Spatial distribution of the natural enemies of the cotton aphid, and the comparison of its estimating procedures in cotton fields of Gorgan, Iran

Spatial distribution of different natural enemies of the cotton aphid, Aphis gossypii Glover, was determined by fitting data to either Poisson (random) or negative binomial (aggregated) distributions and calculating dispersion indices, during 2002 and 2003 growing seasons in cotton fields of Gorgan, northern Iran. Based on R2 and p-values of regression analysis, for most of the natural enemy groups, Taylorâs power law generally provided a more adequate description of variance/mean relationships than Iwaoâs patchiness regression model. Natural enemy populations, especially parasitoids, cecidomyiid species and coccinellid eggs, were aggregated during most of the growing season, and negative binomial models generally fitted the data sets better than the Poisson series in cotton fields. Percentage fit for some species such as larva and adult stages of chrysopids, adult stages of Coccinella septempunctata L. and Scymnus spp., and spider species, showed a distinct tendency to the Poisson distribution and low values of Taylorâs b index. There were no significant relationships between k (a measure of the amount of clumping in negative binomial distribution) and mean values, indicating the existence of a common k for the most of the natural enemy groups. These results can provide a reliable basis to develop proper sampling plans for estimating or classifying natural enemy populations in cotton fields of Gorgan

Life history traits of melon ladybeetle, Epilachna chrysomelina (Col.: Coccinellidae), on four host plant species

Melon ladybeetle, Epilachna chrysomelina (F.), is one of the key insect pests of cucurbit crops in Asia and North Africa. The development and reproduction of E. chrysomelina were studied on watermelon, snake cucumber, cucumber and melon under laboratory conditions. Mean total life cycle from egg to adult female was 21.3, 21.7, 26.0, and 21.3 days on the mentioned host plants respectively. Mean immature mortality was 70.12%, 77.00%, 76.99% and 79.89% on the same four host plants. The female of E. chrysomelina oviposited means of 212.90, 377.85, 168.00 and 194.00 eggs and had a mean longevity of 28.77, 48.00, 38.55 and 28.36 days on watermelon, snake cucumber, cucumber and melon respectively. The net reproductive rate was 34.85, 48.82, 22.33 and 17.39 and daily intrinsic rate of increase was 0.095, 0.103, 0.073 and 0.077 on the respective plants. Life table statistics showed that snake cucumber was the most suitable host plant for E. chrysomelina, followed by watermelon and melon, with cucumber least suitable

Functional response of Stethorus gilvifrons (Col.: Coccinellidae) to different densities of Eutetranychus orientalis (Acari: Tetranychidae) in laboratory

The stage specific functional response of the acarophagous ladybird beetle Stethorus gilvifrons Mulsant to varying densities of citrus brown mite Eutetranychus orientalis (Klein) eggs was examined in a simplified castor bean leaf arena under laboratory conditions. All stages of S. gilvifrons were individually isolated for 24 hours with different prey densities at 30ºC and a photoperiod of 14: 10 (L: D). The number of prey consumed by the predator was checked after 24 hours. Each larval stage of S. gilvifrons showed a type II functional response when 88 eggs out of 120 eggs were consumed by the fourth-instar larva. Based on the random predator equation, the estimated attack rates of S. gilvifrons were 0.065, 0.089, 0.143, 0.125 and 0.046 per hour while the estimated handling times stood at 0.141, 0.166, 0.150, 0.134 and 0.082 per hour for the first, second, third and fourth instar as well as the adult female respectively. The species S. gilvifrons showed to be an effective predator on E. orientalis under controlled conditions. The results suggest that the simultaneous use of the both fourth-instar larvae and adult females of the acarophagous ladybird beetle could increase the rate of predation in the field

Biology and population growth parameters of jasmine whitefly, Aleuroclava jasmini on four different orange cultivars

