Survival of Citrostichus phyllocnistoides (Hymenoptera: Eulophidae), a Parasitoid of Phyllocnistis citrella (Lepidoptera: Gracillariidae)

Thermal requirements of Citrostichus phyllocnistoides under laboratory conditions resulted in a lower temperature threshold of 9.8°C, and a thermal constant of 212.0 DD. Development was completed between 15 and 30°C, but was not at 10°C. Therefore, the overwintering of this exotic biocontrol agent would be possible under typical Mediterranean temperatures.     

Parasitism capacity of Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) reared under different temperatures on Bonagota salubricola (Meyrick) (Lepidoptera: Tortricidae) eggs

The parasitism capacity of Trichogramma pretiosum Riley strain bonagota on Bonagota salubricola (Meyrick) eggs was studied under the temperatures of 18, 20, 22, 25, 28, 30 and 32 degrees C. The number of days with parasitism, accumulated parasitism, total number of eggs parasitized per female and parasitoid longevity was evaluated. In the first 24h, parasitism ranged from 1.6 (32 degrees C) to 8.8 (22 degrees C) eggs of B. salubricola. Accumulated egg parasitism of B. salubricola reached 80% in 1st to 4th day at 20 degrees C to 32 degrees C, respectively, and in the 7th day at 18 degrees C. Temperatures from 18 degrees C to 22 degrees C were the best suited for the total eggs parasitized for female, resulting in 35.4 and 24.6 eggs/male respectively. T. pretiosum female longevity ranged from 7.8 to 2.5 days, at 18 degrees C and 32 degrees C, respectively. The results showed that T. pretiosum strain bonagota is better adapted to temperatures from 18 degrees C to 22 degrees C.     

Development of Aphidius colemani Viereck (Hym.: Braconidae, Aphidiinae) and alterations caused by the parasitism in the host Aphis gossypii Glover (Hem.: Aphididae) in different temperatures

Aphidius colemani Viereck is among the main natural enemies used for biological control of Aphis gossypii Glover. The objective of the present study was to evaluate the development of A. colemani and the alterations caused by the parasitism in the host A. gossypii in different temperatures and to estimate the thermal requirements of the parasitoid. The experiments were carried out in controlled environmental chambers at 16, 19, 22, 25, 28 and 31 +/- 1 degrees C, 70 +/- 10% RH, and 12h photophase. Second-instar nymphs of A. gossypii were parasitized once and kept individually in glass tubes (2.5 cm x 8.5 cm), containing leaf disc of cucumber (2 cm) and 1% water/agar solution. The development time of A. colemani, from oviposition to mummies (11.9, 9.8, 7.7, 6.4 and 6.4 days) and from oviposition to adult (19.4, 16.2, 12.6, 10.5 and 10.7 days) decreased with the increase of the temperature from 16 degrees C to 25 degrees C. The rates of mummies and the emergence of the parasitoid, and its longevity also decreased with the increase of the temperature. Mummies were not produced at 31 degrees C. The lower temperature threshold of A. colemani was 5.94 degrees C and its thermal constant was 200 degrees-day. The alterations caused by the parasitoid in the A. gossypii host were minimized at 31 degrees C, where 98% of the host did not show symptoms of parasitism and produced nymphs. The temperature of 22 degrees C was optimal for the development time of A. colemani.     

Does thermal-related plasticity in size and fat reserves influence supercooling abilities and cold-tolerance in Aphidius colemani (Hymenoptera: Aphidiinae) mummies?

(1) The parasitoid Aphidius colemani was reared at 15 or 25 °C to induce variation in size and fat reserves; SCP and cold-tolerance were compared. Insects from both temperatures were also exposed to constant or fluctuating cold-exposure.

(2) The lower SCP in mummies reared at 25 °C may be partially explained by their smaller size, a negative relationship being observed between SCP and size.

(3) A bimodality was observed in SCP distributions, with two modes around −26 and −22 °C, likely because of presence/absence of gut content.

(4) The type of exposure had a striking impact, mortality being considerably lower under fluctuating regime.

(5) While energy storage is an important factor, vulnerability to chill-injury is supposed to be the primary factor regulating survival at low temperature.     

