Helicoverpa zea (Boddie) is a damaging pest of many crops including soybean, Glycine max (L.), especially in the southern United States. Previous studies have concluded that oviposition and development of H. zea larvae mirror the phenology of soybean, with oviposition occurring during full bloom, younger larvae developing on blooms and leaves, intermediate aged larvae developing on varying tissue types, and older larvae developing on flowers and pods. In a field trial, we investigated the presence of natural infestations of H. zea larvae by instar in determinate and indeterminate soybean varieties. In complementary experiments, we artificially infested H. zea and allowed them to oviposit on plants within replicated cages (one with a determinate variety and two with an indeterminate variety). Plants were sampled weekly during the time larvae were present. In the natural infestation experiment, most larvae were found on blooms during R3 and were early to middle instars; by R4, most larvae were found on leaves and were middle to late instars. In contrast, in the cage study, most larvae were found on leaves regardless of soybean growth stage or larval stage. Determinate and indeterminate growth habit did not impact larval preference for different soybean tissue types. Our studies suggest H. zea larvae prefer specific tissue types, but also provide evidence that experimental design can influence the results. Finally, our finding of larval preference for leaves contrasts with findings from previous studies.

中文翻译：

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玉米夜蛾（鳞翅目：夜蛾科）幼虫在有限和不确定大豆植物不同部位的位置


玉米夜蛾（Boddie）是许多农作物的破坏性害虫，包括大豆，大豆(L.)，特别是在美国南部。先前的研究得出结论，产卵和发育玉米幼虫反映了大豆的物候学，产卵发生在盛花期，较年轻的幼虫在花朵和叶子上发育，中龄幼虫在不同的组织类型上发育，较老的幼虫在花和豆荚上发育。在现场试验中，我们调查了自然侵染的存在玉米确定和不确定大豆品种中各龄期的幼虫。在补充实验中，我们人工感染玉米并允许它们在复制的笼子内（一个具有确定品种，两个具有不确定品种）内的植物上产卵。在幼虫存在期间每周对植物进行取样。在自然侵染实验中，大多数幼虫出现在R3时期的花上，并且处于早至中龄；到R4时，大多数幼虫出现在叶子上，并且是中晚期。相比之下，在网箱研究中，无论大豆生长阶段或幼虫阶段如何，大多数幼虫都在叶子上发现。确定和不确定的生长习性并不影响幼虫对不同大豆组织类型的偏好。我们的研究表明玉米幼虫更喜欢特定的组织类型，但也提供了实验设计可以影响结果的证据。最后，我们发现幼虫对叶子的偏好与之前的研究结果形成了鲜明对比。