Pheromones and Chemical Communication in Insects

Chemical communication is an essential item for insects’ survivals that qualify them to adapt their behavior depending on the surrounding environment. Semiochemicals defined as informative molecules (M) mainly play an important role that conveys specific chemical messages between insect and insect and plant and insect. Olfaction mechanism in insects is a key point of chemical communication between the same and different insect species. Discrimination of various odors through the olfaction system depends only on the evolutionary pressures of the molecules which stimulate the development of specific binding proteins (BPs) and specific receptor sites present on individual chemosensory neurons. Pheromones are defined as species-specific chemical signals which enable communication between life-forms of the same species. Recently, semiochemicals become as alternative or complementary components to insecticide approaches in integrated pest management (IPM) strategies. Pheromones are secreted by insects causing a specific reaction, for example, either a definite behavior or a developmental process. Pheromones have been classified into eight various types: aggregation pheromones, alarm pheromones, oviposition-deterrent pheromones, home recognition pheromones, sex pheromones, trail pheromones, recruitment pheromones, and royal pheromones. Pheromones are promising and can be used singly or in integration with other control strategies for monitoring and controlling insect pests in agricultural systems

Molluscicidal activity of Bacillus thuringiensis strains against Biomphalaria alexandrina snails

Schistosomiasis is a parasitic disease transmitted to man and different warm blooded animals by means of snails. Great effort has been made to control the transmission of the disease by many strategies. Consequently, the utilization of particular molluscicides is viewed as a standout amongst the best measures for molluscs control. Recently, microbial pathogen used as non-traditional molluscicides which have attracted significant research attention due to the increasing, worldwide development of resistance to chemical molluscicides in molluscs populations. The present work aimed to study the molluscicidal impacts of eleven isolates of Bacillus thuringiensis which were isolated from soils of six Egyptian governorates toward Biomphalaria alexandrina snails. Results showed that, B. thuringiensis provides an effective biological control agent against B. alexandrina snails. Out of the tested isolates, four isolates; Qalyubia, Asyut 1, Qena and North Sinai 2 isolates show high-level molluscicidal activity. The obtained results indicated that LC50 and LC90 values were ranged between 133.27â457.74 mg/mL and 270.32â781.05 mg/mL, respectively. The most noteworthy molluscicidal impact was displayed by Qalyubia isolate which isolated from Qalyubia governorate with mortality rate extended from 20% to100% at five treatment concentrations of 100â500 mg/mL. The LC50 and LC90 values for Qalyubia isolate were 133.27 mg/mL and 270.32 mg/mL, respectively. Keywords: Biomphalaria alexandrina, Bacillus thuringiensis, Molluscicidal activity, Biological contro

Semiochemicals for controlling insect pests

Semiochemicals are defined as informative molecules mainly used in plant-insect or insectinsect interactions as alternative or complementary components to insecticide approaches in different integrated pest management strategies. They are used to manipulate insect behaviour by affecting the survival and/or reproduction of insect pests for controlling their infestations on crops. The present review provides a basic summary of the utilization of semiochemicals for controlling insect pests. Two main topics were explored in this study. The first topic focuses on a description of semiochemicals and their types (pheromones and allelochemicals). Pheromones represent an intraspecific communication amidst members of the same species. Allelochemicals, produced by individuals of one species, modify the behavior of individuals of a different species (i.e. an interspecific effect). Allelochemicals include different informative molecules such as: allomones, kairomones, synomones, antimones and apneumones. The second topic focuses on the application of semiochemicals in IPM programs. Different semiochemicals are included in integrated pest management programs in various ways such as monitoring, mass trapping, attract-and-kill, push-pull, and disruption strategies. Pheromones are promising and can be used singly or in integration with other control strategies for monitoring and controlling insect pests in agricultural systems. For example, sex pheromones have been applied in mass trapping, disruption and attract-and-kill tactics in IPM programs

Original Article. An evaluation of some eco-friendly biopesticides against Bemisia tabaci on two greenhouse tomato varieties in Egypt

