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喜旱莲子草是水陆两栖的入侵杂草,为探讨在利用其专食性天敌莲草直胸跳甲防治过程中,发现的陆生型喜旱莲子草控制效果不佳的原因,本试验从水分变化的角度,通过设置不同质量分数的聚乙二醇6000(PEG6000)(5%、10%、15%、20%和25%)模拟干旱环境,对喜旱莲子草胁迫处理后,饲喂莲草直胸跳甲幼虫和成虫,记录该跳甲取食后的发育历期、虫重、幼虫死亡情况、化蛹量及羽化量,结果表明:随着水分胁迫程度的加剧,莲草直胸跳甲1~3龄幼虫的发育历期延长,当胁迫质量分数达到25%时,各龄幼虫的发育历期均达到最长;而成虫的寿命随着水分胁迫程度增加而缩短,当胁迫程度为25%时,和对照相比寿命缩短了5.59d;不同虫态的鲜重随着胁迫质量分数的增加均有所下降,其中2龄幼虫和成虫的体重在25%时下降最显著,分别下降了3.19和2.34mg;1龄、2龄和3龄幼虫的死亡率均在胁迫质量分数为25%时达到最大,分别为对照的10.0倍、6.0倍和4.7倍;化蛹率和羽化率随着胁迫程度的加剧均降低,25%时化蛹率和羽化率最低,与对照相比分别降低了33.0%和37.5%。因此,干旱胁迫喜旱莲子草不利于莲草直胸跳甲的生长发育。
Alternanthera philoxeroides is an invasive weed in amphibian. In order to explore the reasons for the poor control effect of terrestrial Alternanthera philoxeroides, In order to simulate the drought environment by setting PEG6000 (5%, 10%, 15%, 20% and 25%) with different mass fractions, Grass larva and adult larvae were recorded. The developmental duration, worm weight, larval mortality, pupation and feathering amount of the hopper were recorded. The results showed that with the aggravation of water stress, When the stress mass fraction reached 25%, the larvae of each instar reached the longest developmental duration, while the longevity of adult larvae shortened with the increase of water stress. When the stress level 25%, compared with the control, the life span shortened 5.59d. The fresh weight of different insect states decreased with the increase of stress mass fraction, and the weight loss of the 2nd instar larvae and adults decreased most significantly at 25% Decreased by 3.19 and 2.34 mg, respectively. Mortality of 1st, 2nd and 3rd instar larvae was significantly higher than that of control 25%, respectively, which were 10.0 times, 6.0 times and 4.7 times that of the control respectively. The pupation rate and emergence rate decreased with the increasing degree of stress, and the pupae rate and emergence rate at 25% Reduce 33.0% and 37.5%. Therefore, the drought stress of Alternanthera philoxeroides is not conducive to the growth and development of the straight thoracic.