Impact Of Sublethal Doses Of Imidacloprid, Abamectin And Beta-cypermethrin On Two Color Morphs Of Pea Aphid(Acyrthosiphon Pisum (Harris))

Pea aphid, Acyrthosiphon pisum (Harris)(Hemiptera: aphidiae), including redand green morph, is a destructive agricultural pest of a wide range of leguminouscropsand forage grass. Researches showed that the green morph of pea aphids waswidespread in our country, but the red morph only had been discoveried In thewestern area and the population of red morph have strong reproductive capacity,especially green morph of pea aphid had increased obviously in recent years. Peaaphid had became control focus because it have strong reproductive capacity,especially green morph of pea aphid had increased obviously. To understand clearlythe effects of sublethal dosage of imidacloprid, abamectin and beta-cypermethrin onthe experimental population parameter and detoxifying enzymes of red and greenmorph of pea aphid, and to investigate the relationship between the development,reproduction of A. pisum and sublethal dosage, an experiment was conducted that A.pisum were treated by different concentrations of imidacloprid, abamectin andbeta-cypermethrin in the laboratory using life table method respectively. The mainresults are as follows：1. Determination of toxicity and sublethal doses of three insecticides on two colormorph of pea aphid, Acyrthosiphon pisumThe results showed that the red and green morph of pea aphid in the toxicity ofthree insecticides on decreased in order of abamectin> beta-cypermethrin>imidacloprid. The LC50, LC20, LC10and LC5of abamectin on red morph were0.41,0.14,0.08and0.05mg/L, on green morph were0.40,0.11,0.05and0.03mg/L,respectively; The LC50, LC20, LC10and LC5of beta-cypermethrin on red morph were2.12,0.78,0.46and0.31mg/L, on green morph were2.34,0.83,0.49and0.31mg/L,respectively; The LC50, LC20, LC10and LC5of imidacloprid on red morph were4.35,1.59,0.94and0.61mg/L, on green morph were5.34,1.63,0.88and0.53mg/L,respectively.2. Effect of sublethal doses of three insecticides on the fecundity and longevity oftwo color morph of pea aphid, Acyrthosiphon pisumThe results showed that the fecundity and longevity of two color morph of peaaphid treated by sublethal doses of imidacloprid, abamectin and beta-cypermethrinwere affect significantly. The fecundity and longevity of two color morph of pea aphidtreated by LC20of three insecticides were significantly lower than those of the control, but no significant regulations were found on the fecundity and longevity of two colormorph of pea aphid treated by LC10and LC5of three insecticides, for example, thelongevity of red morph treated by imidacloprid LC10had no significant differencewith those of the control was7.80d, and the fecundity of green morph treated bybeta-cypermethrin LC5was significantly higher than those of the control, and reachedits manimum value, which was70.87.3. Effect of sublethal doses of three insecticides on F1generation of two colormorph of pea aphid, Acyrthosiphon pisumThe Population parameter of net reproductive rates (R0), intrinsic rate of increase(rm), rate of increase(λ), time (t) for population doubling and mean generation time (T)of F1generation of two color morph of pea aphid treated by sublethal doses of threeinsecticides were studied using life table method respectively. The results showed thatthe net reproductive rates (R0) of F1generation of red morph treated byabamectinLC20(41.63), beta-cypermethrin LC20(30.93) and LC10(30.20) weresignificantly lower than those of the control, respectively, but the rest of treatmentshad no significant difference with those of the control, The intrinsic rate of increase(rm) of F1generation of red morph treated by abamectinLC10(0.24) was significantlylower than those of the control. The net reproductive rates (R0) of F1generation ofgreen morph treated by beta-cypermethrin LC20(39.13) was significantly lower thanthose of the control. The survival rate of F1generation of red morph were higher thanthose of the control except treated by imidacloprid LC20, but F1generation of greenmorph treated by all sublethal doses of three insecticides were higher than those of thecontrol. The fecundity of F1generation of red morph treated by all sublethal doses ofthree insecticides had more obvious rule than F1generation of green morph.4. Effect of sublethal doses of three insecticides on detoxifying enzymes of twocolor morph of pea aphid, Acyrthosiphon pisumThe results showed that The specific activity of acetylcholinesterase(AChE),glutathione S-transferases(GSTs) and mixed function oxidases(MFO) of two colormorph pea aphid were affected by treating time and sublethal doses. The GSTsspecific activity of green morph treated by sublethal doses of three insecticidesreached its manimum value at0h, but the AChE and GSTs specific activity of red andgreen morph showed a trend to be from higher to lower, even two peaks. The specificactivity of AChE of red morph treated by sublethal doses of three insecticides werelower than green morph, but the specific activity of GSTs of red morph treated by sublethal doses of three insecticides were higher than green morph except theated byimidacloprid LC10. The specific activity of MFO of the control of red morph washigher green morph, but there was a adverse regulation after treated.