Search

Recently, tomato leaf miner (TLM) Tuta absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae), is the most notorious pest of tomato worldwide causing severe reduction of yields in both protected and open fields. In Sudan, the pest was recorded to attack all tomato cultivation areas causing considerable damage affecting income of poor farmers. Various pesticides of different active ingredients are applied excessively and routinely to control T. absoluta in tomato. As known, reliance on insecticide cause adverse impacts in human health, create insect resistance as well as affect environment and natural enemies. This study is initiated to evaluate the efficacy of extracts of 3 botanicals as alternative to synthetic insecticides against T. absoluta. A randomized Complete Block Design field experiment was conducted at Takroof experimental farm of Kassala and Gash Research Station, Sudan during season (2019/2020). The experiment consisted of Neem seed oil, water extracts of Datura, Water extract of Vinca, Dancid®; synthetic insecticide as standard, and non-treated treatment as control. Each treatment was replicated thrice Data included number of infested plants/plot, number of mines/plot, percentage of infested fruits and yield (Ton/ha) were compiled, variance among treatments (ANOVA) was statistically analyzed and means were separated using Duncan Multiple Range Test (DMRT) applying SAS 9 a computer based program. The results of this study, revealed high significant difference between treatments in the number of infested plants/plot, number of active mines/plots for the three assessment times of the post spray counts. Water extract of Datura and Neem seed oil were better than Dancid® and Vinca in reducing the number of infested plants/plots and number of active mines/plots. All test products were significantly same in reduction the percentage of infestation of fruits and they were less than the control. Also high significant difference was observed between treatments on yield. Plots treated with Neem seed oil obtained the highest yield followed by WE of Datura, Dancid®, WE of Vinca with 11.2, 9.9, 9.7, 8.8 (Tons/ha) while the un-treated plots obtained the lowest yield (3.8 Tons/ ha). For their potency, cheapness, easy processing and environmental friendly characters, Neem seed oil, WE of Datura, and WE of Vinca are recommended to be used to control T. absoluta in tomato crop. Keywords: Tuta absoluta neem seed oil, Datura, periwinkle, aqueous extracts

A field experiment was conducted at Kassala and Gash Research Station farm, Kassala, Sudan for three consecutive seasons to evaluate resistance of 16 tomato entries to tomato fruit borer Tuta absoluta (Meyrick,1917) (Lepidoptera: Gelechiidae). The entries consisted of 12 Sudanese local tomato accessions compared to 4 hybrids widely cultivated in Sudan. The experiment was arranged in a randomized complete block design with three replicates following the cultural practices recommended by the Agricultural Research Corporation of Sudan. Parameters of interaction of the pest with plant included number of active mines/plant, percentage of infested plants/ plot, percentage of infested fruits (%) were assessed and used as indicators for resistance to tomato fruit borer while plant characters including days to 50 % flowering, fruit diameter (cm), total soluble solids (TSS), density of trichomes/cm2 (DT), chemical constituents and yield (ton/ ha) were assessed and their role in resistance was determined and discussed using Pearson correlation. The interaction of the pest with tomato entries revealed high significant differences between entries (pr > f 2 of leaf, yield of tomato (Ton/Ha) and content of Lycopene, Tannin, Carotene and Ascorbic acid. Tomato accessions HSD11429, HSD6071 and HSD14358 recorded the least percentage of infested leaves/plot, least number of active mines/plot and least percentage of infested fruits/plot while the same accessions were obtained the highest fruit diameters (cm), highest density of trichomes/cm2 of leaves, highest TSS as well as highest yield (Ton/Ha). Accession HSD14358 obtained the highest content of Tannin followed by HSD11429 and HSD6069. Highly negative correlation was observed between the number of trichomes in cm2 of leaves and the percentage of infested plants/plot (-0.8749, T. absoluta as well as obtained highest yield among other entries. The mechanism of resistance can be attributed to the density of trichomes, high content of TSS and appropriate percentage of Tannin. According to their resistance characters and yield performance authors would like to recommend the use of the three elite accessions as source of resistance to T. absoluta.

