Diet choice: The two-factor host acceptance system of silkworm larvae

AbstractOligophagous insect herbivores specifically identify host-plant leaves using their keen sense of taste1. Plant secondary metabolites and sugars are key chemical cues for insects to identify host plants and evaluate their nutritional value, respectively2. However, it is poorly understood how the insect chemosensory system integrates the information from various gustatory inputs. Here we report that a two-step chemosensory system is responsible for host acceptance by larvae of the silkworm Bombyx mori, a specialist for several mulberry species. The first step controlled by a gustatory organ, the maxillary palp (MP), is host-plant recognition during palpation at the leaf edge. Surprisingly, MP detects chlorogenic acid, quercetin glycosides, and β-sitosterol, which stimulate feeding by the silkworm3–6, with ultra-sensitivity (thresholds of aM to fM). Detecting a mixture of these compounds triggers test biting. The second step is evaluation of the sugar content in the leaf sap exuded by test biting. Low-sensitivity chemosensory neurons in another gustatory organ, the maxillary galea (MG), mainly detect sucrose in the leaf sap exuded by test biting, allowing larvae to accept the leaf and proceed to persistent biting. Our present work shows the behavioral and neuronal basis of host acceptance in the silkworm, mainly driven by six phytochemicals. It also reveals that the ultra-sensitive gustation via MP strictly limits initiation of feeding in the silkworm unless it detects a certain combination of host compounds, suggesting an essential role of MP in host-plant selection. The two-step chemosensory system reported herein may commonly underlie stereotyped feeding behavior in phytophagous insects and determine their feeding habits.

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Faculty Opinions recommendation of Retaliatory mafia behavior by a parasitic cowbird favors host acceptance of parasitic eggs.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1069804.522739 ◽

2007 ◽

Author(s):

Michael Siva-Jothy

Keyword(s):

Host Acceptance

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The small molecule ZY-214-4 may reduce the virulence of Staphylococcus aureus by inhibiting pigment production

BMC Microbiology ◽

10.1186/s12866-021-02113-5 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Jingyi Yu ◽

Lulin Rao ◽

Lingling Zhan ◽

Bingjie Wang ◽

Qing Zhan ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Survival Rate ◽

Small Molecule ◽

Quantitative Polymerase Chain Reaction ◽

Inhibitory Effect ◽

Pigment Production ◽

Silkworm Larvae ◽

Pigment Synthesis ◽

Polymerase Chain ◽

Oxidant Sensitivity

Abstract Background In recent years, clinical Staphylococcus aureus isolates have become highly resistant to antibiotics, which has raised concerns about the ability to control infections by these organisms. The aim of this study was to clarify the effect of a new small molecule, ZY-214-4 (C19H11BrNO4), on S. aureus pigment production. Results At the concentration of 4 μg/mL, ZY-214-4 exerted a significant inhibitory effect on S. aureus pigment synthesis, without affecting its growth or inducing a toxic effect on the silkworm. An oxidant sensitivity test and a whole-blood killing test indicated that the S. aureus survival rate decreased significantly with ZY-214-4 treatment. Additionally, ZY-214-4 administration significantly reduced the expression of a pigment synthesis-related gene (crtM) and the superoxide dismutase genes (sodA) as determined by real-time quantitative polymerase chain reaction (RT-qPCR) analysis. ZY-214-4 treatment also improved the survival rate of S. aureus-infected silkworm larvae. Conclusions The small molecule ZY-214-4 has potential for the prevention of S. aureus infections by reducing the virulence associated with this bacterium.

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Assortments of Digestive Enzymes Induced in First Instar Larvae of Busseola fusca Feeding on Different Plants

International Journal of Insect Science ◽

10.1177/1179543319843521 ◽

2019 ◽

Vol 11 ◽

pp. 117954331984352 ◽

Cited By ~ 1

Author(s):

Gérald Juma ◽

Bruno Le Ru ◽

Paul-André Calatayud

Keyword(s):

Plant Species ◽

Digestive Enzymes ◽

Host Plants ◽

Feeding Habits ◽

Busseola Fusca ◽

Stem Borer ◽

Sub Saharan Africa ◽

Host Acceptance ◽

First Instar ◽

Sub Saharan

The stem borer Busseola fusca (Fuller) (Lepidoptera: Noctuidae) is an important pest of maize and sorghum in sub-Saharan Africa. This insect has oligophagous feeding habits, feeding mostly on maize and sorghum with a narrow range of wild Poaceous plant species. We hypothesised that first instar B. fusca larvae, the critical stage for successful establishment on a host plant, can establish and then grow on a particular plant as a result of induction of a complement of digestive enzymes that mediates host acceptance at first instars. A fast semi-quantitative analysis of potentially digestive enzymatic activities present in the first larvae previously fed for 4 days on leaves of host and non-host plants was performed using the API-ZYM kit system able to detect a multiplex of enzyme activities. Regardless of the plant species, the larvae exhibited higher activities of the carbohydrate metabolising enzymes than of aminopeptidases and proteases. In addition, highest activities of carbohydrates degrading enzymes were exhibited by larvae that consumed leaves of the most preferred plant species of B. fusca. Conversely, esterases were only detected in neonate larvae that consumed leaves of the less preferred and non-host plants. No alkaline phosphatase and lipase activities were detected. The significance of these results was discussed in terms of food requirements of first instar larvae when settling on a plant.

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