Insecticidal effect of plant extracts on common pistachio psylla,Agonoscena pistaciae Burckhardt and Lauterer (Hemiptera: Aphalaridae)

The common pistachio psylla, Agonoscena pistaciae (Hemiptera: Aphalaridae) is one of the most detrimental pests to pistachio trees. Nowadays various pesticides are used to control the common pistachio psylla, but extensive pesticide spraying against this pest over a period of several years has overpowered its natural enemies. The plant’s byproducts come as an alternative ecologically more compatible in substitution to the synthetic insecticides. This work aims to evaluate the insecticidal potential of herbal extracts of fruit peels of Citrus sinensis and Citrus reticulata, seeds of C. sinensis and Rubia tinctorum, and leaves of Lawsonia inermis against common pistachio psylla. Five concentration 40, 47, 56, 67 and 80 µl/ml, of these plant extracts were sprayed on the fifth instar nymphs of common pistachio psylla by Potter Spray Tower under laboratory conditions (26?±?2?°C, 60–70% RH and a photoperiod of 16L: 8D h). Results showed significant differences among the treatments of the plant extracts and between the concentrations. The LC₅₀ values of C. sinensis peels, C. reticulata peels, C. sinensis seeds, R. tinctorum seeds and L. inermis leaves were 62.04, 38.84, 43.60, 59.01 and 33.99 µl/ml, respectively. Also, all extracts showed the greatest mortality effect in 80 µl/ml concentration. According to these results, these plant extracts may use as herbal pesticides chemical control programme of common pistachio psylla.     

Demographic parameters of wrinkling aphid of pistachio leaf, Forda hirsuta Mordv. (Hem.:Pemphigidae) insitu of Rafsanjan's orchards

Wrinkling aphid of pistachio leaf, Forda hirsuta Mordv. (Hem.:Pemphigidae) is one of the pests of pistachio trees. This aphid caused the shrinkage, thickening, and changing the color of the pistachio leaves. Since insect feeds from leave edges, the thick and rolled upward wrinkles were formed, which its green color turned into red. Therefore, its economical damages are out of direct feeding from plant extraction, twisting pistachio leaves, and the decrease of photosynthesis. In this research two orchards and 10 trees that each of them were selected in Rafsanjan region and 58 fundatrix galls, 120 nymphal galls were marked and the demographic parameters for apterus parthenogenesis female of this aphid were calculated via daily observations. The results indicated that intrinsic rates of increase (r) for 1, 2 and 3 generations were 0.01, 0.0638 and 0.0575 femal/femal/days respectively, Doubling time (DT) were 69.31, 10.52 and 12.04 days, respectively, net fecundity rates were 1.71, 11.5 and 7.37 femal/femal/days, respectively, Net fertility rates were 1.11, 8.87 and 5.01 days, respectively, and mean generation times (Tc) were calculated to be 31.5, 32.2 and 31.87 days, respectively. Other reproductive parameters such as gross hatch rate, gross fecundity rate, gross fertility rate, mean age gross fecundity and fertility, mean age net fecundity and fertility, mean age hatch, finite rate of increase (lambda), intrinsic birth rate (b) intrinsic death rate (d) and daily reproductive rate were also calculated. The results revealed that population parameters especially r in the first and second generations were lowest and highest, respectively and mean longevity of fundatrix was 30 days and the born nymphs made separate galls in the edge of pistachio leaves.     

Hexamethylenebisacetamide modulation of thyroglobulin and protein levels in thyroid cells is not mediated by phosphatidylinositol-3-kinase: a study with wortmannin

Hexamethylenebisacetamide (HMBA) induces in murine erythroleukemia cells (MELC) the commitment to terminal differentiation leading to globin gene expression. In the thyroid, HMBA acts as a growth factor and also as a differentiating agent. In the present paper, we studied the effect of HMBA on the very specific thyroid marker thyroglobulin (Tg) in two different thyroid cell systems, i.e., porcine cells in primary culture and ovine cells in long term culture. Using wortmannin, a specific inhibitor of phosphatidylinositol-3-kinase, we investigated whether this enzyme is involved in HMBA mode of action. We found that HMBA is a positive modulator of Tg production in porcine cells, but a negative effector in the OVNIS cell line. As all HMBA effects studied in the present paper, i.e., Tg production and total protein levels, are not inhibited by wortmannin, we suggest the non-involvement of phosphatidylinositol-3-kinase in HMBA mode of action.     

