Side Effects of Five Pesticides on Trichogramma brassicae Bezdenko (Hymenoptera: Trichogrammatidae)

Jalal Shirazi ； Arghavan Bahrami ； Mohammadreza Rezapanah

《農林學報》 66卷1期 (2018/03) Pp. 57-68

https://doi.org/10.30089/JAF.201803_66(1).0006

摘要

Trichogramma brassicae is a dominant species of Trichogrammatids in Iran. It has been widely used in biological control programs against various pests of agricultural crops. Recent surveys demonstrated a late occurrence of its natural population in rice fields coincided with lower percent parasitism of striped stem borer eggs, Chilo suppressalis (Walker). Chemical side-effects were proposed to be the main cause. We chose five pesticides, i.e., diazinon and neem (insecticide), edinfenphos (fungicide) and butachlor and oxadiargyl (herbicide) based on their frequent application in rice fields. Immature stages of the parasitoid (as parasitized eggs of Sitotroga cerealella) at 1, 3 and 7 days after parasitism and newly emerged and mated adults (age ＜24 h) were exposed to the field recommended doses (FRD) of the pesticides at 25 ± 1°C, 65 ± 10% RH and 16:8 (L:D) h photoperiod. Mortality and fecundity of treated insects were calculated based on IOBC guideline. Diazinon caused 95% to 100% mortality on all life stages of the wasp and was considered as harmful (rank 4). The total effects of butachlor, oxadiargyl, edinfenphos and neem on T. brassicae immature were all ranked as rank 1. However, butachlor, edinfenphos and oxadiargyl showed high mortality to adult stages of the parasitoid. Among all pesticides tested, neem with 14.42, 15.99, 22.07 and 16.21 percent of total effect on egg, larva, pupa and adult stages, respectively, was classified as completely harmless to T. brassicae. Therefore, the application of diazinon should be prevented in rice field when T. brassicae is considered as biological control agent. Moreover, spraying butachlor, edinfenphos and even oxadiargyl should be avoided when adult parasitoids exist in the rice field.

關鍵字

Trichogramma brassicae ； Pesticides ； Side effects ； Rice