Dietary effect of phytoecdysteridal extracts of Dianthus orientalis Adams (Caryophyllacae) on fecundity of Plutella xylostella (L.)
عنوان دوره: دومین کنگره بین المللی حشره شناسی ایران
نویسندگان
چکیده
Phytoecdysteroids are secondary compounds that act as insect steroid hormones (ecdysone) controlling the insect growth, development and reprouction. The experiment was designed to study the effect of phytoecdysteroid extract of D. orientalis on reproduction of diamondback moth (DBM) Plutella xylostella (L). At first, 50g powder matrial (arial parts) was extracted 3 times using MeOH 70% in ultrasonic bath and then were filtered and concentrated using a rotary evaporator. After that, the extract was centrifuged and supernatant was applied onto the Cartridges, by successive elutions with 5 mL of the following percentages of methanol in water: 10% (Sp 10), 60% (Sp 60) and 100 % (Sp 100) according to a standard procedure. Sp 60 has most ecdysteroids. Thereafter, leaves of canola were exposed to constant concentrations of 2%, 5%, 10%, 20% and 40% (Sp 60+ methanol) of crude extract. Finally, third instar larvae were fed with treated leaves and the number of female offspring was recorded. All experiments were conducted at 27 ± 1 ºC, 65±5% RH and a photoperiod of 16:8 (L: D) h in a growth chamber. The results of this study clearly showed that fecundity was decreased from 136.05 egg/female in control to to 35.47 egg/female at 40 %,. It shows DBM is a susceptible or semi- susceptible to these copmounds. It seems that exact concentration has a critical role causing significant adverse effects on reproduction. In conclusion, if phytoecdysteroidal extract is used tactfully, it may be useful in integrated pest management (IPM). As an overall, our results can support this hypothesis that phytoecdysteroids has a role in plant defences against phytophagous insects.
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