Issue 2

Nitrogen (N) fertilization reduces worldwide food insecurity by boosting crop yield and stability. N is one of the most essential macromolecules required for the growth and reproduction of plants. It occurs in diverse chemical forms and circulates in natural and agricultural ecosystems. It is a constituent of chlorophyll, hence is required for the photosynthesis of plants. Plants receive N through their roots in the form of ammonia or nitrate. Nutritional quality and defense of plants that have a direct impact on herbivorous insects are altered by N fertilization and herbivorous insects can differentiate between plants that receive different applications of N fertilizer. Increasing N fertilization has a variable impact on plant species composition, plant growth, plant biomass, and yields. Plant tissue N and protein contents are also affected by nitrogen fertilization. Moreover, nitrogen fertilization affects many aspects of insects such as population dynamics, larval count, larval weight, feeding choice, and oviposition preference. Furthermore, predatory insect abundance, parasitization performance, and development of parasitoids on host insects are negatively affected by N fertilization. Other important effects of N fertilization are the hemolymph protein profile of herbivores, emission of VOCs, phytohormone biosynthesis, and direct and indirect defense of plants. The aim of this literature research is to demonstrate the effects of variable doses of N fertilization on the crop-herbivore-natural enemy tri-trophic systems. The information gathered in this review might help researchers understand the impact of optimal and excessive N fertilization on crop production and food security.

The present study was initiated to detect and quantify pesticide residues in three selected major vegetables (hyacinth bean, cauliflower and yard long bean) collected from 5 local markets of Gazipur district of Bangladesh. The vegetable samples were prepared by Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) extraction technique and analyzed by Gas Chromatography (GC) equipped with Flame Thermionic Detector (FTD). In this study, 45 vegetable samples were analyzed. Out of 15 samples of hyacinth bean, 2 samples (13% of the total samples) contained pesticide residues above MRL and the remaining samples did not contain any detectable pesticide residues. In the instance of cauliflower, 2 samples (13% of the total number of samples) contained pesticide residues above MRL, while the remaining samples had no detectable pesticide residues. Pesticide residues with levels exceeding MRL were found and measured in 3 samples (20% of the total number of samples) from 15 yard long bean samples. From remnant samples, no pesticide residue was detected. This study depicts the overall scenario of pesticide contamination in vegetables specially in hyacinth bean, cauliflower and yard long bean available in the local markets of Gazipur city, Bangladesh. As a result, it is important to intensify routine pesticide residue monitoring in commercially cultivated vegetables.

This study was initiated to develop an accurate analytical method for the determination of neonicotinoid and organophosphorus insecticide using Liquid Chromatography tandem Mass Spectrometry (LC-MS/MS). Several experiments were conducted to select the parent ion and precusor ion and based on this outcome, the analytical method for the determination of thiamethoxam and dimethoate using LC-MS/MS was developed. The heated electrospray ionization (HESI) mode was used to develop the method.  The linearity of the developed analytical method was very good and it was 0.998 for both of the selected pesticides. The optimization of MS/MS parameters has been done properly for both of the selected pesticides through direct infusion of 100 ug/L standard solutions.

The study was carried out to detect and quantify the left over residue of fenvalerate and acephate in tomato and yard long bean using Gas Chromatography coupled with Flame Thermionic Detector. Four supervised field trials were undertaken sprayed with the prescribed dose of fenvalerate at the rate of 1mL/L of water and acephate at the rate of 2g/L of water. The samples of tomato and yard long bean were collected at 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 and 15 days after spray (DAS). The residue of acephate was detected up to 11 DAS in tomato and 14 DAS in yard long bean and all of the detected quantities were above Maximum Residue Limit (MRL) set by European Union. No residue was detected at 12 DAS in tomato and 15 DAS in yard long bean. The residue of fenvalerate was detected up to 12 DAS in tomato and 13 DAS in yard long bean, of which the quantities of residue of fenvalerate was above EU-MRL at 9 DAS in tomato and 11 DAS in yard long bean. Fenvalerate contained 0.076-0.008 mg/kg residue in tomato and 0.049-0.021 mg/kg residue in yard long bean which were below EU-MRL at 10 to 12 DAS in tomato and 12 to 13 in yard long bean which were below EU-MRL. No residue was detected at 13 DAS in tomato and 14 DAS in yard long bean. So, in case of acephate the pre-harvest interval (PHI) was determined at 12 DAS in tomato and 15 DAS in yard long bean and for fenvalerate it was 10 DAS in tomato and 12 DAS in yard long bean.