Environmental Effects on the Development and Survival of the Scale Insect Abgrallaspis cyanophylli (Signoret) (Homoptera: Diaspididae) with Reference to its Suitability for Use as a Host for Rearing Biological Control Agents

Developmental and survival rates of the locally important diaspidid pest, Abgrallaspis cyanophylli (Signoret) reared on Solanum tuberosum L . tubers were examined under light and dark conditions; humidities of 33, 53, 62 and 75% relative humidity (RH); varying population densities; constant temperatures in the range of 20 to 30oC and at cycling temperatures of 12 h at 14°C and 12 h at 30°C. Developmental rate was slightly lower under constant light conditions but mortality was higher in the dark, particularly amongst the males. At 26°C, there were no differences in developmental rate in relation to the various humidity levels. However, survival was significantly lower at 33% RH, with females suffering higher mortality than males. Population density was found to have no effect on developmental rate or size of the females. Overall mortality increased in line with population density although the result was poorly correlated. Within the range 20-28°C developmental rate increased with rising temperature but decreased at 30°C. Thermal summation and polynomial regression data show a theoretical lower thermal threshold for development of 12.47°C. The thermal constant was 541.7 degree days. Survival was lowest at 20°C and 30°C and highest at temperatures in the median range and under cycling conditions. Male survival was significantly higher than that of the females at 30°C and under the cycling regime of 14/30°C. The results suggest that the optimum conditions for rearing A. cyanophylli on potatoes would be at temperatures in the range 24-26°C and humidities of 55-65% RH.     

The Influence of Host Species on Some Biological and Behavioural Aspects of Dibrachys boarmiae (Hymenoptera: Pteromalidae), Parasitoid of Kermania pistaciella (Lepidoptera: Tineidae)

Dibrachys boarmiae was recently found as a parasitoid of the pistachio twig borer moth, Kermania pistaciella, an important pistachio pest in Iran. Several biological and behavioural aspects of the wasp were studied under controlled conditions using three different lepidopterous host species, K. pistaciella, Sitotroga cerealella and Galleria mellonella. Development time from egg to adult decreases from 54 days at 15°C to 12.6 days at 32.5°C. The thermal constant was estimated 270°D, and the lower development threshold was at 9.9°C. Longevity of females that had the opportunity to oviposit and access to food (honey) was on average 23 days, and 134 offspring were produced during 13 days of oviposition. Ninety percent of ovipositions occur during the first 10 days of the parasitoid's life, although no pre-oviposition period was found. If females were deprived of food, longevity as well as fecundity, were drastically reduced to 8 days and only 79 offspring respectively. Females were able to mate immediately after emergence and the sex ratio of the progeny was strongly female biased on all examined hosts, especially on the largest host G. mellonella (0.08 male). When females were kept with a male throughout their life, the total number of progeny decreased to 92 wasps on average but the sex ratio was unaffected. The parasitoid significantly preferred to attack the pre-pupal stage, and this influenced the size of clutches allocated to different host stages. The parasitoid laid larger clutches on bigger hosts.     

Biological parameters and thermal requirements of the parasitoid Praon volucre (Hymenoptera: Braconidae) with Macrosiphum euphorbiae (Hemiptera: Aphididae) as host

The effect of temperature on the biology of Praon volucre (Haliday, 1833) (Hymenoptera: Braconidae) in Macrosiphum euphorbiae (Thomas, 1878) (Hemiptera: Aphididae) hosts was studied and the thermal requirements of the parasitoid were determined. Experiments were carried out at 16, 19, 22, 25, and 28 ± 1°C with 70 ± 10% relative humidity and 12 h photophase. The developmental time of P. volucre males and females decreased between 16 and 23°C. The highest percentages of aphid parasitism and adult parasitoid emergence were observed at 16, 19, and 22°C. The sex ratio (expressed as % females) decreased between 16 and 23°C. Male and female longevity was high between 19 and 22°C and decreased strongly at 25°C. The lower temperature threshold for P. volucre was 5.17°C and the thermal constant was 243 degrees-days.     

