Assessment of ecological impacts and pest plant association of pseudococcid insects in Jahangirnagar University Campus, Bangladesh

Abstract

Plants maintain life on earth, and insects form the basal part of the food pyramid, impacting our ecosystem. Among insects, pseudococcids are significant, polyphagous, dimorphic, and notorious sap-sucking plant pests worldwide. To understand the association of these pests with plants and the impact of ecological changes on their population, a year-long initial study in 2004-05 and a review study after two decades in 2023-24 were conducted at Jahangirnagar University Campus, Savar, Bangladesh. The distribution, feeding habits, seasonal dynamics, and ecological impacts of pseudococcid insects on different host plants were assessed through visual counting during fortnightly visits. All diversity parameters indicated a declining trend in pseudococcid fauna with the reduction of floral abundance and diversity. During the first study, 46,464 insects under 5 species (BI = 0.0013, H = 1.17, D = 0.41, 1-D = 0.59, 1/D = 2.45, and EH = 0.73) were recorded from 14 plant species, which have reduced immensely in the recent study of about twenty years later into 6,567 insects belongs to four species (BI = 0.0073, H = 0.77, D = 0.57, 1-D = 0.43, 1/D = 1.75, and EH = 0.56) from eight plant species, including three new species. There was very slight overlap of insect species (CC = 0.222) in the last study; only one old and three new species were identified. Significant differences in insect populations were observed across different months. In both studies, the abundance of infested plants and total plant decreased drastically up to 91.15% and 55.97%, respectively, from 2004 to 2023. The number of shrubs decreased significantly (87.76%, F = 9.6, df = 1, P = 0.008), and the number of host insects declined by up to 85.87%. The infestation rate of trees and shrubs was decreased by 78.11% and 94.17%, respectively. The most suitable host plant, Artocarpus heterophyllus, harbored the maximum number of mealybugs as well as the insect Ferrisia virgata, was abundant round the year that peaked in both studies throughout the summer. Insect fauna, especially F. virgata and Maconellicoccus hirsutus, were found to live on almost all parts of the plants, but the highest number of insects was observed on plant leaves. These findings suggest a gradual decline in biodiversity due to ecological imbalances, emphasizing the need for environmental protection to ensure healthy living.