Department of Systematic Zoology and Ecology, Loránd Eötvös University, Pázmány Péter sétány 1/C, Budapest, 1117, Hungary.
Department of Zoology, Plant Protection Institute, Hungarian Academy of Sciences, Herman Ottó út 15, Budapest, 1022, Hungary.
BMC Ecol Evol. 2021 Sep 8;21(1):171. doi: 10.1186/s12862-021-01892-9.
The host specificity and host range of the dry bean beetle, Acanthoscelides obtectus (Coleoptera: Chrysomelidae, Bruchinae), a seed predator of beans, is poorly known. In addition, the female oviposition preference and larval performance relationship is complicated by the respective importance of seed coat and cotyledon, because, paradoxically, females lay eggs on the basis of stimuli of the seed coat alone, without directly being able to assess the quality of the cotyledon's suitability for larval development. Conversely, the thickness of seed coat may prevent first instar larvae from entering the seeds, even if cotyledons are suitable for development.
The seeds of 62 leguminous species and 75 cultivars and accessions occurring in Hungary were evaluated for preference-performance relations. The preference of female bean beetles for seeds was measured in no-choice egg-laying tests. The ability of first instar larvae to overcome the seed coat as a physical barrier was tested with intact seed coat, while pre-drilled seed coats allowed the larvae to assess the suitability of cotyledon for development. The number of emerging adults was recorded. The thickness of seed coats and the weight of seeds were measured. Nonparametric tests and logistic regression were used for the statistical analyses of data and effect sizes were also calculated.
Seeds of 18 leguminous species (35% of them Lathyrus) supported larval development to adults if the seed coat was pre-drilled; however, only nine leguminous species supported development to adults if the seed coat was intact. Seed coat thickness beyond a critical threshold of 0.1 mm strongly influenced survival of first instar larvae. There was no overall positive correlation between oviposition preference and larval performance, except for 16 so-called acceptable non-hosts (Kendall's τ = 0.3088). A. obtectus females also showed an ovipositional hierarchy of legume species even in no-choice tests.
The results suggest that whereas the use of some acceptable non-host species by the A. obtectus is possible in seed stores, the same is unlikely under outdoor conditions, where the recognition of a diverse set of seed pod-related compounds would be necessary to induce egg-laying.
作为豆类种子捕食者的豆象（鞘翅目：叶甲科，豆象亚科），其宿主特异性和宿主范围知之甚少。此外，雌虫产卵偏好和幼虫表现之间的关系很复杂，这是因为种子的种皮和子叶各自的重要性，因为矛盾的是，雌虫仅仅根据种皮的刺激产卵，而不能直接评估子叶适合幼虫发育的质量。相反，种皮的厚度可能会阻止第一龄幼虫进入种子，即使子叶适合发育。
评估了 62 种豆科植物物种和 75 个品种和品系的种子，以确定偏好-表现关系。在无选择产卵测试中测量雌豆象对种子的偏好。用完整的种皮测试了第一龄幼虫克服种皮这种物理障碍的能力，而预先钻孔的种皮允许幼虫评估子叶的发育适宜性。记录成虫的数量。测量种皮的厚度和种子的重量。使用非参数检验和逻辑回归对数据进行统计分析，并计算效应大小。
如果种皮预先钻孔，18 种豆科植物（其中 35%为雀麦属）的种子支持幼虫发育为成虫；然而，如果种皮完整，只有 9 种豆科植物的种子支持幼虫发育为成虫。种皮厚度超过 0.1mm 的临界阈值强烈影响第一龄幼虫的存活率。除了 16 种所谓的可接受非宿主（肯德尔τ=0.3088）外，产卵偏好和幼虫表现之间没有总体上的正相关关系。即使在无选择测试中，豆象雌虫也表现出对豆科植物物种的产卵层次结构。
结果表明，虽然 A. obtectus 可能在种子库中利用一些可接受的非宿主物种，但在户外条件下不太可能，因为需要识别出多种多样的与豆荚相关的化合物才能诱导产卵。