A large-scale rearing method for Peristenus digoneutis (Hymenoptera: Braconidae), a biological control agent of Lygus lineolaris (Hemiptera: Miridae)

Releases of Peristenus digoneutis against Lygus spp. in North America have been conducted for many years; however, no published procedures for mass production of the biological control agent were available. A laboratory rearing method was developed using Lygus lineolaris as the host to enhance establishment efforts and provide large numbers of wasps for inundative releases into high value fruit crops. Experiments were conducted to determine optimum host:parasitoid density and rearing temperature. The effects of nymph:wasp ratios and temperature on parasitism and wasp survival showed a 20:1 ratio at 20°C provided high parasitism (256 parasitized nymphs/wasp over lifetime) and excellent wasp survival of 27 days. Experiments on diapause-inducing conditions for P. digoneutis demonstrated that fluctuating temperatures of 23°C (day) and <16°C (night) and corresponding photo phases of 16 h light, for rearing parasitized nymphs, produced 100% diapausing parasitoids whereas non-diapausing parasitoids were only produced at more than 16 h light. Furthermore, parasitized Lygus nymphs need to be transferred to short day conditions no later than 10 days after parasitism to produce diapausing parasitoids. Critical life stages for exposure to conditions inducing diapause, the egg, first and second instar parasitoid larva, occurred from 0 to 10 days at 24°C constant temperature. Increased time in cold storage reduced the number of days to first emergence of parasitoids from diapausing cocoons when transferred to warm temperatures. The optimum storage time for diapausing P. digoneutis is between 25 and 44 weeks, depending upon the length of time that cocoons remain at warm conditions prior to chilling.     

Age-dependent fecundity and life-fertility tables for Podisus nigrispinus (Dallas) (Het., Pentatomidae)

Abstract: The reproductive potential and longevity of Podisus nigrispinus (Dallas) were determined under laboratory conditions at a constant temperature of 25°C. The data were used to calculate life-fertility tables and rates of increase. The fecundity plateau of P. nigrispinus lasted 18 days, and during this period mean fecundity was 8.89 eggs per female per day. It started at the eighth day of age and ended at the 18th day of age. The declining fecundity period started at 18 days of age and ended with the death of the females. The female of P. nigrispinus oviposited a mean of 188.54 eggs, and had a mean longevity of 31.21 days. The gross reproductive rate (GRR) was 104.374 females/female; the net reproductive rate ( R _o) was 31.945 females/female; the generation time was 47.390 days; the doubling time was 9.480 days; the intrinsic rate of increase ( r _m ) was 0.073, and the finite rate of increase ( λ ) was 1.076. The predator population increased by 16.61 adult progeny per female per generation in the laboratory.     

Effect of temperature on the development and viability of Gryon gallardoi (Brethes) (Hymenoptera: Scelionidae) parasitizing Spartocera dentiventris (Berg) (Hemiptera: Coreidae) eggs.

The development and viability of Gryon gallardoi (Brethes) (Hym.: Scelionidae) in Spartocera dentiventris (Berg) (Hem.: Coreidae) eggs were studied under four temperatures: 15, 20, 25, and 30 +/- 1 degree C, with a 12-h photophase. No parasitoid developed at 15 degrees C. Otherwise, viability reached 98.8% without varying significantly over the temperature range tested. The duration of development for males and females was inversely proportional to the temperature increase, varying respectively from 46.2 +/- 0.13 and 47.1 +/- 0.11 days (20 degrees C) to 13.3 +/- 0.07 and 13.4 +/- 0.06 days (30 degrees C). Males developed faster than females. The values estimated for the lowest thermic thresholds of development and the thermic constants were 15.5 degrees C and 185.19 DD for males and 15.6 degrees C and 192.31 DD for females, respectively. Given the average weather conditions in Porto Alegre, RS (30 degrees 01' S and 51 degrees 13' W), Brazil, G. gallardoi could annually produce 8.54 and 8.07 generations of males and females, respectively. The low rates of parasitism observed in the field during the first generation of its host may be due to the small number of G. gallardoi generations in this period.     

