抗虫和感虫大豆混播对产量及害虫种群发生和昆虫群落多样性影响

Effects of sowing mixed crops of resistant and susceptible cultivars of soybean on crop yield, the population dynamics of key insect pests and insect community diversity

【目的】利用大豆高抗虫和高感虫品种混播,明确有效控害保产的最优比例,以实现大豆生产中有效的害虫生态防控和提高大豆产量。【方法】本研究选取高抗(Lamar;R)和与高感(JLNMH;S)斜纹夜蛾Spodoptera litura的大豆品种,进行不同比例的种子混播种植(即R、S单作,90%R和10%S(9R1S)、80%R和20%S(8R2S)、70%R和30%S(7R3S)、50%R和50%S(5R5S)混播),探究对大豆产量和主要害虫种群发生及昆虫群落多样性的影响。【结果】不同比例混播处理间斜纹夜蛾和筛豆龟蝽Megacopta cribraria的百株虫量无显著差异,但均显著低于S单作。混播处理8R2S和9R1S以及R单作下昆虫群落多样性指数(H)和均匀度指数(E)显著高于其他试验处理,而优势度指数(C)显著低于其他试验处理。此外,昆虫群落丰富度指数(D)随着高感虫大豆混播比例的增加而降低;其中,混播处理8R2S和9R1S,以及R单作都显著高于S单作。对于大豆产量,混播处理显著影响大豆百株籽粒重,但对千粒重的影响不明显。其中,R单作和9R1S混播方式下大豆百株籽粒重最高,且有随着高抗虫品种(R)混播比例的增加而提高的趋势。【结论】高抗虫和高感虫品种混播可有效降低大豆主要害虫发生,且R混播比例≥80%能有效提高昆虫群落多样性、均匀度和丰富度,并对大豆产量提高有利。大豆生产中,建议采用80%以上的高抗虫品种与高感虫品种混播以实现大豆控害保产的生态防控效果。

[Objectives] To identify the optimal ratio of resistant(R) and susceptible(S) soybean cultivars that should be sown to reduce insect pest numbers and maximize crop yield, thereby achieving the maximum possible soybean yield without pesticide use. [Methods] Different ratios of soybean varieties that were either resistant(cv. Lamar) or susceptible(cv. JLNMH) to Spodoptera litura were sown(R and S monocultures plus four mixed crops;90% R and 10% S(9R1S), 80% R and 20% S(8R2S), 70% R and 30% S(7R3S), and 50% R and 50% S(5R5S)), to determine the effects of each seed ratio on soybean yield, the population dynamics of key insect pests(S. litura and Megacopta cribraria) and insect community diversity. [Results] There was no significant difference in the number of individual S. litura and M. cribraria per 100 plants among the different sowing treatments, but all treatments had significantly fewer of these species than the S monoculture. The insect community diversity index(H) and evenness index(E) of the 8R2S, 9R1S and R treatments were significantly higher than those of the other treatments, whereas the dominance index(C) of these three treatments were significantly lower than those of the other treatments. In addition, the insect community richness index(D) was lower when greater proportions of the sensitive cultivar were sown, and the richness index(D) of the 8R2S, 9R1S and R treatments was significantly higher than that of the S treatment. Sowing different cultivars significantly affected the dry weight of grain per 100 plants but there was no obvious effect on the 1000-grain dry weight. The R and 9R1S treatments had the highest grain dry weight per 100 plants, and this tended to increase with the proportion of resistant cultivar sown. [Conclusion] Sowing a mixture of resistant and susceptible cultivars can efficiently reduce the abundance of major soybean pests, and sowing ≥ 80% of the resistant variety significantly improves the diversity, evenness and richness of the insect community, and soybean yield. Consequently, we recommend sowing > 80% resistant soybean seed to control soybean pests and improve yield.