What term refers to the method by which insects can transmit diseases via their body surfaces?

The term that refers to how insects can transmit diseases via their body surfaces is mechanical transmission. This process occurs when an insect picks up a pathogen from one host or environment and then transfers it to another host without the pathogen undergoing any development or multiplication within the insect's body. Instead, the pathogen can simply adhere to the insect’s body, such as its legs or mouthparts, and be transmitted to a new host when the insect comes into contact with it.

In contrast, biological transmission involves a more complex relationship, where the pathogen develops and multiplies within the vector. Direct transmission usually refers to the transmission of pathogens directly from one host to another without an intermediary, while environmental transmission describes how pathogens exist in and are spread through the environment, influencing disease spread but not directly involving insects as vectors.