Biology and population growth parameters of Jasmine whitefly, Aleuroclava jasmini (Takahashi) were studied on four orange cultivars including Siavaraz, Valensia, Mars and Washangton under laboratory conditions (27 ± 1 oC, 60 ± 5% RH and 14: 10 h L: D). The mean immature developmental times of females on Siavaraz, Valensia and Mars were 31.38 ± 0.23, 28.43 ± 0.68 and 29.20 ± 0.67 days, respectively. A. jasmini survived only up to third nymphal instar on Washington cultivar. Immature mortality was 25.77 ± 0.43, 32.00 ± 0.29 and 32.00 ± 0.52% on the above cultivars, respectively. Mean sex ratios (percent of females) were 59.45 ± 0.45, 54.05±0.63 and 51.76 ± 0.44% on above mentioned cultivars, respectively. The mean females longevity was 3.40 ± 0.11, 5.15 ± 0.20 and 4.60 ± 0.22 days, respectively, on cultivars. Mean total fecundity was 25.53 ± 1.45, 40.00 ± 1.62 and 33.66 ± 1.87 eggs on cultivars, respectively. Intrinsic rate of increase (rm) was 0.055 ± 0.001, 0.065 ± 0.003 and 0.060 ± 0.002 number of female/female/ day and Net reproductive rate (R0) was 6.46 ± 0.51, 7.71 ± 0.54 and 11.41 ± 0.60 offspring/individualon the above mentioned cultivars. Finite rate of increase (λ) was 1.05 ± 0.001, 1.06 ± 0.003 and 1.07 ± 0.002 per days and Mean generation time (T) was 33.6 ± 0.221, 31.09 ± 0.435 and 31.69 ± 0.639 days on the above mentioned cultivars. Doubling time (DT) was 12.48 ± 0.106, 10.55 ± 0.186 and 9.02 ± 0.183 days on the above mentioned cultivars. Based upon the biological characteristics and life table parameters, Valensia was found to be the most suitable cultivars for development and reproduction of A. jasmini

Comparative development, reproduction and life table parameters of three populations of Thrips tabaci (Thysanoptera: Thripidae) on onion and tobacco

An investigation was carried out to study the developmental time, reproduction and life table of three populations of the onion thrips, Thrips tabaci Lindeman, on onion (Khorasan and Golestan populations) and also on tobacco (Mazandaran population) in the laboratory at 25°C, 50% RH and 16: 8 h L: D. The total life cycle from egg to adult of Khorasan, Golestan and Mazandaran populations were gauged as 15.22, 14.66 and 17.82 days, respectively. However, theses populations showed 30%, 38% and 58% immature mortality, respectively. The females of T. tabaci laid 29.5, 27.7 and 26.3 eggs averagely, and had a mean longevity of 18.0, 17.78 and 19.07 days in Khorasan Razavi, Golestan and Mazandaran populations, respectively. The net reproductive rate (R0) was 19.75, 18.48 and 10.84, and the intrinsic rate of increase (rm) was 0.143, 0.141 and 0.096 in Khorasan Razavi, Golestan and Mazandaran populations, respectively. Khorasan Razavi and Golestan populations (both reared on onion) had similar developmental time, mortality and life table parameters, while Mazandaran population (on tobacco) yielded significantly different values. Based on the differences of development, fecundity and life table parameters, there might be two distinct populations exploiting onion and tobacco in Iran

Report of the parasitoid wasp Eretmocerus delhiensis (Hym.: Aphelinidae) from Iran

The occurrence of the hymenopterous parasitoid of the sugarcane whitefly, Neomaskellia andropogonis Corbett (Hem.: Aleyrodidae), in Iran is newly reported. The aphelinid species, Eretmocerus delhiensis Mani, which was reared from nymphs of the sugarcane whitefly, belongs to the subfamily Aphelininae and tribe Eretmocerini

Study on daily and reproduction activity of melon weevil, Acythopeus curvirostris persicus (Col.: Curculionidae), in Birjand, Iran

