feeding assay to evaluate the effects of quercetin on helicoverpa armigera growth and development

Helicoverpa armigera Üzerindeki Fitokimyasal Etkilerin Besleme Testi ile Değerlendirilmesi

The biotic factors that affect crop productivity are mainly pathogenic agents and pests. Several insect pests cause 15% to 35% of agricultural crop loss and affect economic sustainability practices1. Insects belonging to the orders Coleoptera, Hemiptera, and Lepidoptera are the major orders of devastating pests. The highly adaptive nature of the environment has benefited lepidopterans in evolving several survival mechanisms. Amongst lepidopteran insects, Helicoverpa armigera (Cotton bollworm) can feed on around 180 different crops and cause significant damage to their reproductive tissues2. Worldwide, H. armigera infestation has resulted in a loss of around $5 billion3. Cotton, chickpeas, pigeon peas, tomatoes, sunflowers, and other crops are hosts for H. armigera. It completes its lifecycle on different parts of host plants. Eggs laid by female moths get hatched on the leaves, followed by their feeding on vegetative tissues during larval stages. The larval stage is the most destructive due to its voracious and highly adaptable nature4,5. H. armigera shows a global distribution and encroachment to new territories due to its remarkable attributes, such as polyphagy, excellent migratory abilities, higher fecundity, strong diapause, and the emergence of resistance to existing insect control strategies6.
Diverse chemical molecules from terpenes, flavonoids, alkaloids, polyphenols, cyanogenic glucosides, and many others are widely used for the control of H. armigera infestation7. However, frequent application of chemical molecules imparts adverse effects on the environment and human health due to the acquisition of their residues. Also, they show a detrimental effect on various pest predators, resulting in an ecological imbalance8,9. Therefore, there is a necessity to investigate safe and eco-friendly options for chemical molecules of pest control.
Natural insecticidal molecules produced by plants (phytochemicals) can be used as a promising alternative to chemical pesticides. These phytochemicals include various secondary metabolites belonging to the classes alkaloids, terpenoids, and phenolics7,10. Quercetin is one of the most abundant flavonoids (phenolic compound) present in various grains, vegetables, fruits, and leaves. It shows feeding deterrent and insecticidal activity against insects; also, it is not harmful to natural enemies of pests11,12. Thus, this protocol demonstrates the feeding assay using quercetin to assess its toxic effect on H. armigera.
Various bioassay methods have been developed to evaluate the effect of natural and synthetic molecules on an insect&#39;s feeding, growth, development, and behavioral patterns13. Commonly used methods include the leaf disk assay, choice feeding assay, droplet feeding assay, contact assay, diet covering assay, and obligate feeding assay13,14. These methods are classified based on how pesticides are applied to insects. The obligate feeding assay is one of the most commonly used, sensitive, simple, and adaptable methods to test probable insecticides and their lethal dose14. In an obligate feeding assay, the molecule of interest is mixed with an artificial diet. This provides consistency and control over the diet composition, generating robust and reproducible results. Important variables affecting feeding assays are the developmental stage of the insect, choice of insecticide, environmental factors, and sample size. The duration of the assay, interval between two data recordings, frequency and amount of diet fed, health of insects, and handling skill of operators can also influence the outcome of feeding assays14,15.
This study aims to demonstrate the obligate feeding assay to evaluate the effect of quercetin on H. armigera survival and fitness. Assessment of various parameters, such as insect body weight, mortality rate, and developmental defects, will provide insights into the insecticidal effects of quercetin. Meanwhile, measuring nutritional parameters, including the efficiency of conversion of ingested food (ECI), efficiency of conversion of digested food (ECD), and approximate digestibility (AD), will highlight the antifeedant attributes of quercetin.