On the biology and thermal developmental requirements of the cotton mealybug,Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) in Egypt

This study evaluated the thermal requirements for development of the cotton mealybug Phenacoccus solenopsis depending on different biological parameters on Okra leaves Abelmoschus esculentusat under two constant temperatures (20 and 30 °C) at (RH 65%, 12:12 h. light/dark). The effect of temperature on eggs was ineffective since it hatched shortly to first nymphal instars after deposition. While the tested temperature caused significant effects on nymphal durations, pupation rate (pre-male stage), females emergence %, pre-oviposition, longevity, post-oviposition periods and fecundity in females (egg deposition, ovisacs numbers and hatchability %). The thermal constant and developmental zero were calculated to be 7.29 °C and 79.9 degree-days (DDs) for eggs, 11.67 °C and 272.9 DDs for nymphal stages, 11.06 °C and 46.4 DDs for males and then 3.31 °C and 554.1 DDs for females, respectively. The duration of the life cycle was 65.6 ± 10.36 days at 20 °C; this was shortened to 35.51 ± 1.12 days at 30 °C. The thermal requirements to complete the insect development for one generation was 8.2 °C for the developmental zero and 774.1 DDs for the thermal constant. Based on the thermal requirements values, the average life cycle duration from January to December 2016 was 61.78 days and the number of annual generations was 7.143 when the average annual temperature was 23.29 °C.     

Recurrent warming to improve cold storage of Trichogrammatids (Hymenoptera: Trichogrammatidae)

Cold storage can be used to slow development, facilitate accumulation of the organisms and accommodate fluctuating demand for augmentative biological control agents. Previous research suggested the possibility of improving cold storage of Trichogrammatids by recurrent warming, so we subjected Trichogramma ostriniae juveniles within Ephestia kuehniella host eggs to either 2°C constant or to 2°C with twice-weekly recurrent warming for 3 h to 20°C. Parasitoid subsamples were allowed to mature for 1–9 days before placement in cold storage for up to 8 weeks. Parasitism by parentals, progeny emergence and fecundity and longevity of progeny were measured weekly for 8 weeks. Relative to constant 2°C, recurrent warming generally improved emergence, fecundity and longevity, and all the response variables were affected by the interaction of temperature regimen, parasitoid maturity class, and cold storage duration. This implies the utility of recurrent warming to improve egg parasitoid performance and for extending the duration of cold storage.     

Stress intensity and fitness in the parasitoid Aphidius ervi (Hymenoptera: Braconidae): temperature below the development threshold combined with a fluctuating thermal regime is a must

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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.     

Changes in Biological Characteristics of Trichogramma pretiosum (Hym.: Trichogrammatidae) Reared on Eggs of Anagasta kuehniella (Lep.: Pyralidae) for 23 Generations

Possible changes in biological characteristics of Trichogramma pretiosum (Riley) (Hymenoptera: Trichogrammatidae) were monitored during 23 generations reared on eggs of Anagasta kuehniella (Zeller) (Lepidoptera: Pyralidae), to determine quality control parameters in rearing procedures of this parasitoid. Parasitism rates (percent of eggs parasitized) of T. pretiosum varied from 10 to 76%, with lower values for the first four generations. From the 17th generation, the variability in the parasitism rate was lower. Viability (percent adult emergence rate) of T. pretiosum in eggs of A. kuehniella varied from 22 to 100%, again with lower values in earlier generations. Adult longevity of T. pretiosum varied from 5.3 to 15.9 days, and showed a reduced longevity with increasing number of generations. Sex ratio of the offspring of this parasitoid was not affected by the timing of parasitism on eggs of A. kuehniella.     

Life history of Aptesis nigrocincta (Hymenoptera: Ichneumonidae) a cocoon parasitoid of the apple sawfly, Hoplocampa testudinea (Hymenoptera: Tenthredinidae)

