Chemotherapeutic agents. IX. Synthesis and pesticidal activities of bis[4‐aryl/alkyl‐1, 2, 4‐triazoline‐5‐thione‐3‐yl]alkanes and 1 ‐Aryl/alkyl‐3‐[4‐(4‐aryl/alkyl‐1, 2, 4‐triazoline‐5‐thione‐3‐yl)phenyl]thiourea and related compounds