Abstract
BackgroundSeaweeds harbour a wide array of bioactive compounds shown to be effective in support of sustainable agricultural practices. The green seaweed Chaetomorpha antennina found in abundance in coastal areas of India has been reported with various bioactivities. Owing to the requirement of alternative and economical natural pest control method to be applied in sustainable agronomic strategies, the current study attempts to evaluate the efficacy of chemical toxins from C. antennina, as insecticidal agents, by inspecting their effects on the physiology, biochemistry, immune system, and histology of one of the most important insect pests of agricultural crops in the Asian tropics, the polyphagous lepidopteran Spodoptera litura.ResultsThe active fraction 5 isolated from C. antennina using methanol extraction produced significant mortality rates of S. litura among all the other fractions obtained. GC–MS analysis revealed the presence of various pesticide compounds. The toxin compounds (active fraction 5) were found to negatively influence the pest’s immune system performance at sub-lethal concentrations (LC50 38.73and LC90 53.60 ppm), affecting insect development, reducing the haemocyte count (69.24%) and reduced the activity of major defence enzyme phenoloxidase decreased post-treatments. Digestive phosphatase enzymes, acid phosphatase, ACP, alkaline phosphatase, ALP, and ATPase were demodulated by 37.5, 39, and 23.9% compared with untreated. Increase in detoxification enzymes coupled with mid-gut collapse are indicative of the toxicity of the compounds. Earthworms exposed to seaweed compounds displayed no debarring effects.ConclusionExtracted seaweed compounds produced significant lethal effect on the insect larvae, affecting the immune as well as digestive systems of the pest. However, no such toxicity was observed in earthworms treated with the seaweed fraction supporting their environmentally benign nature. Since the insect immune system is responsible for the development of resurgence against pesticides, suppression of immunological activities by seaweed toxins indicate the long-term applicability of these compounds as prospective pesticides. The results support the potential of chemicals from C. antennina for biopesticide development to manage economically important agricultural pests.
Highlights
Seaweeds harbour a wide array of bioactive compounds shown to be effective in support of sustain‐ able agricultural practices
The results support the potential of chemicals from C. antennina for biopesticide development to manage economically important agricultural pests
The marine algae are a rich source of a wide variety of bioactive compounds, that have been developed into biofuels, medicines, fertilizers, plant growth stimulants, and biopesticides to name a few [1,2,3,4,5] and are considered an under-utilized ocean resource
Summary
Seaweeds harbour a wide array of bioactive compounds shown to be effective in support of sustain‐ able agricultural practices. Owing to the requirement of alternative and economical natural pest control method to be applied in sustainable agronomic strategies, the current study attempts to evaluate the efficacy of chemical toxins from C. antennina, as insecticidal agents, by inspecting their effects on the physiology, biochemis‐ try, immune system, and histology of one of the most important insect pests of agricultural crops in the Asian tropics, the polyphagous lepidopteran Spodoptera litura. Marine ecosystem organisms harbour a wide array of bioactive compounds. Among these are a group of macroalgae referred to collectively as seaweeds, which are a collection of marine plants, existing along the world’s coastlines. In addition to offering an environmentally benign and safe means of pest control, biopesticides could surpass the development of pest resurgence as well as propose a pronounced aptitude in regulating yield loss deprived of conceding the quality of the produce [18]
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