Determination on Toxicities of Two Phoxim Formulations to Larvae of Holotrichia parallcl

[Objective] The study aimed to determine the toxicities of phoxim CS and phoxim ES to the larvae of Holotrichia parallcl.[Method] On base of the preliminary establishment of indoor breeding method for H.parallcl and its larvae,the phoxim 30CS was matched into 5 concn.of 0.16,0.32,0.64,1.28 and 2.56 μg/g and the phoxim 41.2EC was matched into 5 cencn.of 0.08,0.16,0.32,0.64 and 1.28 μg/g,the indoor toxicities of 2 phoxim formulations to 7-day-old larvae of H.parallcl were determined by using the soil mixing medicine method and the larvae mortality and adjusted mortality were investigated and calculated after treatment for 24 h.[Result] The 41.2% phoxim EC had higher toxicities to the larvae of H.parallcl,with the LC50 and LC90 being 0.39 and 1.18 mg/kg resp.The phoxim ES had lower toxicities to the larvae of H.parallcl,with the LC50 and LC90 being 1.09 and 2.68 mg/kg resp.,reasoning that the phoxim wrapped up in the microcapsule could not be fully released and did not play its full role.[Conclusion] When the phoxim CS was used to control the larvae of H.parallcl,the quantity of the phoxim outside the capsule in the soil only reached to over 1.18 mg/kg,that it could obtain the efficient control effects.