Life history and population growth parameters of Tyrophagus putrescentiae (Acari: Acaridae) on Fusarium graminearum in laboratory conditions

The life history of an acarid mite, Tyrophagus putrescentiae (Schrank), on Fusarium graminearum Clade was investigated at 25 ± 1°C, 60 ± 5% RH and a photoperiod of 16: 8 (L: D) h. Incubation period for egg hatch, larval and nymphal periods and adult longevity were 2.22 ± 0.06, 3.46 ± 0.12, 4.84 ± 0.16 and 10.05 ± 0.9 days, respectively. The average life span of males and females were 22.22 ± 1.21 and 19.08 ± 1.37 days respectively. Pre-oviposition, oviposition and post-oviposition periods were 2.22, 5.77 and 1.4 days respectively. Gross and net fecundity rates were obtained 76.2 and 23 eggs per female per generation respectively. Net reproduction rate was 12.5 female eggs per female per generation, and average daily oviposition rate was 5.7 eggs. The intrinsic and finite rates of population increase were 0.15 and 1.16 day-1 respectively. The mean generation time (T) and the mean doubling time (DT) were 16.74 and 4.59 days respectively. The population mainly (78%) consisted of eggs and larvae, and nymphs and adults represented only 22% of the population

Population fluctuation of Neoseiulus barkeri (Acari: Phytoseiidae) and its prey, Tetranychus urticae (Acari: Tetranychidae), in cucumber fields of Khorramabad, Iran

Population density and spatial distribution of Neoseiulus barkeri Hughes and its prey, Tetranychus urticae Koch, in cucumber fields of Sarab-e Chengaei region in west of the city of Khorramabad, Lorestan province, were studied in 2008-2009. The population densities of both species in the first year was higher than the second year. The population densities for T. urticae and N. barkeri reached their peaks in late July and late August 2008, respectively. In 2009, the population peaks for both species occurred in late August. The reaction of N. barkeri to different population densities of its prey, with linear regression, was described as density independent. It was also found that mated females of N. barkeri overwintered in soil. The Taylor's power law regression method was used for finding the spatial pattern of the predator and prey, which was aggregated for both species. The correlation between the population fluctuation and spatial distribution pattern of the pest and its predator can effectively help to improve the strategy for a successful IPM program

The influence of temperature on the functional response and prey consumption of Neoseiulus barkeri (Acari: Phytoseiidae) on Tetranychus urticae (Acari: Tetranychidae)

The foraging behavior of a natural enemy is greatly affected by temperature. The influence ofdifferent constant temperatures on the functional response and prey consumption of the mated female ofNeoseiulus barkeri Hughes on nymphal stages of Tetranychus urticae Koch was evaluated. Four ambienttemperatures (20, 25, 30 and 35 ± 1°C) and six prey densities (2, 4, 8, 16, 32 and 64 individuals) wereused during a 24-h period in functional response experiments. The effect of seven constant temperatures(15, 20, 25, 27, 30, 35 and 37 ± 1°C) on prey consumption of N. barkeri on nymphal stages of T. urticaewas also determined. Using the logistic regression, the type II functional response was determined foradult female of N. barkeri at all temperatures. The type II Rogers' model was used to estimate the valuesof the searching efficiency (a) and handling time (Th). The value of the searching efficiency increasedwith increasing temperature from 20 to 30°C (0.0364 to 0.0731 h-1 respectively), then decreased at 35°C(0.0646 h-1). The handling time of this predator decreased when the temperature increased from 20 to35°C, and the minimum value was observed at 35°C (0.5548 h). Similarly, temperature had a significanteffect on the prey consumption of adult females of N. barkeri over the range of 15-37ºC. The minimumand maximum daily prey consumption of whole immature stages of N. barkeri was observed at 15°C and35°C respectively. The highest and the lowest number of total preys consumed by all immature stages ofN. barkeri were 14.61 and 8.79 preys that occurred at 20°C and 15°C respectively. During the ovipositionperiod, the total prey consumption increased with increasing temperature from 15 (160.43 preys) to 30°C(286.71 preys) and then declined and reached to 191.57 preys at 37°C. The results of this studyunderscore the effect of temperature on searching efficiency and prey consumption of N. barkeri

The reproduction and population growth parameters of Anisopteromalus calandrae (Hym.: Pteromalidae), a parasitoid of Callosobruchus maculatus (Col.: Bruchidae)

The reproduction and population growth parameters of Anisopteromalus calandrae (Howard) on the 4th instar larvae of Callosobruchus maculatus (Fabricius) were investigated at temperature of 25 ± 1ï°C, 20 ± 5% R.H. and a photoperiod of 16: 8 (L: D) hours. Since the parasitoid eggs are laid inside the seeds where the host larvae live, egg hatch rate (hx) was assumed to be 1 (100%). As a result of this study, the gross and net fecundity and fertility rates were determined to be 306.51 and 236.25, respectively. The average number of eggs produced per female per day was obtained 11.48. The intrinsic and finite rates of increase on the 4th instar of C. maculatus were 0.163 and 1.18, respectively. The mean generation and doubling times were 35.30 and 4.24 days, correspondingly. The gross and net reproduction rates were 123.36 and 109.49 females/female/generation, respectively. The results of this study on the stable age distribution showed that 62.3 % and 37.7 % of the population belonged to immature stages and adults, respectively. The possible application of these results for biological control of C. maculatus is discussed

Changes of low molecular weight compounds of cryoprotectants in overwintering adults of Eurygaster integriceps (Hem.: Scutelleridae)

The Sunn pest, Eurygaster integriceps Puton, is a univoltine insect and considered as one of the most important pests of wheat and barley. The adults of E. integriceps migrate to higher altitude in mountains for about nine months to complete their aestivation and hibernation period. To measure the cryoprotectants compounds, the insects were collected monthly between August 2009 and May 2010 in an altitude of 2000 meters and from wheat fields on the outskirts of Kabudarahang in the province of Hamadan. The level of cryoprotectants was determined using high performance liquid chromatography (HPLC). The identified compounds were trehalose, glycerol, glucose, myo-inositol, ribitol and sorbitol. It appears that trehalose and glycerol are the major cryoprotectants. The amount of trehalose significantly increased from 1.36 µmol/g fresh weight (f. w.) in September to 8.26 µmol/g f. w. in December. The amount of glycerol (22.36 µmol/g f. w.) and glucose (8.97 µmol/g f. w.) were at their highest levels in February and December, respectively. The amount of total cryoprotectants significantly increased from 12.28 µmol/g f. w. in September to 44.07 µmol/g f. w. in February. Results show that the Sunn pest has a great capacity to synthesize various cryoprotectants