Investigation on some biological aspects of Chrysoperla lucasina (Chrysopidae: Neuroptera) on Bemisia tabaci in laboratory conditions.

Bemisia tabaci is one of the most important key pests of many types of cultivated plants. Lacewings (Chrysopidae: Neuroptera) are predatory insects, widely used in biological control programs. Between them green lacewing is a promising biological control agent of pests in green houses and crop fields. In this study, gravid females of the green lacewing Chrysoperla lucasina (Lacroix) were captured from Sarepolzahab ( altitude 540m, latitude 34 degrees ,14' N 46 degrees, 9' E) in western part of Iran. Collected insects were reared in a growth chamber, under experimental conditions (25 +/- 1 degrees C, 70 +/- 5% RH and a photoperiod of 16:8 L: D). Different diets were offered to larvae which consisted of a whitefly species B. tabaci, an aphid Myzus persica and also lyophilized powder of drone honeybee (Apis melifera). As different foods were used to nurish larvae, so for each diet, mean larval period were calculated, and finally means were compared to each other. Anova in MSTAT-C was used for analysis of variance, and Duncan multiple range test (DMRT) to compare between means. The results showed that larvae had maximum duration of 27 +/- 0.33 days when fed on honeybee lyophilized powder and the minimum value was 17.9 +/- 0.3 days for B. tabaci. 25 +/- 0.27 day recorded for M. persicae. Food preference of the 3rd instar larvae of green lacewing was surveyed, they showed a food preference to M. persicae, to compare with B. tabaci, as the former has a bigger body size, so more easily to be captured by the predator larvae. The 3rd instar larvae of lacewing were more voracious on preys, than the 1st or the 2nd instar larvae. Statistically speaking, there were a significantly difference when mean of different preys consumed by predator larvae were compared. We found, that when the predator larvae have fed on B. tabaci, their development time was shorter, and when arrived to adult stage, the adults showed, an improved fertility. The results indicated that the suitable prey not only can increase the rate of through accelerating developmental stages of the predator and by means of an increase in its pupal body weight consequently promoting the fecundity of resulting adults, but also can alter predators population density in relation to own production numbers.

Study of interaction between plant nutrition (N,P,K and Ca) and verticillios wilt disease (Verticillium dahliae) in cucumber.

Cucumber wilt disease caused by verticillium dahliae is one of the most important diseases of cucumber. Disease severity can to be decreased by plant nutrition management, especially nitrogen, phosphorus, potassium and calcium levels. For this purpose, interaction between plant nutrition and cucumber verticillios disease in cucumber was studied. Different levels of N, P, K and Ca on one current cultivar of cucumber were investigated at the presence and absence of fungus, using a factorial analysis based on completely randomized design with three replications. Significant different were observed among the different levels of elements used in this study. Presence of N, P, K and Ca increased the percentage of alive plants in comparison with control (distilled water + fungus). The effects of different levels of N, P, K and Ca were also investigated on growth of V. dahliae in vitro at a complete randomized design with three replications. Variance analysis of growth area of the fungus showed significant difference among some levels of the elements. The highest area growth of fungus was occurred at 0.1 gr/l of KNO3 and was 47/26 Cm2. The factors investigated, clearly suggested the occurrence of a wide interaction between cucumber nutrition (N, P, K and Ca) and V.dahliae and showed the importance of plant nutrituin management for decrease of disease severity.

Altered levels of hypothalamic-pituitary-adrenocortical axis hormones in baboons and mice during the course of infection with Schistosoma mansoni.

Baboons with primary or secondary exposure to Schistosoma mansoni were compared with each other over a 12-week infection period and with baseline values obtained from uninfected baboons with respect to serum levels of the hypothalamic-pituitary-adrenal (HPA) axis hormones-corticotropin-releasing hormone, adrenocorticotropic hormone, dehydroepiandrosterone sulfate (DHEA-S), and cortisol. Baboons with primary infections, when worm recovery and oviposition rates were high and hepatic schistosome egg granulomas were large, had decreasing levels of these hormones as infection progressed, compared with both uninfected and reexposed baboons. The most reduced hormone level was that of DHEA-S. Reduction of DHEA-S and cortisol levels also occurred in primary murine infections. Reexposed baboons with low worm recovery and oviposition rates and small (modulated) hepatic granulomas showed the opposite pattern: HPA axis hormone levels were maintained at, or exceeded, the baseline values of uninfected baboons. These results suggest that HPA axis hormones may play a role in regulating the establishment, maturation, and oviposition of schistosomes and the progression of schistosomiasis.

Silicon ribbon growth using scanned lasers.

The recent drive for low-cost photovoltaic arrays has renewed the interest in growing silicon in ribbon form. Our approach is to use a pair of scanned focused CO(2) laser beams to establish a molten zone in a preformed fine-grained polycrystalline ribbon. Large-grained macrocrystalline silicon is then drawn from the molten zone at high rates. The coupling of the 10.6-microm laser beam to the melt zone is very low due to the high reflectivity of molten silicon. However, the coupling can be greatly increased by using a spherical-section reflector to reimage the reflected beam onto the molten zone. Silicon ribbon has been grown at rates up to 13.3 cm/min by this method. The best solar cell fabricated so far on this material had a conversion efficiency of 12.7%.