Effect Of Selected Insect Growth Regulators On Delia Antiqua (Meigen) Adult Reproduction

The onion maggot, Delia antiqua （Meigen）, is an important pest threatening garlic, onionand other crops in the the Lily family. The pest occurs regularly in Shandong Province, whichis the main producing area of garlic in China. By far, the most common method to controlonion maggot is to apply organophosphorus insecticides when watering garlic in field, whichleads to insecticides resistance and residue. Pest control methods which aimed at adult areefficient, and they avoid pesticides pollution on crops and environment. As it was reported,insect growth regulators （IGRs） had significant inhibitition effect on reproduction of Dipteraadult, which makes it available for onion fly control. We evaluated the sterilization effect oflufenuron, cyromazine and pyriproxyfen on adult reproduction parameters such as fertility,fecundity and F1larva development. Furthermore, age-specific effect of the potentialchemosterilants and the male’s ability to transmit the sterility effect were determined. Finally,we compared the difference of these potential chemosterilants which belongs to differentIGRs and detected brief mechanism of these potential chemosterilants. The main result wereas follows:1. Stomach toxicity test showed that LC50of clothianidin and emamectin benzoate were3.784and4.505mg kg^-1, which were much lower than LC50of lufenuron, cyromazine andpyriproxyfen(LC50>2000mg kg^-1).2. The seclected IGRs showed excellent sterilizing effects on onion fly through variousmodes of action. Feed treatment of cyromazine inhibitted the fecundity of onion fly.Fecundity of1-day old adult was reduced by29.9%,42.5%and55.6%when onion fly wastreated by cyromazine at100,500,1000mg kg^-1. Also, fertility of cyromazine-treated onionfly was significantly reduced by11.75%,14.25%and70.25%at doses of at100,500,1000mg kg^-1. What’s more, cyromazine prolonged the preoviposition period of onion fly.Lufenuron had no effect on fecundity of onion fly, while it reduced fertility significantly.Fertility of lufenuron-treated onion fly was significantly reduced by62.75%,75.75%and87.25%at doses of at100,500,1000mg kg^-1. Pyriproxyfen at dose of100,500and1000mgkg^-1reduced fecundity of treated adult females by22.4%,60.2%and73.2%, while it had noeffect on fertility. 3. When adults were treated by lufenuron and cyromazine singlely, F1larvaedevelopment was significantly inhibitted. Survival rate of1st instar larvae was reduced by43.2%and67.2%when the parents adults were treated at dose of50and500mg kg^-1lufenuron. Once the larva survived, they pupated normally, and the pupa weight was notaffected. Similar with lufenuron, survival rate of1st instar larvae was reduced by6.5%and15.3%when the parents adults were treated at dose of50and500mg kg^-1cyromazine.4. Lufenuron and cyromazine showed age-specific effect on reproduction of onion fly.Cyromazine inhibited the fecundity of onion fly which did not reach sex maturity, and theyounger the onion fly was, the more susceptible the fecundity of female would be. Fecunndityof1-d,4-d and7-d old onion fly was reduced by45.4%,54.8%;16.5%,40.6%and11.1%,15.6%by cyromazine at doses of50and500mg kg^-1respectively. As the ovary of onion flygot matured, cyromazine would not affect the fecundity. However, the older the adult was, themore susceptible the fertility of onion fly was. Lufenuron had similar effect on fertility withcyromazine, while it had no effect on fecundity of matured and unmatured females of onionfly.5. Female and male adults of onion fly played different role in sterilizing effect oflufenuron and cyromazine. Fertility of treated females was significantly affected no matter themated males were treated by lufenuron or not. So it was with cyromazine. The inhibitioneffect of lufenuron and cyromazine acted through the female adult of onion fly.6. Egg anatomy showed that eymbro in eggs of treated onion fly had developpednormally, while the larvae could not puncture out of the egg shell.7. Fecundity of cyromazine-treated onion fly was significantly reduced. Cyromazineinhibitted the development of follicle in female. Numbers of developped follicle incyromazine-treated female at dose of500,1000mg kg^-1were reduced by44.3%,46.1%and57.6%,60.1%compared to control at the4thand7thday after emergence. What’s more,cyromazine didn’t inhibit accumulation of protein in hemolymph, while it significantlyinhibited accumulation of protein in ovary. Result above indicated that cyromazine may blockthe absorption of protein by oocyte from hemolymph, which might lead to folliculardevelopment inhibition.