Abstract
In the study reported herein, we aimed to isolate a trypsin inhibitor from Ricinus communis leaves through chromatographic and spectrometric techniques and evaluate its toxic effects on the development of Spodoptera frugiperda larvae. Plant extracts were submitted to fractionation in adsorption column. The fraction 10, which showed the highest inhibitory activity, were incorporated into an artificial diet at the concentrations of 0, 0.06, 0.12, 0.25 and 0.5%, and offered to S. frugiperda larvae. Fresh weight of larvae, food consumed and weight of eliminated faeces were registered. Based on these parameters the following nutritional index were calculated: Relative Consumption Rate (RCR), Relative Metabolic Rate (RMR), Relative Growth Rate (RGR), Approximated Digestibility (AD), Efficiency of Ingested Food Conversion (EIC), Efficiency of Digested Food Conversion (EDC) and the Metabolic Cost (100 - EDC). The inhibitor at 0.5% concentration was deleterious to S. frugiperda, extending the larval stage in 11 days, with higher RCR and ECD, and lower RGR, ECI and ECD. Therefore, the trypsin inhibitor from leaves of R. communis affected the S. frugiperda larval development, being promising in studies of alternative and sustainable control methods for lepidopteran pest species. Key words: Castor beans, enzymatic inhibition, integrated pest management, plant defense against herbivory.  
Highlights
The fall armyworm, Spodoptera frugiperda (Smith, 1797) (Lepidoptera: Noctuidae), is one of the most important insect pest of maize in Brazil, attacking the plant at different growth stages, when the larvae burrow into the plant whorl causing severe defoliation and 37% loss in production (Cruz, 2002)
Leaves of R. communis were collected in a field located in Lavras County (21°13’29.73’’ S; 49°58’43.93’’ W ) state of Minas Gerais, Brazil, and the voucher specimen was deposited in the herbarium of the Federal University of Lavras (UFLA)
Trypsin inhibitors are extensively studied in several aspects aiming biochemistry characterization, three dimensional structures, interactions with multiple protease classes and effects on pests and pathogens (Abd El-Latif, 2014; Kuwar et al, 2015; Pontual et al, 2014; Zhu-Salzman and Rensen, 2015)
Summary
The fall armyworm, Spodoptera frugiperda (Smith, 1797) (Lepidoptera: Noctuidae), is one of the most important insect pest of maize in Brazil, attacking the plant at different growth stages, when the larvae burrow into the plant whorl causing severe defoliation and 37% loss in production (Cruz, 2002). A promising alternative to control fall armyworm is the use of plants secondary metabolites (Tavares et al, 2009; Alves et al, 2014) These chemicals compounds produced by plants can induce deleterious effects on insects such as weight loss, fecundity and fertility reduction, increasing duration of immature stages, feeding deterrence, ultra structural modification on tissues, changes in some nutritional parameters, and inhibition of digestive enzymes, which is lethal to some insects (Malau and James, 2008; Nathan et al, 2008; Correia et al, 2009). Levels of PIs in plant leaves are usually low and can be increased to high levels if the plants are attacked by insects, suffer mechanical damage or exposed to plant hormones (Rakwal et al, 2001)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
