Sugar-feeding by adult ichneumonoid and stephanoid wasps (Hymenoptera) in dry evergreen forest, Thailand

Many temperate parasitoid wasp species are known to consume sugars as
adults. However, little is known about their adult nutritional ecology in
the tropics. Here we present the results of sugar analyses of adult
parasitoid wasps collected in dry evergreen forest in Thailand. Sugars
were detected using cold anthrone tests, and the results validated for a
subsample using high-performance anion-exchange chromatography with pulsed
amperometric detection (HPAEC-PAD). Sugars were detected in 90% of
stephanids (n=218), 81% of ichneumonids (n=563), and 60% of braconids
(n=1,665). We examined whether the presence or absence of sugar and the
amount detected were influenced by family (Braconidae, Ichneumonidae,
Stephanidae), body size, sex, life history strategy (idiobiont,
koinobiont), or weather (rainy vs drier months). Both the incidence of
sugar-feeding and the amount detected were strongly positively correlated
with body size, and season. Larger individuals were significantly more
likely to be sugar positive as well as individuals collected in the dry
season. However, family (Braconidae vs Ichneumonidae) was also a
significant factor for incidence of sugar-feeding. Sugar-feeding
prevalence was significantly associated with life history strategy in both
families but in opposite directions: koinobiont ichneumonids were more
likely to have fed on sugar, whereas koinobiont braconids were less
likely. Sugar feeding by braconid wasps was significantly more likely
during rainy months. When interactions between variables were taken into
account, these relations also changed with weather and weather:size and
weather:size:life history interactions being significant for ichneumonids,
but for braconids the significant explanatory variables were size, life
history and size:life history interaction.

已知诸多温带寄生蜂（temperate parasitoid wasp）成虫会摄取糖类物质，但目前学界对热带地区寄生蜂成虫的营养生态学却知之甚少。在此我们呈现了在泰国干旱常绿林采集的寄生蜂成虫的糖类分析结果。

研究采用冷蒽酮试验（cold anthrone test）检测糖类，并通过高效阴离子交换色谱-脉冲安培检测法（HPAEC-PAD）对部分子样本的检测结果进行了验证。在218头肿腿蜂科（Stephanidae）标本中，糖类检出率为90%；563头姬蜂科（Ichneumonidae）标本中检出率为81%；1665头茧蜂科（Braconidae）标本中检出率为60%。

本研究探究了糖类检出与否、检出量是否受以下因素影响：科属（茧蜂科、姬蜂科、肿腿蜂科）、体型大小、性别、生活史策略（抑性寄生idiobiont、容性寄生koinobiont）以及气候条件（雨季与旱季）。糖类摄取率与检出量均与体型大小及季节呈显著正相关：体型更大的个体以及旱季采集的标本，糖类检测呈阳性的概率显著更高。不过科属（茧蜂科与姬蜂科的对比）同样是影响糖类摄取率的显著因素。

两个科的寄生蜂糖类摄取率均与生活史策略显著相关，但关联方向相反：容性寄生的姬蜂科物种糖类摄取概率更高，而容性寄生的茧蜂科物种摄取概率更低。茧蜂科寄生蜂的糖类摄取在雨季显著更为普遍。

当考虑变量间的交互效应时，上述关联会随气候条件发生变化：对于姬蜂科而言，气候、气候×体型以及气候×体型×生活史的交互效应均具有统计学显著性；而对于茧蜂科而言，具有显著解释力的变量为体型、生活史策略以及体型×生活史的交互效应。