Spatial mapping of gene expression in the salivary glands of the dengue vector mosquito, aedes aegypti

<p>Abstract</p> <p>Background</p> <p><it>Aedes aegypti </it>mosquitoes are the main vectors of dengue viruses to humans. Understanding their biology and interactions with the pathogen are prerequisites for development of dengue transmission control strategies. Mosquito salivary glands are organs involved directly in pathogen transmission to vertebrate hosts. Information on the spatial distribution of gene expression in these organs is expected to assist in the development of novel disease control strategies, including those that entail the release of transgenic mosquitoes with impaired vector competence.</p> <p>Results</p> <p>We report here the hybridization <it>in situ </it>patterns of 30 transcripts expressed in the salivary glands of adult <it>Ae. aegypti </it>females. Distinct spatial accumulation patterns were identified. The products of twelve genes are localized exclusively in the proximal-lateral lobes. Among these, three accumulate preferentially in the most anterior portion of the proximal-lateral lobe. This pattern revealed a salivary gland cell type previously undescribed in <it>Ae. aegypti</it>, which was validated by transmission electron microscopy. Five distinct gene products accumulate in the distal-lateral lobes and another five localize in the medial lobe. Seven transcripts are found in the distal-lateral and medial lobes. The transcriptional product of one gene accumulates in proximal- and distal-lateral lobes. Seven genes analyzed by quantitative PCR are expressed constitutively. The most abundant salivary gland transcripts are those localized within the proximal-lateral lobes, while previous work has shown that the distal-lateral lobes are the most active in protein synthesis. This incongruity suggests a role for translational regulation in mosquito saliva production.</p> <p>Conclusions</p> <p>Transgenic mosquitoes with reduced vector competence have been proposed as tools for the control of dengue virus transmission. Expression of anti-dengue effector molecules in the distal-lateral lobes of <it>Ae. aegypti </it>salivary glands has been shown to reduce prevalence and mean intensities of viral infection. We anticipate greater efficiency of viral suppression if effector genes are expressed in all lobes of the salivary glands. Based on our data, a minimum of two promoters is necessary to drive the expression of one or more anti-dengue genes in all cells of the female salivary glands.</p

Assessment of resistant varieties of maize against Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) in laboratory conditions

Grains of five different maize varieties (MMRI Yellow, Pearl White, Malka-2016, YH-1898 and Sadaf) were evaluated for their comparative resistance to Tribolium castaneum under laboratory conditions (30+2°C and 70+5 R.H). Data of percent mortality were taken after 30, 60 and 90 days. Significantly, the maximum mortality of adults was observed in MMRI Yellow (28.57%, 33.67% and 41.61%) in sound seeds and lowest mortality was noted in Sadaf (14.88, 21.33% and 24.99%) during observation period. The seed germination was highest in MMRI Yellow which was 90% while lowest was noted in Sadaf as 50%. The highest protein contents were recorded in Malka-2016 (12.83% and 11.60%) and lowest in YH-1898 (3.90% and 2.50%) in both sound and cracked seeds. However, maximum fiber contents were observed in Malka-2106 (2.76% and 2.16%), while lowest (0.43% and 0.30%) in YH-1898 for both seed types. Consequently, MMRI Yellow variety was proved to be resistance as compared to other varieties with maximum germination. It can be concluded that resistant varieties of maize could be utilized in breeding program to reduce the post-harvest losses of grains

Insect Pest Complex of Wheat Crop

Wheat Triticum aestivum L. is grown on broad range of climatic conditions because of edible grains, cereal crop and stable food of about 2 Billion peoples worldwide. Additionally, it is the rich source of carbohydrates (55–60%), vegetable proteins and contributed 50–60% daily dietary requirement in Pakistan. Globally, wheat crops is grown over 90% area of total cultivated area; facing devastating biotic and abiotic factors. The estimated economic losses in wheat quantity and quality are about 4 thousands per tonne per year including physical crop losses and handling. Economic losses of about 80–90 million USD in Pakistan are recorded due to inadequate production and handling losses. Wheat agro-ecosystem of the world colonizes many herbivore insects which are abundant and causing significant losses. The feeding style of the insects made them dispersive from one habitat to another imposing significant crop loss. Areas of maximum wheat production are encountered with either insect which chew the vegetative as well as reproductive part or stem and root feeders. This chapter provides the pest’s taxonomic rank, distribution across the globe, biology and damage of chewing and sucking insect pest of wheat. It is very important to study biology of the pest in accordance with crop cycle to forecast which insect stage is economically important, what the proper time to manage pest is and what type of control is necessary to manage crop pest. The chapter will provide management strategies well suited to pest stage and environment

Synergist response of the Peach fruit fly, Bactrocera zonata (Saunders) to some ammonium based proteinaceous food bait attractants

