Higher plasticity in feeding preference of a generalist than a specialist: experiments with two closely related Helicoverpa species

Abstract

Herbivorous insects have been categorized as generalists or specialists depending on the taxonomic relatedness of the plants they use as food or oviposition substrates. The plasticity in host plant selection behavior of species belonging to the two categories received little attention. In the present work, fifth instar caterpillars of the generalist herbivore Helicoverpa armigera and its closely related species, the specialist Helicoverpa assulta, were fed on common host plants or artificial diet, after which their feeding preference was assessed individually by using dual - and triple- plant choice assays. Results show both the two Helicoverpa species have a preference hierarchy for host plants. Compared to the fixed preference hierarchy of the specialist H. assulta, the generalist H. armigera exhibited extensive plasticity in feeding preference depending on the host plant experienced during larval development. Whereas the specialist H. assulta exhibited a rigid preference in both dual and triple-plant choice assays, our findings demonstrate that the generalist H. armigera expressed stronger preferences in the dual-plant choice assay than in the triple-plant choice assay. Our results provide additional evidence supporting the neural constraints hypothesis which predicts that generalist herbivores make less accurate decisions than specialists when selecting plants.

Feeding Preference of Crapemyrtle Bark Scale (Acanthococcus lagerstroemiae) on Different Species

“…As an indicator for successful reproduction, gravid female and oviposition are often used to evaluate the performance of an insect on novel hosts [ 63 , 64 , 65 ]. The varied WAI for the first gravid female found on C. speciosa , H. salicifolia, M. domestica ‘Fuji’, and M. domestica ‘Red Delicious’, suggest that the developmental times from nymph to gravid female were at least twice as long compared to L. ‘Spiced Plum’.…”

The “sequential cues hypothesis”: a conceptual model to explain host location and ranking by polyphagous herbivores

“…One solution to the “too many signals not enough processing” problem is that it is now evident that polyphagous herbivores have the capacity to detect common volatiles which arise from across their potential host ranges (Ramachandran et al ., 1990; Light & Jang, 1996; Stranden et al ., 2003; Bruce et al ., 2005; Del Socorro et al ., 2010; Bruce & Pickett, 2011; Becher et al ., 2012; Cunningham & Zalucki, 2014; Cunningham et al ., 2016; Wang et al ., 2017; Biasazin et al ., 2018), and this offers a mechanistic basis of how these herbivores locate hosts. Volatile compounds may be conserved across plant species, genera and families: for example, a small subset of pigeon pea volatiles are conserved across tobacco, cotton, and bean (Rajapakse et al ., 2006), while the green leaf volatiles (a group of several compounds) are highly conserved across the plant kingdom (Dudareva et al ., 2004; Carrasco et al ., 2015).…”

Distribution of Serotonin-Immunoreactive Neurons in the Brain and Gnathal Ganglion of Caterpillar Helicoverpa armigera

“…Feeding behavior of H. armigera larvae is mediated to a large extent by the gustatory sensillum, which detects palatable and unpalatable compounds in plants to acquire nutrients and avoid the toxins (Zhou et al, 2010). Behavioral and gustatory electrophysiological studies revealed that feeding experiences could induce changes in feeding preference of H. armigera for host plants (Zhou et al, 2010; Ma et al, 2016; Wang et al, 2017). Such feeding preference and plasticity is mediated by the signal transduction of the gustatory pathway and the modulation of the neural substance in the central nervous system (Glendinning et al, 1999, 2001).…”