Environmental Safety Evaluation Of Periplocosides Based Insecticides

Periploca sepium Bunge, as a Asclepiadaceae Periploca deciduous creeping shrub, hasstrong insecticidal activity.10%micro emulsion of extracts from Periploca sepium (10%ME)and15%emulsion in water of extracts from Periploca sepium (15%EW) had been developedby Institution of Pesiticide Science, Northwest A&F University, which showed good controlefficiency to Plutella xylostella and Pierisrapae in field. This dissertation focused particularlyon the studies of environmental safety evaluation of extracts of root bark from Periplocasepium (ERBPS),10%ME and15%EW. The main results are as follows:1. Toxicity on non-target organisms:(1) The oral LD50and dermal LD50to rats of periplocosides based insecticides were morethan5000mg/kg. The inhalation toxicity to rats was slightly. Both of them had no or lowirritation to skin and mild-to-moderate irritation to eyes of rabbit. The dermal allergy testshowed that they didn’t induce allergic reaction in guinea pigs.(2) Periplocosides based insecticides had non-contact toxicity and low stomach toxicityto bees. The24h stomach LC50of ERBPS,10%ME and15%EW were5107.99mg/L,2600.42mg/L and3473.70mg/L.(3) The acute oral toxicity to quail of periplocosides based insecticides were low, and thecumulative toxicity were mild with cumulative coefficient of5.30.(4) Periplocosides based insecticides has low acute toxicity to carps with24h LC50of206.33mg/L,322.74mg/L and104.97mg/L.(5) Periplocosides based insecticides had no contact toxicity to silkworms, and thestomach toxicity were low, their72h LC50were5875.80mg/L,3148.09mg/L and2909.39mg/L, respectively.10%ME has little impact on weight of silk and silkworm chrysalis,however, the loss rate of silk and silkworm chrysalis in group10%EW were as high as40.17%and15.91%, respectively. Moreover, extracts of root bark from Periploca sepium hadstrong antifeedant effect, which had a certain impact on the silk and silkworm chrysalis.(6) The acute toxicity to earthworms of periplocosides based insecticides were low, andthe14d LC50were624.44mg/L,1082.49mg/L and1411.00mg/L, respectively. (7) Periplocosides based insecticides had no contact toxicity to ladybirds. Their stomachtoxicity were low with24h LC50of1300.87mg/L,1540.29mg/L and3394.08mg/L,respectively.(8) The acute toxicity to tadpoles of periplocosides based insecticides were low, and the24h LC50were597.59mg/L,892.16mg/L and646.44mg/L, respectively.2. The behavior of periplocoside P in the environment:(1) The migration performance of periplocoside P in the black soil from Northeast ofChina was weak (Grade Ⅰ, Rf=0.08). In the red soil from Jiangxi province and soil fromHenan province, the migration performance were weak (Grade Ⅱ, Rf=0.17,0.13).(2) The half-life of periplocoside P in wheat soil, vegetable soil and fruiter soil were4.33d,3.85d and4.25d, respectively, which means periplocoside P was low residual in thesethree kinds of soil.(3) Abiotic hydrolysis of The periplocoside P in different water had related to dielectricpH value and temperature. In25℃, the half-life of periplocoside P in pH5,7and9were4.28d,5.97d and2.38d, respectively. In50℃, the half-life of periplocoside P in pH5,7and9were3.57d,3.96d and2.36d, respectively. All the half-life were less than one month,which indicated that periplocoside P is easy to hydrolysis in environment.The results showed that，the periplocosides based insecticides are generally safe tonon-target organisms, but they should be applied cautiously in mulberry field. In addition,they can be degraded fast in soil and water, which is considered as a novel kind ofenvironment-friendly insecticide.