Abstract Background Under the family Tephritidae, Bactrocera zonata (Saunders) is a serious pest, attacking fruits and vegetables causing large quantitative and qualitative damages throughout the world. Fruit flies require proteinaceous food for sexual maturation and egg development. Therefore, food bait attractants are frequently utilized for fruit fly detection, monitoring, mass trapping, and control. Using a Y-shape olfactometer (behavioral tests), we selected the best synthetic proteinaceous food bait attractants to volatiles identified by fruit fly antennae. The responses of B. zonata adults, male and female, to some ammonium compounds (ammonium acetate (AA), trimethylamine (TMA), and putrescine) that were mixed with certain food attractants were evaluated under laboratory conditions. Using flies ranging in age from 5 to 30 days, possible mixtures were discovered that might be useful in developing fruit fly attractants for both males and females. So, four base baits were developed by mixing protein hydrolysate with jaggery, papaya powder, kachri powder, potassium hydroxide (KOH), and guava pulp. Finally, thirty-two (32) synthetic blends were developed when the above four base baits were mixed with synthetic attractants. Results The olfactometer bioassay indicated that protein hydrolysate and jaggery-based baits were effective in attracting both male and female flies throughout their adult lives when combined with AA + putrescine (Bait 6) and AA + TMA + putrescine (Bait 8). Similarly, protein hydrolysate + guava pulp-based baits combined with AA + putrescine (Bait 6) and AA + TMA + putrescine (Bait 8) was effective in attracting both male and female flies from 5 to 30 days of age. The pH of all 32 synthetic blends was measured and ranged from 4.77 to 11.35. Conclusions According to our observation, the variation in pH may be due to differences in chemical composition between the attractants and food constituents. The pH of protein bait attractants may be an important factor in the attraction efficiency of B. zonata males and females

Factors Affecting the Epizootics of Entomopathogenic Fungi-A Review

Entomopathogenic fungi (EPF) specifically infect and kill insects can serve as a potential biological control agent. Several biotic and abiotic factors affect their occurrence, persistence, and epizootics caused by them. In biotic factors, fungi characters (host range, latency, spore density and dispersal, mainly host-pathogen compatibility), insect host factors (behavioral, morphological, and physiological), plant-mediated effects (plant architecture, surface chemistry, and leaf topology) are included supports or causes the barrier to mycobiopesticide. Abiotic factors which affect the EPF field persistence are mainly environmental (temperature, sunlight, humidity, rainfall) physical and chemical soil properties (soil texture, pH, E.c, moisture, C/N content, and organic matter) that greatly influence the entomopathogenic fungi. To use them as biocontrol agents, we have to overcome these factors by providing them nutrients, protectants, and using different control practices

Thiamethoxam Resistance in the House Fly, Musca domestica L.: Current Status, Resistance Selection, Cross-Resistance Potential and Possible Biochemical Mechanisms.

The house fly, Musca domestica L., is an important ectoparasite with the ability to develop resistance to insecticides used for their control. Thiamethoxam, a neonicotinoid, is a relatively new insecticide and effectively used against house flies with a few reports of resistance around the globe. To understand the status of resistance to thiamethoxam, eight adult house fly strains were evaluated under laboratory conditions. In addition, to assess the risks of resistance development, cross-resistance potential and possible biochemical mechanisms, a field strain of house flies was selected with thiamethoxam in the laboratory. The results revealed that the field strains showed varying level of resistance to thiamethoxam with resistance ratios (RR) at LC50 ranged from 7.66-20.13 folds. Continuous selection of the field strain (Thia-SEL) for five generations increased the RR from initial 7.66 fold to 33.59 fold. However, resistance declined significantly when the Thia-SEL strain reared for the next five generations without exposure to thiamethoxam. Compared to the laboratory susceptible reference strain (Lab-susceptible), the Thia-SEL strain showed cross-resistance to imidacloprid. Synergism tests revealed that S,S,S-tributylphosphorotrithioate (DEF) and piperonyl butoxide (PBO) produced synergism of thiamethoxam effects in the Thia-SEL strain (2.94 and 5.00 fold, respectively). In addition, biochemical analyses revealed that the activities of carboxylesterase (CarE) and mixed function oxidase (MFO) in the Thia-SEL strain were significantly higher than the Lab-susceptible strain. It seems that metabolic detoxification by CarE and MFO was a major mechanism for thiamethoxam resistance in the Thia-SEL strain of house flies. The results could be helpful in the future to develop an improved control strategy against house flies

Synergistic effect of enzyme inhibitors on the toxicity of thiamethoxam against house flies strains.

<p>Synergistic effect of enzyme inhibitors on the toxicity of thiamethoxam against house flies strains.</p

Metabolic enzyme activities in the Lab-susceptible and Thia-SEL strains of house flies.

<p>Metabolic enzyme activities in the Lab-susceptible and Thia-SEL strains of house flies.</p

Selection history of the field strain of house flies with thiamethoxam, and subsequent toxicity after four generations without thiamethoxam exposure.

<p>Selection history of the field strain of house flies with thiamethoxam, and subsequent toxicity after four generations without thiamethoxam exposure.</p

Cross-resistance analyses of the field collected strain of house flies to imidacloprid and spinosad after selection with thiamethoxam.

<p>Cross-resistance analyses of the field collected strain of house flies to imidacloprid and spinosad after selection with thiamethoxam.</p