Cooper W Rodney, Rieske Lynne K
United States Department of Agriculture-Agricultural Research Service, Western Integrated Cropping Systems Research Unit, Shafter, CA 93263, USA.
Environ Entomol. 2010 Jun;39(3):787-97. doi: 10.1603/EN09382.
Gall wasps (Hymenoptera: Cynipidae) induce structures (galls) on their host plants that house developing wasps and provide them with protection from natural enemies. The Asian chestnut gall wasp, Dryocosmus kuriphilus Yasumatsu, is an invasive pest that is destructive to chestnut (Castanea spp.). An improved understanding of the interactions among D. kuriphilus, its host, and its natural enemies is critical for the development of effective management strategies against this pest. The objective of our study was to evaluate the D. kuriphilus community interactions, and relate these interactions to variations among gall traits. Galls were collected from four locations throughout the eastern United States from May (gall initiation) through August (after gall wasp emergence), and January. Gall characteristics (volume, weight, and schlerenchyma layer thickness), gall inhabitants (D. kuriphilus, parasitoids, and chamber fungi), and other community associates (insect herbivores and lesions thought to be caused by endophytes) were evaluated and correlated using canonical correlation analyses. The primary mortality factors for D. kuriphilus were parasitism, gall chamber-invading fungi, and failure of adult gall wasps to emerge. Larger gall size and thicker schlerenchyma layers surrounding the larval chambers were negatively correlated with parasitoids and chamber fungi, indicating these gall traits are important defenses. External fungal lesions and insect herbivory were positively correlated with the absence of D. kuriphilus within galls. This study provides support for the protective role of cynipid galls for the gall inducer, identifies specific gall traits that influence gall wasp mortality, and improves our knowledge of D. kuriphilus ecology in North America.
瘿蜂（膜翅目：瘿蜂科）会在其寄主植物上诱导形成瘿结构，这些瘿为发育中的瘿蜂提供栖息之所，并保护它们免受天敌侵害。亚洲栗瘿蜂，Dryocosmus kuriphilus Yasumatsu，是一种入侵性害虫，对栗属（Castanea spp.）植物具有破坏性。更好地理解亚洲栗瘿蜂与其寄主及天敌之间的相互作用，对于制定有效的防治该害虫策略至关重要。我们研究的目的是评估亚洲栗瘿蜂的群落相互作用，并将这些相互作用与瘿性状的变化联系起来。从美国东部的四个地点收集瘿，时间从5月（瘿开始形成）到8月（瘿蜂羽化后），以及1月。使用典范相关分析评估并关联瘿的特征（体积、重量和厚壁组织层厚度）、瘿内居民（亚洲栗瘿蜂、寄生蜂和腔内真菌）以及其他群落成员（昆虫食草动物和被认为由内生菌引起的损伤）。亚洲栗瘿蜂的主要死亡因素是寄生、侵入瘿腔的真菌以及成年瘿蜂羽化失败。较大的瘿大小和围绕幼虫腔的较厚厚壁组织层与寄生蜂和腔内真菌呈负相关，表明这些瘿性状是重要的防御机制。外部真菌损伤和昆虫食草作用与瘿内亚洲栗瘿蜂的缺失呈正相关。本研究为瘿蜂瘿对瘿诱导者的保护作用提供了支持，确定了影响瘿蜂死亡率的特定瘿性状，并增进了我们对北美亚洲栗瘿蜂生态学的了解。