Yazar Spotlight: Böcek Haşere Yönetimi için Besleme Deneylerinin Geliştirilmesi ve Zorlukları 

Fitokimyasalların Helicoverpa armigera Üzerindeki İnsektisidal Etkisinin Değerlendirilmesi için Beslenme Deney Sistemi Geliştirilmesi

This study is conducted to develop a simple and cost-effective feeding assay method for evaluating the effect of various natural molecules, including phytochemicals for their antifeedant and insecticidal properties against thieving insects, and identified potential molecules from these assay can be evaluated in field condition for pest management. Multiple assays have been developed to evaluate the effect of synthetic and natural molecules on insect feeding, growth, development, and behavior, further assays have been designed, such as dip case tool, diet covering assay, contact assay, droplet feeding assay, choice feeding assay, and lip dish test for insecticide evaluation, Maintaining uniform experimental conditions, addressing issues, like infection and cannibalism, ensuring even phytochemical distribution in larval diet, tracking, feeding behavior accurately, and determining optimal phytochemical concentrations post challenges, batch variation, and experimental design complexities must be managed. Additionally, transitioning from the lab assist to the field application, considering formulation and scalability is demanding.In the obligatory feeding assay, a large number of molecules can be tested simultaneously with a large number of insect sample sizes. The advantage of this feeding assay is that the test compound is mixed with an artificial diet, thus we have control over diet composition, which provides robust and reproducible results.

Watch this Scientific Journal Video about Feeding Assay to Evaluate the Effects of Quercetin on Helicoverpa armigera Growth and Development at JoVE.com

Feeding Assay to Evaluate the Effects of Quercetin on Helicoverpa armigera Growth and Development  

Quercetin'in Helicoverpa armigera Büyüme ve Gelişimi Üzerindeki Etkilerini Değerlendirmek için Beslenme Testi

Başlamak için, Helicoverpa armigera yenidoğanlarını böcek kültürü odasında müslin bezle kaplı plastik üreme odasında tutun. Daha sonra yeni ortaya çıkan yenidoğanları ince bir boya fırçası kullanarak büyümek için taze hazırlanmış, nohut bazlı yapay bir diyetle nazikçe aktarın. Beslenme tahlili için, kontrol ve tedavi seti için 21 saniye instar larvası toplayın.Önceden hazırlanmış kontrol ve quercetin içeren diyeti küçük parçalara ayırın ve diyetin ve böceğin vücudunun ağırlığını kaydedin. Böceği dikkatlice kültür şişesine aktarın, ilgili diyeti şişeye ekleyin ve böceğin beslenmesine izin verin. İkinci günden 10. güne kadar, böcek vücudunun ağırlığını ve ardından belirli bir diyet, yenmemiş diyet ve frass kaydedin.10. günde canlı ve ölü larvaları ve pupaları sayın. Verileri kaydetmek ve analiz etmek için, bir öğrenci t testi kullanarak kontrol ve tedavi grupları arasındaki böcek vücut ağırlığını karşılaştırın Canlı ölü larva ve pupa sayısını kullanarak grafik yazılımını kullanarak hayatta kalma yüzdesi için bir Kaplan-Meier eğrisi çizin. Ardından pupa yüzdesini hesaplayın ve larva gelişimi ile beslenme indekslerini karşılaştırın.Bu çalışmada, quercetin içeren diyetle beslenen böcek larvaları, kontrol grubuna göre anlamlı bir azalma göstermiş ve böylece vücut boyutlarında azalma görülmüştür. Ayrıca, quercetin ile beslenen larvaların beslenme hızında kontrole kıyasla kayda değer bir azalma gözlenmiştir. Ayrıca, kuersetinle beslenen larvalarda pupa yüzdesinde önemli bir azalma vardı ve bu da tedavi sonrası gelişimsel geriliği düşündürdü.Quercetin içeren diyetle beslenen böcekler için, yutulan gıdanın vücut maddesine dönüştürülmesinin etkinliği, kontrole kıyasla yaklaşık% 9 oranında azalmıştır. Sindirilmiş gıdaların dönüşüm etkinliği, kontrole kıyasla yaklaşık% 49 oranında azalmıştır. Kuersetin ile beslenen böceklerde yaklaşık sindirilebilirlik, kontrole kıyasla% 5 oranında artmıştır.

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Research

JoVE Journal

Biology

Feeding Assay to Evaluate the Effects of Quercetin on Helicoverpa armigera Growth and Development

71 Views.  CSIR-National Chemical Laboratory. To begin, keep Helicoverpa armigera neonates in the plastic breeding chamber covered with a muslin cloth in the insect culture room. Then gently transfer newly emerged neonates using a fine paintbrush on a freshly prepared, chickpea based artificial diet for growth. For the feeding assay, collect 21 second instar larvae for the control and treatment set.Cut previously prepared control and quercetin containing diet into small pieces, and record the weight of the diet and the insect's bo...