The objective of this study was to evaluate the effectiveness of endophagous Encyrtid parasitic wasp Aenasiusarizonensis (Girault) (Hymenoptera, Chalcidoidea), as a natural enemy for controlling the Mealybug, Phenacoccussolenopsis Tinsley (Hemiptera: Pseudococcidae). Where a Randomized Complete Block Design (RCBD) was adopted. Both, field survey and Laboratory experiments were conducted to study some biological characteristics of the parasitoid A. arizonensis. The results of field study revealed that, the parasitioid was available most of the year, and was highly effective on adults and last larval instar of the mealy bug, P. Solenopsis, with a total percentage of parasitism of 31.26%. While the laboratory results showed that, the duration from oviposition to adult emergence were similar for both male and female. Longevity of male was 23± 2.33 days and female 23.37±1.89 days. Mean daily fecundity in terms of number of Parasitized hosts /female / day ranged from 20 to 24. The sex ratio was 1:1.6 for the male and female in the progeny. Generally, a mass rearing of this parasitoid, with a conservation and augmentation releases could help in the application of an effective management strategy for the control of the cotton mealy bug in the field.

Cotton mealybug (Phenacoccussolenopsis) is a serious devastating pest which goes on a wide array of plant families. The pest spread all over the world from cool to dry hot regions. The main objective of this study was to investigate the food preference and behavior of P. solenopsis Tinseley (Hemiptera:Pseudococcidae) towards selected host plants in Khartoum State, Sudan, where a multi-choice experiment under laboratory conditions was adopted. Eight plant species were screened for attractiveness and food preference to Cotton mealybug. Where the proportions of the 1st, 2nd and 3rd nymphal instars and the adult females were recorded at 2, 8 and 24 hours after release, and compared with Chinese rose (Rosa chinensis) the control. The result revealed that the proportions of the 1st, 2nd and 3rd nymphal instars and adult females were maximum on plants of family Malvaceae, particularly the Okra (Hibiscus esculentus) followed by Cotton (Gossypium sp.) and Hambouk (Abutilon pannosum) as compared with the control. However, in contrast, the proportions were very low on unpalatable plants like Zaleya (Locally known as Raba) (Zaleyapentandra) and Eggplant (Solanum melongenaL.). However, in contrast, the proportions were very low on unpalatable plants like Zaleya (Locally known as Raba) (Zaleya pentandra) and Eggplant (SolanummelongenaL.). In conclusion, the most favorable host plants of the Cotton mealybug belonging to the family Malvaceae, while the families of Solanaceae [Egg plant (SolanummelongenaL.)] and Aizoaceae (Raba) were found to be the least preferred host plants.

This study was conducted to investigate the influence of soil applications of argel (Solenostemma argel) dry leaves on flowering and yield of the dry date Barakawi cultivar in a completely randomized block design. Argel treatments were 0, 37.5 g once (1X1), 37.5 g twice (1X2), 37.5 g thrice (1X3), 75 g once (2X1) and 112.5 g once (3X1). Each treatment was replicated 5 times in two successive seasons under the conditions of the Northern State, Sudan. Argel treatments enhanced flowering and yield parameters of date palms and improved the physical characteristics of the fruits. As a nutritional role seems invalid due to the low amounts used, gains from argel leaves additives might owe to either a pesticide or a growth regulator-like effect.

Self-tolerance is mainly established through clonal deletion of autoreactive T cells during thymic differentiation. The mechanisms by which deletion is achieved are poorly understood. Here we use a specific polymerase chain reaction-based system to characterize DNA fragmentation and show that after in vivo treatment of neonatal mice with staphylococcus enterotoxin B, selective apoptosis of V beta 8+ thymocytes occurs. This process precedes detectable deletion of V beta 8+ cells as determined by phenotypic analysis. Moreover, in vivo administration of cycloheximide and, to a lesser extent, actinomycin D, inhibits apoptosis of staphylococcus enterotoxin B specific thymocytes. Thus, macromolecular synthesis is a requirement for negative selection.