Population dynamics of Oligonychus afrasiaticus in the southern Arava Valley of Israel in relation to date fruit characteristics and climatic conditions

1 Oligonychus afrasiaticus, the old world date mite, is a serious pest of dates in North Africa and the Near East, including Israel. It attacks and rapidly develops when the fruit is young and green. Mite phenology is affected by date cultivar, but the relationship between fruit characteristics and mite population development is unknown. 2 We report that mite establishment on the main cultivars grown in Israel, ‘Medjool’, ‘Barhi’ and ‘Deglet Noor’, began only when the water content of the fruit increased to ≥ 84%. Fruit bunch architecture and resistance to penetration, as well as sugar composition and content, were not key factors in mite establishment. 3 Later in the season, when total sugar levels reached ≥ 150 mg/g fresh fruit weight, total soluble solids comprised 15% and water content decreased to ≤ 75%, mite populations declined. 4 Yearly climatic variations could be responsible for phenological asynchrony between the pest and fruit development.     

Physiological parameters of salt tolerance during germination and seedling growth of Sorghum bicolor cultivars of the same subtropical origin

Salt-tolerant ecotypes (or cultivars, varieties, etc.) of different plant species have been long known to evolve in nature. In the past few years, plant breeders have made significant achievements regarding salt tolerance in a number of potential crops using artificial selection. The aim of this work was to evaluate and screening of the natural sea water (Red sea) tolerance of 7 Saudi local (Baish, Jazan; 17.388086, 42.524070) cultivars of sorghum (Sorghumbicolor L., Moench; Poaceae) with respect to the performance of some physiological parameters such as germination, shoot and root development which could be recommended to local farmers and plant breeders. The shoot growth of the studied sorghum cultivars were significantly affected by the exposure to sea water. Root growth was different among cultivars even when treated with normal water. The cultivar C3 (mix white and red seeds) was observed as more salt tolerant and cultivar C4 (whitish seeds) was more salt sensitive on the basis of the germination-ability and shoot development. Cultivar C3 was also observed to produce better seeds compared with the other cultivars. Results of this experiment can be useful to the local sorghum growing farmers or as a genetic resource for the development of sorghum cultivars with improved germination under salt stress.     

Effects of irradiance and spectral quality on seedling development of two Southeast Asian Hopea species

 Seedling developmental responses to understory shade combine the effects of reductions in irradiance and changes in spectral quality. We studied the seedling development of two Southeast Asian dipterocarp trees in response to differences in irradiance (photosynthetic photon flux density, PPFD) and spectral quality (red to far-red ratio, R:FR). The two species, Hopea helferei and H. odorata, are taxonomically closely related but differ in their ecological requirements; H. helferei is more drought-tolerant and typically grows in more open habitats. Seedlings were grown in six different replicated shadehouse treatments varying in percentage of solar PPFD and R:FR. The two species differed in the influence of light variables on most seedling characters, particularly for final height, internode distance, branch/trunk internodes, stem length/mass, leaf area/stem length, petiole length, and growth/mol of photons received. Most of the characters in both taxa were primarily influenced by PPFD, but spectral quality also influenced some characters – more so for H. odorata. The latter species grew more rapidly, particularly in the low PPFD treatments, and its leaves were capable of higher photosynthesis rates. However, growth in H. helferei was not reduced in direct sunlight. The growth of this taxon may be constrained by adaptations, particularly in leaves, for drought tolerance. Received: 14 April 1996 / Accepted: 8 October 1996     

Desiccation tolerance in red and green gametophytes of Jamesoniella colorata in relation to photoprotection

This study tests the hypothesis that red-leaved gametophytes of the liverwort Jamesoniella colorata (Lehm.) Schiffn., which are found in relatively dry habitats, are more desiccation tolerant than their green counterparts, which are found in moister environments, through superior photoprotective systems. The potential role of red foliar pigments in relation to water deficits is investigated by measuring cell water-relations, oxidative damage and photosynthetic responses. The presence of red pigments, or other cellular constituents, did not affect cell water-relations during dehydration and thus appear not to be involved in cell osmotic regulation. During drying, both colour morphs showed a similar non-photochemical quenching activity and did not experience significant oxidative damage, as measured by the amounts of ascorbate, malondialdehyde and photosynthetic pigments. However, the levels of oxidative damage increased directly upon rewetting the gametophytes, especially in low light conditions (25 μmol m⁻² s⁻¹). The efficiency of photosystem II only recovered partially after severe water deficits in both phenotypes. However, the red gametophytes recovered faster and more completely from mild water deficits than did the greens. Moreover, they experienced significantly less photobleaching after rehydration in low light. It is suggested that red pigments and/or carotenoids in these gametophytes improve desiccation tolerance by alleviating photooxidative damage.     