Comparative study on biological parameters of Bemisia tabaci (Genn.) collected on four host plants from Varamin-Iran

During 2003 biological parameters of sweetpotato whitefly, B. tabaci (Genn.) (Horn. Aleyrodidae) as a major pest of field crops, vegetables and ornamentals were studied. In this study, the infested leaves of cucumber (Cucumis sativus L.) zucchini (Cucurbita pepo L.) eggplant (Solanum melongena L.) and cotton (Gossypium hirsutum L.) with whitefly nymphs and pupae were collected from Varamin-Iran, and were transferred to the laboratory. The newly emerged males and females of each population were released separately into a large cage set on cotton plants. Experiments were carried out in a growth chamber on cotton, (Varamin 76 variety) at 24+/-2 degrees C, 55+/-3% RH and 16:8 h (L: D) photoperiod. The adults of every collected population after emergency were reared in the large cages (40 x 50 x 70) containing pots of cotton plant. The preimaginal developmental time and reproductive parameters of 40 mated females were calculated for each population. The results revealed that the intrinsic rates of increase (r(m)), on cucumber, zucchini, eggplant and cotton were 0.093, 0.068, 0.085 and 0.078 respectively, gross fertility rate, were 67.92, 59.08, 76.13 and 63.14 respectively and mean generation time (T(c)) were 27.4, 27.74, 27.73 and 27.52 days respectively. Other demographic parameters such as intrinsic birth rate (b), intrinsic death rate (d), finite rate of increase (lambda), doubling time (DT), net fecundity rate, net fertility rate , gross fecundity rate, mean age gross fecundity and fertility, mean age net fecundity and fertility, mean age hatch, number of eggs/female/day and daily reproductive rate were also calculated. The results revealed that there were not significant differences between parameters of demography in different populations and the host plant has no significant influence on biological parameters.     

Characterization of Angiotensin-Converting Enzyme 2 Ectodomain Shedding from Mouse Proximal Tubular Cells

Angiotensin-converting enzyme 2 (ACE2) is highly expressed in the kidney proximal tubule, where it cleaves angiotensin (Ang) II to Ang-(1-7). Urinary ACE2 levels increase in diabetes, suggesting that ACE2 may be shed from tubular cells. The aim of this study was to determine if ACE2 is shed from proximal tubular cells, to characterize ACE2 fragments, and to study pathways for shedding. Studies involved primary cultures of mouse proximal tubular cells, with ACE2 activity measured using a synthetic substrate, and analysis of ACE2 fragments by immunoblots and mass spectrometry. The culture media from mouse proximal tubular cells demonstrated a time-dependent increase in ACE2 activity, suggesting constitutive ACE2 shedding. ACE2 was detected in media as two bands at ∼90 kDa and ∼70 kDa on immunoblots. By contrast, full-length ACE2 appeared at ∼100 kDa in cell lysates or mouse kidney cortex. Mass spectrometry of the two deglycosylated fragments identified peptides matching mouse ACE2 at positions 18-706 and 18-577, respectively. The C-terminus of the 18-706 peptide fragment contained a non-tryptic site, suggesting that Met⁷⁰⁶ is a candidate ACE2 cleavage site. Incubation of cells in high D-glucose (25 mM) (and to a lesser extent Ang II) for 48–72 h increased ACE2 activity in the media (p<0.001), an effect blocked by inhibition of a disintegrin and metalloproteinase (ADAM)17. High D-glucose increased ADAM17 activity in cell lysates (p<0.05). These data indicate that two glycosylated ACE2 fragments are constitutively shed from mouse proximal tubular cells. ACE2 shedding is stimulated by high D-glucose, at least partly via an ADAM17-mediated pathway. The results suggest that proximal tubular shedding of ACE2 may increase in diabetes, which could enhance degradation of Ang II in the tubular lumen, and increase levels of Ang-(1-7).     

Uridine and the Control of Phototropism in Oat (Avena sativa L.) Coleoptiles

The short-term growth response of oat (Avena sativa L.) coleoptiles to exogenously applied uridine was studied both in excised apical segments and in the intact seedlings. In both cases growth of coleoptile tissue was inhibited by uridine. The inhibition of coleoptile growth consistently occurred 20–30 min after uridine treatment, which is within the lag period of their phototropic response. Asymmetric application of uridine to coleoptiles in the intact seedlings resulted in their bending toward the direction to which uridine was applied in the absence of light stimulus. These findings suggest that uridine or its metabolites, plays an important role in the phototropism of oat coleoptiles and provide support to the Bruinsma–Hasegawa theory as an alternative to the Cholodny–Went theory for explaining phototropism.     

