Aphid Establishment in the Tropics: Mechanisms of Dispersal, Colonization and Adaptive Evolution: A Critical Review

Aphids are small, oval-shaped phloem-sucking insects that exhibit remarkable polymorphism and complex reproductive strategies, making them highly adaptable and invasive.. With over 5,100 known species globally and approximately 1,000 recognized as pests of agricultural crops, aphids inflict both direct and indirect damage to crop plants, including disease transmission and honeydew deposition, which attracts ants. Globalization has accelerated their unintentional spread beyond native ranges via contaminant and hitchhiking pathways, posing serious threats to agroecosystems and agriculture and horticulture production worldwide. Aphids possess unique reproductive strategies such as, parthenogenesis and alternation between wingless and winged forms, facilitating rapid population growth and colonization. Their phenotypic plasticity and polyphenism, shaped by environmental cues such as temperature and population density, are key to morph determination and survival. While low temperatures are commonly reported to induce winged (alate) morphs, studies also suggest that high temperatures can indirectly affect alate induction. Understanding the interplay between abiotic and biotic factors on aphid biology is essential for predicting invasion dynamics, particularly under climate change scenarios. Future investigations at higher levels of biological organization are crucial to elucidate invasion mechanisms and forecast aphid responses to global warming—thereby contributing to more resilient, sustainable pest management strategies.