Effect of grass density and date of tapping on Acacia senegal gum yield in north kordofan state, Sudan

We conducted a two-factor experiment in randomized com- plete block design with four replications during 2004 in El Demokeya Forest Reserve and El Himaira Natural Forest, North Kordofan State, Sudan. The objective was to develop an understanding of the ecological effects of under-story vegetation and tapping date on the productivity of gum arabic from Acacia senegal as over story cover. The first factor was grass cover which was tested in four levels (100% and 50% grass cover in addition to bare and burnt). The second factor, date of tapping was tested in three levels namely (1st Oct, 15th Oct and 1st Nov). The first picking was done after 45 days from tapping and the gum yield up to seven pickings was collected at intervals of 15 days. Gum yield from each picking was collected and weighed using sensitive balance. Analysis of variance was carried out using MSTAT-C statistical package, and the Tukey test was applied for mean comparisons. The results showed highly significant differences (p<0.01) of grass cover on gum arabic yield in the two sites for most of the first consecutive pickings (1st-4th out of seven) in addition to total yield (kg/ha). With exception to the 4th pickings, the interaction effect between the grass densities and tapping date was not significantly different. The total gum yield was significantly (p<0.05) increased in only two pickings (third and fourth) in El Demokeya Forest Reserve and two pickings (1st and 2nd) at El Himaira Natural Forest. The density of grass cover significantly (p<0.05) affected the number of pickings at both sites; the number of gum pickings was directly proportional to grass density. The number of gum pickings was found to be significantly (p < 0.05) increased at the early date of tapping.     

Maternal influence on diapause induction: an approach to improve long-term storage of <Emphasis Type="Italic">Trichogramma chilonis</Emphasis>

We have investigated the role of the thermo-photoperiodic condition of maternal generation in diapause induction of Trichogramma chilonis (Ishii) (Hymenoptera: Trichogrammatidae) lab strain. To test the maternal effect, two lines of T. chilonis lab strain were generated by rearing them for one generation at: (1) 15 °C with L:D-12:12 (¹⁵F-1₁₂) and (2) 15 °C with L:D-20:4 (¹⁵F-1₂₀). The laboratory strain reared at 15 °C with L:D-12:12 for 65 generations (¹⁵F-65₁₂) was used as the control (acclimatized strain) due to its proven diapausing capacity. The ¹⁵F-1₂₀ line failed to undergo diapause, though healthy pre-pupae were formed at the pre-storage condition (at 10 °C with L:D- 8:16 and RH-60-70%). However, ¹⁵F-1₁₂ line could successfully complete all the phases of diapause and was comparable with the control batch. Considering 50% adult emergence and minimum 3 days of longevity, 125 days of storage could be achieved. From our current study, we conclude that diapause can be induced in T. chilonis lab strain by providing appropriate thermo-photoperiod to their maternal generation (for a single generation) followed by suitable diapause inducing and terminating protocols.     

家蚕与不同品种桑树之间的脂质代谢关系（摘要）

[目的]探讨家蚕与其寄主植物体内脂质代谢的相互关系,为研究桑叶中营养物质含量对家蚕生长发育的影响提供参考。[方法]以家蚕品种NB4D2以及V-1、S-36、M-5 3种桑树品种的嫩叶、半成熟叶、成熟叶为研究对象;利用气液色谱法对桑叶中以及家蚕体内总脂以及脂肪酸含量进行分析;采用方差分析和多重比较方法进行数据处理。[结果]桑树嫩叶中油脂含量高于半成熟叶和成熟叶;嫩叶中脂肪酸前体含量较高,半成熟叶中不饱和脂肪酸含量较高,成熟叶中饱和脂肪酸含量较高;V-1桑树品种的叶面油脂含量高于S-36和M-5品种;V-1和S-36叶片中不饱和脂肪酸含量较高,M-5叶片中饱和脂肪酸含量较高;在蚕的血淋巴中没有发现月桂酸,但在其排泄物中含量较高;取食M-5叶片的蚕幼虫的血淋巴中棕榈酸和硬脂酸含量较高,而取食S-36和V-1叶片的蚕幼虫的血淋巴中亚油酸和亚麻酸含量较高,但桑树叶片中油酸和亚油酸比例是相互交替的;M-5叶片中油酸和亚油酸所占比例分别为1.93%和16.8%,而取食该品种叶片的蚕幼虫血淋巴中油酸和亚油酸所占比例则分别为21.5%和6.95%;取食S-36和V-1叶片的蚕幼虫血淋巴中油酸和亚油酸含量变化也有类似的转变。[结论]家蚕血淋巴、排泄物中油脂及脂肪酸的含量与桑树的品种及桑叶的成熟度密切相关,该研究结果对家蚕的育种与繁殖具有重要的指导意义。     

A HPTLC densitometric method for the determination of aloeverose in Aloe vera gel

Aloe vera gel is a familiar ingredient in a range of widely available and advertisement healthcare and cosmetic products. As to date there are no documented reports on the standardization of A. vera gel and the following study is an attempt in this direction. A. vera gel was evaluated for its aloeverose content for the first time. Aloeverose, was separated on a thin-layer of silica gel by isocratic gradient elution technique was determined by using HPTLC-photodensitometry. The proposed method is simple and sensitive and can be used for the routine assay of aloeverose in phytomedicines containing A. vera gel.     

Gum arabic yield in differently managed <Emphasis Type="Italic">Acacia senegal</Emphasis> stands in western Sudan

A comparative study of gum arabic yield trends per tree and picking in relation to stand management (by farmers and by researchers) and type (natural and planted) was conducted at two locations in North Kordofan, Sudan, for a three-year period. In addition, eight-year yield trends in relation to rainfall were compared based on the 1993–2000 gum yield data from 1440 trees. Although the gum arabic yield followed the same trend over time in all stands at both locations, the gum yield from farm stands, whether planted or natural, was 47% to 60% lower than that from research stands. Late tapping reduced the gum yield by 40% and 50% at the two different locations, respectively. Yield was highly affected by rainfall, correlating positively with annual rainfall in six of the eight years of the study. These findings can be used for improving gum arabic yield through management interventions and for predicting yield in relation to stand type, management regime and rainfall.     

Functional response of <Emphasis Type="Italic">Geocoris ochropterus</Emphasis> Fieber (Hemiptera: Geocoridae) to different egg densities of <Emphasis Type="Italic">Helicoverpa armigera</Emphasis> (Hübner) (Lepidoptera: Noctuidae)

The biology and predatory efficiency of Geocoris ochropterus Fieber (Hemiptera: Geocoridae) has been studied extensively against many insect pests, but information on functional response of different stages of G. ochropterus to Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) is lacking so far. The functional response of different stages of G. ochropterus to varying densities of eggs of H. armigera was investigated in the laboratory at 26?±?2°C, 65?±?2% RH and 12 L: 12D. Immature stages i.e. 3rd, 4th, 5th instar and adult predator exhibited type II functional response. Handling time decreased with increasing predator’s developmental stage. Adult G. ochropterus followed by fifth instar exhibited highest egg consumption and attack rate compared to other stages. Functional response parameters indicate that the adult and fifth instar of G. ochropterus were more voracious and efficient than other juveniles and might be useful as promising biocontrol agent against H. armigera.