StartCoroutine in Collision unwork

Hi,everyone,I make a simply game for the Player touch by the Backteria will explosion, and Mission Fall Image will active , then Player will be destroy , after 5 second load GameOver scene ,but now the question is StartCoroutine(Do());unwork , so I try to use Application.LoadLevel(LevelLoad); straightly , but unwork , too . Does anyone have suggestions?

     using UnityEngine;
     using System.Collections;
     
     public class EatPlayer : MonoBehaviour {
     
         public GameObject explosion;
         public GameObject loadingImage;
         public string LevelLoad; 
     
         void OnCollisionEnter(Collision collider) {
             if (collider.gameObject.name == "Backteria") {
                 StartCoroutine(Do());
                 Destroy(gameObject);
                 loadingImage.SetActive (true);
                 Instantiate(explosion, collider.transform.position, collider.transform.rotation);
                 }
         }
         IEnumerator Do () {
             yield return new WaitForSeconds(5);
             Debug.Log("hhhhhh");
             Application.LoadLevel(LevelLoad);
         }
     }