Effects of ethylene and inhibitors of ethylene synthesis and action on nodulation in common bean (Phaseolus vulgaris L.)

The ethylene releasing compound, 2-chloroethylphosphonic acid (ethephon) inhibited nodule development in common bean (Phaseolus vulgaris L.) plants. In contrast, inhibitors of ethylene synthesis or its physiological activity enhanced nodulation. In a co-culture of bean seeds and rhizobia, ethephon inhibited rhizobial growth while inhibitors of ethylene synthesis or action did not influence the growth and proliferation of rhizobia. These data emphasize the role of ethylene as a regulator of nodulation in determinate nodulators and indicate that the ethylene signaling pathway involved in the nodulation process is not limited to the plant host but also involves the bacterial symbiont.     

Study on the physiology of diapause, cold hardiness and supercooling point of overwintering pupae of the pistachio fruit hull borer, Arimania comaroffi

The pistachio fruit hull borer, Arimania comaroffi (Ragonot) (Lepidoptera: Pyralidae), is a key pest of pistachio orchards in Iran. This pest passes the winter as diapausing pupae. In this study, some physiological changes in relation to environmental temperature were investigated in field collected pupae. The relationship between supercooling point, cold hardiness and physiological changes of a wild population of this pest was also investigated. The glycogen content decreased with decrease in environmental temperature. Decrease in glycogen content was proportional to increase in total body sugar, trehalose, myo-inositol and sorbitol contents. In January with mean ambient temperature of 5.4°C, glycogen (5 mg/g fresh body weight) content was at the lowest level whereas total body sugar (10.3 mg/g fresh body weight), trehalose (8.6 mg/g fresh body weight), myo-inositol (5.3 mg/g fresh body weight) and sorbitol (2.6 mg/g fresh body weight) were at the highest levels. Total body sugar, trehalose, myo-inositol and sorbitol contents increased as mean temperature decreased from 22.7°C in October to 5.4°C in January. Total body lipid decreased during overwintering and reached to the lowest level at the end of March. Supercooling points were decreased from October to January and reached to the lowest level (-16°C) in January with minimum ambient temperature of -10°C. Survival at low temperature after 24 h was also greatest in January with 72% survival at -10°C, 39% survival at -15°C and 0% survival at -20°C. Increase in temperature from February onward, was proportional with increase in supercooling points and decrease in survival rate. Regardless of sampling date, all pupae died after 24 h at -20°C, whereas none pupae died after 24 h at -5°C. This indicates that this insect is freeze-intolerant.     

Life table attributes of Clitostethus arcuatus (Coleoptera: Coccinellidae) feeding on Trialeurodes vaporariorum and Siphoninus phillyreae (Hemiptera: Aleyrodidae)

The ladybird beetle Clitostethus arcuatus Rossi (Coleoptera: Coccinellidae) is one of the most effective predators of the greenhouse whitefly, Trialeurodes vaporariorum Westwood, and the ash whitefly, Siphoninus phillyreae Haliday (Hem: Aleyrodidae). Two stock cultures of C. arcuatus were established under controlled conditions (25 ± 2 °C, 65 ± 5%RH and L–D:16–8), one using T. vaporariorum and one using S. phillyreae as prey. Newly laid C. arcuatus eggs from each culture were evaluated for immature survival. Thirty pairs of C. arcuatus (24 h-old) were selected for studying the reproductive life history of C. arcuatus on the two hosts. Results showed that the period between oviposition and hatch did not show significant difference on different prey. Duration of different instars stages of C. arcuatus differed significantly, except second instars, which was 4 days for both diets. Pupal period differed significantly between the two prey types. Egg hatch was 95% and 91.7% for adults fed on T. vaporariorum and S. phillyreae, respectively. There was a significant difference among some treatments for gross fecundity rate and net reproductive rate (R₀), indicating that prey had a significant impact on the biological activities of C. arcuatus. The intrinsic rate (r_m) and finite rate of increase (λ) were 0.063 and 0.078, respectively, for T. vaporariorum, and 1.0026 and, 1.08, respectively, for S. phillyreae.