BACKGROUND: Citrus sinensis, Allium sativum, Ocimum basilicum, Mentha spicata, Curcuma longa, Carica papaya, Andrographis paniculata, Azadirachta indica, Cymbopogon citratus andAcorus calamus were compared in the form of extracts of chloroform, hexane and aqueous media for their effectiveness in repelling Tribolium castaneum. Filter paper of 9 cm in diameter was cut into halves. Using a micro-pipette, each extract was applied to one half of the filter paper. The volume applied was kept constant at 0.6 mL per 30 cm 2 . The filter paper was dried and reattached leaving a 0.5 cm gap between, in a Petri-plate. Ten adults of T. castaneum were introduced and the repellency was observed after 30, 60 and 180 min. RESULTS:The aqueous extract of C. papaya exhibited the highest repellency (82-97%) followed by that of garlic bulbs (aqueous extract) with 86.67% repellency. Further, gunny bags were sprayed separately using bottle sprayers with the two most effective extracts at a constant volume of 42 mL per 575 cm 2 . These treated gunny bags were compared with malathion-treated gunny bags in the insect management unit. The observations were taken after 2, 8 and 24 h. Papaya leaf extract-treated gunny bags showed relative repellent activity similar to that of malathion-treated gunny bags after 24 h of treatment. Thus, gas chromatography-mass spectrometry analysis of aqueous extract of papaya leaves was performed. CONCLUSIONS: It can be concluded that extract of papaya leaves containing 2-methoxy-4-vinylphenol (8.47% peak area) can be used as a repellent biopesticide. Experimental designExperiments were laid out in Minitab software. Tukey's test was conducted to check the significance and determine the insecticidal plant having the highest repellency. However, before conducting statistical analysis, final data for the count of insects repelled were transformed to log(x + 1). Reported means and standard deviation are of original data, given as percentages. RESULTS Repellent effect of various extracts against T. castaneum in filter paper testEffect of chloroform extracts of insecticidal plants against T. castaneum The results showed that extracts of papaya leaves (83.3%), neem leaves (80.0%), garlic bulbs (80.0%), turmeric (76.7%), green chiretta (76.7%) and basil leaves (70.0%) at 30 min gave significant repellency (P < 0.01). Neam leaf extract gave significantly J Sci Food Agric 2020; 100: 1541-1546

BACKGROUND: The protection of grains from insect infestation is critical during storage. Insect repellent pellets (IRPs) are a potential technique to repel insects by hindering insect movement toward the grains. The basic principle of IRPs is the use of active components found in the oils of lemongrass, eucalyptus, and neem leaves for the controlled release of fumes, thereby avoiding the need for reapplication after a few days. Here, we examined the antifungal activity, the lethal dose, and the repelling effect of IRPs against red flour beetle, Tribolium castaneum, over a 30 day period. RESULTS: We observed that IRPs possessed antifungal properties and were able to repel the adults of T. castaneum. These insects ultimately died from the fumes if they manage to stay near the IRPs (LD 50 = 2 and LD 99 = 7 days). The active components (phenol, 2,4-di-tert-butyl-, citral, neral, geraniol, n-hexadecanoic acid) present in IRP during the initial stage were also found after a storage period of 35 days.CONCLUSION: The active components present in IRPs have antifungal, repellent, and fumigant properties. The IRPs can thus be termed potent botanical insecticides and are an alternative to synthetic insecticides.