Bauce É, Crépin M, Carisey N
Centre de Recherche en Biologie Forestière, Université Laval, G1 K 7P4, Sainte-Foy, Quebec, Canada.
Oecologia. 1994 May;97(4):499-507. doi: 10.1007/BF00325888.
Laboratory rearing of spruce budworm, Choristoneura fumiferana, in conjunction with field rearing, gravimetric analyses, a transfer experiment, and foliage chemical analyses at six dates during the period of budworm feeding activity indicated that the age of balsam fir, Abies balsamea, trees (70-year-old mature trees or 30-year-old juvenile trees) affected tree suitability for the spruce budworm via the chemical profile of the foliage. Insects reared on old trees had greater survival and pupal weight, shorter development times, and caused more defoliation than those reared on young trees. Young trees were more suitable for the development of young larvae (instars 2-5), while old trees were more suitable for the development of older, sixth-instar larvae. These results were confirmed by the laboratory transfer experiment. Young larvae fed foliage from young trees had higher relative growth rates (RGR), digestibility (AD), and efficiency of conversion of ingested foliage (ECI) than those fed foliage from old trees. These differences appeared to be related to the high N:tannins ratio, and the high contents of P present in young trees during the development of the young larvae. Old larvae fed foliage from old trees had higher relative growth rates, relative consumption rates (RCR), and digestibility of the foliage than those fed foliage from young trees. The high digestibility of the foliage of old trees was compensated for by a lower efficiency of conversion of digested food (ECD), which in turn resulted in no significant effect of tree age on the efficiency of conversion of ingested foliage by old larvae. The low relative consumption rate of old larvae fed foliage from young trees appeared to be related to the low N:tannins ratio, and the high contents of bornyl acetate, terpinolene, and °-3-carene present in young trees during the budworm sixth instar. Variations in these compounds in relation to tree age may serve as mechanisms of balsam fir resistance to spruce budworm by reducing the feeding rate of sixth instar larvae.
在云杉芽虫取食活动期间的六个日期，结合田间饲养、重量分析、转移实验和树叶化学分析，对云杉芽虫（Choristoneura fumiferana）进行实验室饲养，结果表明，香脂冷杉（Abies balsamea）树的树龄（70年生成熟树或30年生幼树）通过树叶的化学特征影响其对云杉芽虫的适宜性。在老树饲养的昆虫比在幼树饲养的昆虫具有更高的存活率和蛹重，发育时间更短，造成的落叶更多。幼树更适合低龄幼虫（2 - 5龄）的发育，而老树更适合老龄六龄幼虫的发育。实验室转移实验证实了这些结果。取食幼树树叶的低龄幼虫比取食老树树叶的低龄幼虫具有更高的相对生长率（RGR）、消化率（AD）和摄入树叶的转化效率（ECI）。这些差异似乎与低龄幼虫发育期间幼树中高氮：单宁比以及高磷含量有关。取食老树树叶的老龄幼虫比取食幼树树叶的老龄幼虫具有更高的相对生长率、相对取食率（RCR）和树叶消化率。老树树叶的高消化率被较低的消化食物转化效率（ECD）所抵消，这反过来导致树龄对老龄幼虫摄入树叶的转化效率没有显著影响。取食幼树树叶的老龄幼虫相对取食率较低似乎与老龄幼虫六龄期幼树中低氮：单宁比以及高乙酸龙脑酯、萜品油烯和α - 3 - 蒈烯含量有关。这些化合物随树龄的变化可能通过降低六龄幼虫的取食率而成为香脂冷杉对云杉芽虫的抗性机制。
