Silencing tyrosine hydroxylase or dopa decarboxylase gene disrupts cuticle tanning during larva‐pupa‐adult transformation in Henosepilachna vigintioctopunctata

Abstract

BACKGROUND: The 28-spotted potato ladybird, Henosepilachna vigintioctopunctata, is a notorious defoliator of many solanaceous and cucurbitaceous plants. Tyrosine hydroxylase (TH) and dopa decarboxylase (DDC) are responsible for cuticle tanning pathway in insects.RESULTS: We identified HvTH and HvDDC in H. vigintioctopunctata, and found that high levels of them were accumulated just before or right after molting. Injection of dsHvTH or feeding 3-iodo-tyrosine (3-IT) at the third instar larval stage repressed tanning of the larval cuticle, reduced larval feeding, inhibited larval growth, and consequently caused 100% of larval mortality. Knockdown of HvDDC at the third instar larval stage hardly affected the coloration of larval head, and partially inhibited pigmentation of larval bodies and around 80% of the HvDDC RNAi larvae developed into albino pupae and adults. Moreover, depletion of HvTH or HvDDC at the fourth instar larval stage resulted in albino pupae and adults. The HvTH or HvDDC hypomorph adults fully or partially failed to remove the larval/pupal exuviae, possessed pale and abnormal wings, and poorly tanned heads and bodies, and eventually, struggled for several days without feeding on leaves before death.CONCLUSION: These results show that TH and DDC play key roles in larval and adult cuticle tanning and development in H. vigintioctopunctata. Also, these findings suggest that dopa-and dopamine-originated pigments are essential for larval and adult feeding behavior and the molting process during emergence.

A comparative study revealed hyperspectral imaging as a potential standardized tool for the analysis of cuticle tanning over insect development

“…The most common method of cuticle analysis to assess phenotypic changes involves qualitative visual picture observations [ [13] , [14] , [15] , [16] , [17] ]. This empirical observation is limited to changes that the human eye can detect, leading to a risk of missing important information, user error and assertion bias.…”

Dusky-like Is Critical for Morphogenesis of the Cellular Protuberances and Formation of the Cuticle in Henosepilachna vigintioctopunctata

“…The larvae have two types of extensions. Firstly, an H. vigintioctopunctata larva has 11 rows of dark-branched spines (scoli) located on brown epidermal mastoids (strumae) [ 10 ], similar to its sibling species [ 11 ]. Secondly, sensory setae are located on the larval mouthparts and legs, the pupal thorax, and the adult mouthparts and elytra.…”

“…Secondly, sensory setae are located on the larval mouthparts and legs, the pupal thorax, and the adult mouthparts and elytra. Furthermore, H. vigintioctopunctata is sensitive to RNA interference (RNAi) [ 10 , 12 , 13 , 14 , 15 ]. This offers an ideal insect model to investigate the roles of Dyl throughout the entire lifecycle.…”

Challenges and opportunities in managing pests of potato

“…Four of the research papers in this issue are on the 28‐spotted potato ladybird, Henosepilachna vigintioctopunctata , which is a notorious defoliator of many solanaceous and cucurbitaceous plants; those papers summarize new progress on the tools to effectively manage H. vigintioctopunctata 13–16 …”

“…Four of the research papers in this issue are on the 28-spotted potato ladybird, Henosepilachna vigintioctopunctata, which is a notorious defoliator of many solanaceous and cucurbitaceous plants; those papers summarize new progress on the tools to effectively manage H. vigintioctopunctata. [13][14][15][16] Damage by the potato tuber moth Phthorimaea operculella (PTM) is another major constraint to commercial production of potatoes in many areas of the world. Insect sex pheromones can provide a novel pathway for the detection and monitoring of PTM.…”