Selected monocots and eudicots as alternative host plants for promoting arthropod populations in paddy cultivation area

Aim of study: To investigate the relationship between selected alternative host plant species and the abundance of arthropods throughout the growth of rice plants. Area of study: Southwest of Malaysia (Melaka). Material and methods: Sampling of arthropods was conducted in four rice field plots, each containing five sampling plots based on the selected alternative hosts: Chloris barbata Sw. and Oryza sativa L. (monocots); and Ageratum conyzoides L., Spermacoce verticillata L., and Euphorbia heterophylla L. (eudicots). Yellow sticky traps, yellow pan traps, and sweep nets were set up and used, and sampling was conducted during the vegetative, reproductive, and mature stages of rice growth. Analysis of variance (ANOVA) and regression analysis were performed to determine the diversity and relationship between alternative host plants with arthropods. Main results: A total of 2,227 arthropod individuals from 11 orders and suborders, 32 families, and 40 species were recorded. The results showed a strong correlation between alternative host plants and pests (R2 = 0.965), predators (R2 = 0.758), and other insects (R2 = 0.987), while a weaker correlation (R2 = 0.369) was observed with parasitoids. A significant pest decline was observed in A. conyzoides (β = -0.725, P = 0.040) and S. verticillata (β = -1.505, P = 0.034), while there was a substantial population increase in C. barbata (β = 1.854, P = 0.026). Other insects showed a significant population increase in O. sativa (β = 0.752, P = 0.030). However, predatory insects and parasitoids did not show significant population trends during the sampling period in any of the alternative hosts. Research highlights: The planting of alternative hosts in rice cultivation areas can attract natural enemies of insects and improve Integrated Pest Management (IPM) practices in rice fields.