Aptesis nigrocincta: Gravenhorst is a bivoltine ectoparasitoid of apple sawfly cocoons, hosts that must be found and parasitized by females at a depth of 10-25 cm in the soil. Females are significantly smaller than males and nearly wingless. After encountering a host, females needed 29.3 min at 20 degrees C and 19. 9 min at 25 degrees C to deposit an egg on the host. Development from egg to adult took 39.6 days for females and 38.0 days for males at 20 degrees C. This small difference was significant. At 20 degrees C, the longevity of females that had no opportunity to oviposit was on average 72.5 days, significantly higher than male longevity (50.6 days). The longevity of females given access to hosts throughout their lifetime averaged 58.6 days. Females were able to mate immediately after emergence and copulation lasted on average 21.7 s. After a pre-oviposition period averaging 5.8 days, females laid 20.2 eggs during their lifetime, thus less than one egg per day. Neither the fecundity nor longevity of individual females was correlated with body size. If females were deprived of food, longevity as well as lifetime fecundity were drastically reduced. Field studies were carried out in one organically managed apple orchard in Switzerland. Aptesis nigrocincta showed parasitism rates ranging from 12.1 to 39.7 % within single parasitoid generations, thereby constituting the most important mortality factor of apple sawfly cocoons.     

Reproductive and developmental biology of Gonatocerus ashmeadi (Hymenoptera: Mymaridae), an egg parasitoid of Homalodisca coagulata (Hemiptera: Cicadellidae)

The reproductive and developmental biology of Gonatocerus ashmeadi Girault, a parasitoid of the glassy-winged sharpshooter Homalodisca coagulata (Say), was determined at five constant temperatures in the laboratory: 15; 20; 25; 30; 33 °C. At 30 °C, G. ashmeadi maintained the highest successful parasitism rates with 46.1% of parasitoid larvae surviving to adulthood. Lifetime fecundity was greatest at 25 °C and fell sharply as temperature either increased or decreased around 25 °C. Temperature had no effect on sex ratio of parasitoid offspring. Mean adult longevity was inversely related to temperature with a maximum of 20 days at 15 °C to a minimum of eight days at 33 °C. Developmental rates increased nonlinearly with increasing temperatures. Developmental rate data were fitted with the modified Logan model for oviposition to adult development times across each of the five experimental temperatures to determine optimal and upper lethal temperature thresholds. The lower developmental threshold estimated by the Logan model and linear regression were 1.10 and 7.16 °C, respectively. Linear regression of developmental rate for temperatures 15–30 °C indicated that 222 degree-days were required above a minimum threshold of 7.16 °C to complete development. A temperature of 37.6 °C was determined to be the upper development threshold with optimal development occurring at 30.5 °C. Demographic parameters were calculated and pseudo-replicates for intrinsic rate of increase (r_m), net reproductive rates (R_o), generation time (T_c), population doubling time (T_d), and finite rate of increase (λ) were generated using the bootstrap method. Mean bootstrap estimates of demographic parameters were compared across temperatures using ANOVA and nonlinear regression.     

Life table of Tamarixia radiata (Hymenoptera: Eulophidae) on Diaphorina citri (Hemiptera: Psyllidae) at different temperatures

Tamarixia radiata (Waterston, 1922) is the main parasitoid of Diaphorina citri (Kuwayama, 1907), and has been used in classical biological control programs in several countries. The current study investigated the biology and determined the fertility life table of T. radiata in different temperatures, to obtain information to support the establishment of a biological control program for D. citri in Brazil. Fifth-instar nymphs of D. citri were offered to females of T. radiata for parasitism, for 24 h. Then, the parasitoid was removed and the nymphs were placed in incubators at 15, 20, 25, 30, or 35 +/- 1 degrees C, 70 +/- 10% RH, and a 14-h photophase. The percentages of parasitism and emergence, the sex ratio, and the preimaginal period of T. radiata were determined. The fertility life table was developed from the biological data. The highest parasitism rate (77.24%) was obtained at a temperature of 26.3 degrees C, and the lowest parasitism rates occurred at 15 and 35 degrees C (23.1 and 40.2%, respectively). The highest percentages of emergence of the parasitoid occurred at 25, 30, and 35 degrees C (86.7, 88.3, and 78.8%, respectively), with the calculated peak at 30.8 degrees C (89.90%). The duration of the preimaginal developmental period for both females and males of T. radiata was inversely proportional to temperature in the thermal range of 15-35 degrees C. The development of T. radiata occurred at all temperatures studied, and the highest viability of the preimaginal period occurred at 25 degrees C. The highest values of net reproductive rate and finite growth ratio (lambda) were observed at 25 degrees C, so that in each generation the population of T. radiata increased 126.79 times, higher than the values obtained at the other temperatures.