Th is study has two main approaches. First, it exploits the susceptibility of tomato cultivars as a prophylactic measure to detect auto resistance characters of the tested tomato varieties against Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae). Secondly, it evaluates the efficacy of different bio-rational insecticides against B. tabaci under greenhouse conditions. The results exhibited a special significance in B. tabaci infestation suitability between the two tomato varieties with a high infestation significance found in the Shifa F1 hybrid tomato variety compared to the Savera F1 hybrid tomato variety in the fi rst plantation period. Subsequently, in the second plantation period, there was a significant difference between the two tomato varieties. Bemisia tabaci showed a preference for the Shifa F1 hybrid over the Savera F1 hybrid tomato variety. Th ese diff erences occurred during the 1st, 2nd, 4th, 6th, 7th, 8th, and 10th weeks. In the experimental trial for the efficacy of eco-friendly biorational insecticides, spinosad, azadirachtin, Beauveria bassiana and Metarhizium anisopliae, there were significant differences between the treated and untreated plants during the two plantation periods. A high efficacy of spinosad on the B. tabaci population was found. Bemisia tabaci infestation under all the applications was reduced from 50 to 94.61% for the two plantation periods. This obvious decrease in B. tabaci population increase attention to benefits of the different bio-rational insecticides

An evaluation of some eco-friendly biopesticides against Bemisia tabaci on two greenhouse tomato varieties in Egypt

Th is study has two main approaches. First, it exploits the susceptibility of tomato cultivars as a prophylactic measure to detect auto resistance characters of the tested tomato varieties against Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae). Secondly, it evaluates the efficacy of different bio-rational insecticides against B. tabaci under greenhouse conditions. The results exhibited a special significance in B. tabaci infestation suitability between the two tomato varieties with a high infestation significance found in the Shifa F1 hybrid tomato variety compared to the Savera F1 hybrid tomato variety in the fi rst plantation period. Subsequently, in the second plantation period, there was a significant difference between the two tomato varieties. Bemisia tabaci showed a preference for the Shifa F1 hybrid over the Savera F1 hybrid tomato variety. Th ese diff erences occurred during the 1st, 2nd, 4th, 6th, 7th, 8th, and 10th weeks. In the experimental trial for the efficacy of eco-friendly biorational insecticides, spinosad, azadirachtin, Beauveria bassiana and Metarhizium anisopliae, there were significant differences between the treated and untreated plants during the two plantation periods. A high efficacy of spinosad on the B. tabaci population was found. Bemisia tabaci infestation under all the applications was reduced from 50 to 94.61% for the two plantation periods. This obvious decrease in B. tabaci population increase attention to benefits of the different bio-rational insecticides

Evaluation of some microbial agents, natural and chemical compounds for controlling tomato leaf miner, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae)

Solanaceous plants have a great economic impact in Egypt. These groups of plants include potatoes, tomatoes and eggplants. The new invasive pest of tomatoes, Tuta absoluta (Meyrick) causes the greatest crop losses which can range from 60 to 100%. After its detection in Egypt during the last half of 2009, it spread quickly to all provinces in the country. We aiming to propose a sustainable control program for this devastating pest. In this research we tested three groups of control agents. The first was microbial and natural, the second - plant extracts and the third - chemical insecticides. Our results showed that the impact of T. absoluta can be greatly reduced by the use of sustainable control measures represented by different insecticide groups. Bioassay experiments showed that this devastating pest can be controlled with some compounds that give high mortality rates. Of these compounds, spinosad and Beauveria bassiana, microbial control agents, followed by azadirachtin, gave the best results in controlling T. absoluta. Of the chemical insecticides, lambda-cyhalotrin was the most effective, followed by lufenuron and profenofos. In conclusion we encourage farmers to use microbial and natural control measures in combating the tomato leafminer, T. absoluta, in Integrated Pest Mangement (IPM) programs

Evaluation of some microbial agents, natural and chemical compounds for controlling tomato leaf miner, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae)

Solanaceous plants have a great economic impact in Egypt. These groups of plants include potatoes, tomatoes and eggplants. The new invasive pest of tomatoes, Tuta absoluta (Meyrick) causes the greatest crop losses which can range from 60 to 100%. After its detection in Egypt during the last half of 2009, it spread quickly to all provinces in the country. We aiming to propose a sustainable control program for this devastating pest. In this research we tested three groups of control agents. The first was microbial and natural, the second – plant extracts and the third – chemical insecticides. Our results showed that the impact of T. absoluta can be greatly reduced by the use of sustainable control measures represented by different insecticide groups. Bioassay experiments showed that this devastating pest can be controlled with some compounds that give high mortality rates. Of these compounds, spinosad and Beauveria bassiana, microbial control agents, followed by azadirachtin, gave the best results in controlling T. absoluta. Of the chemical insecticides, lambda-cyhalotrin was the most effective, followed by lufenuron and profenofos. In conclusion we encourage farmers to use microbial and natural control measures in combating the tomato leafminer, T. absoluta, in Integrated Pest Mangement (IPM) programs