A population genetic study of the Banks and Torres Islands (Vanuatu) and of the Santa Cruz Islands and polynesian outliers (Solomon Islands)

As part of a multidisciplinary survey of populations in the Banks and Torres Islands of Vanuatu and the Southern and Central Districts of the Solomon Islands, nearly 2,400 persons have been tested for ABO blood groups and a number of serum protein and red cell enzyme genetic marker systems. For the ABO system, the populations are characterized in general by high gene O and low gene B frequencies except in two of the Polynesian Outlier Islands, Rennell and Bellona, which have high frequencies of B. Among the serum proteins, several alleles have distributions indicating significant movement of people between islands. These include Albumin ^{New Guinea} and the transferrin alleles Tf, and Tf, and Tf. Similar specific alleles for red cell enzymes also show distributions reflecting interisland population movement as well as contact with persons from outside the southern Pacific region. Examples are ACP in the acid phosphatase system, PGM and PGM, PGM and PGM, PGK⁴ and also HbJ^Tongariki. The data available for 11 polymorphic systems were used to generate genetic distances. Of the four Polynesian Outlier Islands, Anuta is most remote genetically, with Rennell and Bellona also relatively isolated. The fourth Polynesian Outlier, Tikopia, occupies a position genetically close to the Melanesian populations of the Banks and Torres Islands and the southern Solomons. The history of early European contact and voyaging in the Pacific, as well as archaeological and linguistic evidence and local legends, indicate that significant movements of people occurred between islands and provided opportunities for genes to be introduced from Europeans, Africans, and Asians. The genetic marker studies give evidence for genes from all these sources, though at a low level. Despite this admixture, the Polynesian Outlier and Melanesian populations have preserved their own distinctive genetic patterns.     

PRODUCTION AND CELLULAR LOCALIZATION OF NEUTRAL LONG‐CHAIN LIPIDS IN THE HAPTOPHYTE ALGAE ISOCHRYSIS GALBANA AND EMILIANIA HUXLEYI1

Isochrysis galbana Parke, Emiliania huxleyi (Lohm.) Hay and Mohler, and some related prymnesiophyte algae produce as neutral lipids a set of polyunsaturated long‐chain (C_37–39) alkenones, alkenoates, and alkenes (PULCA). These biomarkers are widely used for paleothermometry, but the biosynthesis and cellular location of these unique lipids remain largely unknown. By staining with the fluorescent lipophilic dye Nile Red, we found that I. galbana and E. huxleyi, like many other algae, package their neutral lipid into cytoplasmic vesicles or lipid bodies. We found that these lipid bodies increase in abundance under nutrient limitation and disappear under prolonged darkness and show that this pattern correlates well with the concentration of PULCA as measured by TLC. In addition, we show that lipid vesicles purified by sucrose density gradient centrifugation consist predominantly of PULCA. We also found significant pools of neutral lipid associated with chloroplasts, and PULCA component profiles in lipid vesicles and chloroplasts are similar. Examination of cell ultrastructure shows conspicuous cytoplasmic and chloroplast lipid bodies, and we suggest that PULCA may be synthesized in chloroplasts and then exported to cytoplasmic lipid bodies for storage and eventual metabolism. Our results connect and extend prior observations of lipid bodies and membrane‐unbound PULCA in I. galbana and E. huxleyi, as well as the behavior of PULCA during nutrient and light stress.     

Steinernema diaprepesi n. sp. (Rhabditida: Steinernematidae), a Parasite of the Citrus Root Weevil Diaprepes abbreviatus (L) (Coleoptera: Curculionidae)

A nematode collected from Diaprepes abbreviatus is identified and described as a new species, Steinernema diaprepesi n. sp. The new species is closely related to S. feltiae, S. glaseri, and S. oregonense and can be distinguished from these species by the following characteristics: Males: Spicule averaging 79 (71-90) µm and spicule shape; D% (distance from anterior end to excretory pore/ esophagus length × 100) about 80; the ratio SW (spicule length/anal body width) about 1.8. Females: Vulva with short, double- flapped epiptygma; tail terminus usually with 5 papillae-like structures. Infective juveniles: Body averaging 1,002 (880-1,133) µm, EP (distance from anterior end to excretory pore) = 74 (66-83) µm; tail length = 83 (65-91) µm, and E% (EP/tail length × 100) = 89.6 (78-114). Lateral field pattern variable, the formula for the arrangement of ridges from head to tail is: 2, 6, 7, 8, 4, 2. The portion with eight ridges is the longest. This new species can be differentiated further from three closest species (S. feltiae, S. glaseri, and S. oregonense) by characteristic sequences of their ITS regions, including sequence lengths, ratios of similarity, composition, and differences in base characters in sequence alignment.     

暗腹雪鸡与海兰褐鸡血液生理生化指标的比较

为了解暗腹雪鸡（Tetraogallus himalayensis）正常血液生理生化特性,本文对暗腹雪鸡21项血液生理生化指标进行了测定,并与海兰褐鸡（Gallus gallus domesticus var. Hyline）进行了比较。测定结果,暗腹雪鸡的红细胞纵径及横纵径乘积、平均红细胞容积及平均红细胞血红蛋白含量极显著大于海兰褐鸡（P<0.01）;暗腹雪鸡天冬氨酸氨基转移酶和胆固醇含量均极显著高于海兰褐鸡（P<0.01）。其他各项血液生理生化指标两禽种间之间差异不显著。实验结果表明,暗腹雪鸡血液生理生化指标与家养蛋鸡之间有一定差异,暗腹雪鸡对高原低氧环境有较强的适应性可能与其红细胞体积较大、平均红细胞容积及平均红细胞血红蛋白含量较高有一定关系。