Melon weevil, Acytopeus curvirostris persicus Thompson, is one of the most important pests of melons that is spread in the Middle East countries. In this study, diurnal and seasonal locomotor and flight activity of melon weevil were investigated under field condition using bucket traps (baited with conspecifics male and cucumber fruit) and also mating behavior pattern and its effect on fecundity (under semifield conditions) and fertility (under laboratory conditions). The results showed that both males and females of melon weevil have distinct daily activity. Two activity peaks were observed at 7:00-9:00 am and 17:00-19:00 pm. Maximum flight activity was observed in the afternoon (14:00 hours) in field condition. Both sexes emerged in early cultivation season (late June) simultaneously and the number of captured weevil was the highest in early October (6.1 ± 2.6 weevils per week). Emerged adults from pupal cocoon mated after about eight days. Peak of mating occurred during 14:30-16:30 pm. Number of mating during lifetime of males (18.3 ± 3.4) was nearly two times greater than females (9.6 ± 2.2). The mean number of eggs laid during reproduction period in single and multiple mating were 29.2 ± 3.5 and 52.4 ± 6.2 eggs per female, respectively. Oviposition was maximum on 12 and 36 days after mating. Hatching rates of eggs in single and multiple mating were 85 ± 7% and 82.5 ± 9%, respectively. Multiple mating had no significant effect on fecundity and fertility. There was no relationship between mating frequency and temperature

Effects of two host plants on the functional response of adult Orius albidipennis (Hem.: Anthocoridae) to different densities of the second instar larvae of Thrips tabaci (Thys.: Thripidae)

Thrips tabaci Lindeman, is one of the most important pests of vegetables and ornamental plants across the world. The functional response of Orius albidipennis Reuter was studied in relation to different densities of second instar larvae of T. tabaci. Laboratory experiments were conducted to evaluate the effect of two different host plants (cucumber and bean plantlets) on the functional response and its parameters (attack rate and handling time) using different densities of 2, 5, 10, 20, 30 and 40 thrips. The cucumber and bean plantlets, in relatively small pots with a diameter of 4 cm and 7 cm high were supplied to the predators to feed on the thrips in a 24-hour-period. Each density was repeated 10 times. The experiment was carried out at 25-29°C, 60 ± 5% R.H. and photoperiod of 16: 8 L: D hours. The logistic regression suggested a type II functional response on two host plants. The Rogerâs random predator equation was compatible with the results. The type of functional response was not affected by the host plants. Attack rate (a), handling time (Th) and maximum predation of O. albidipennis were 0.073 ± 0.013, 1.67 ± 0.12 and 14.37 on the cucumber and 0.095 ± 0.02, 1.51 ± 0.11 and 15.89 on the bean plantlets, respectively. There was no significant difference among estimated parameters in both plantlets

Electron Capture Dissociation Mass Spectrometry of Tyrosine Nitrated Peptides

In vivo protein nitration is associated with many disease conditions that involve oxidative stress and inflammatory response. The modification involves addition of a nitro group at the position ortho to the phenol group of tyrosine to give 3-nitrotyrosine. To understand the mechanisms and consequences of protein nitration, it is necessary to develop methods for identification of nitrotyrosine-containing proteins and localization of the sites of modification.Here, we have investigated the electron capture dissociation (ECD) and collision-induced association (CID) behavior of 3-nitrotyrosine-containing peptides. The presence of nitration did not affect the CID behavior of the peptides. For the doubly-charged peptides, addition of nitration severely inhibited the production of ECD sequence fragments. However, ECD of the triply-charged nitrated peptides resulted in some singly-charged sequence fragments. ECD of the nitrated peptides is characterized by multiple losses of small neutral species including hydroxyl radicals, water and ammonia. The origin of the neutral losses has been investigated by use of activated ion (AI) ECD. Loss of ammonia appears to be the result of non-covalent interactions between the nitro group and protonated lysine side-chains