Insecticidal effects of neem seed oil (Azadirachta indica) extract against insect pests of stored cocoa (Theobroma cacao), ginger (Zingiber officinale) and sesame (Sesamum indicum)

Abstract :

Storage insect pest is a major constraint to stored produce in Nigeria. The insecticide properties such as low toxicity to non-target organism, biodegradability, environmentally friendliness and high volatility makes essential oils better alternatives to conventional fumigants in the control of storage pest. Thus, the study aimed to assess insecticidal effect of Neem (Azadirachta indica) seed oil (NSO) on insect pests and weight of cocoa bean, ginger rhizome and sesame seed in storage. Cocoa, Ginger and Sesame samples were randomly collected once a month for three months from Oba Akran, Ogba, Isolo and Ijora in Lagos and Imeko and Idiroko warehouse in Ogun State. Each produce (100g) in jars were kept for 1 month in a dark cupboard for insect emergence. Identity of emerged insect and mite were confirmed at Insect Reference Centre, University of Ibadan. NSO applied on cotton wool at 0.1ml, 0.2ml and 0.3ml was suspended inside jar containing each produce (100grams) following standard procedures, arranged in a completely randomized design in three replicates. Data were taken on storage insect pest population, mortality and weight of stored produce at monthly interval for six months, then data were analysed using ANOVA and significant means separated with Least Significant Difference at P≥0.05. Cocoa beans had highest number (10) of storage pests, ginger (6) and sesame seed had only Trogoderma granarium and two mites (Tyroqulyphus farina and Polypharqotarsonernus latus). Lasioderma serricone and Tribolium castaneum infested cocoa and ginger while Trogoderma granarium attack ginger and sesame. There were significant differences (P<0.05) in number of live insects between NSO treatment in cocoa (0) and control (5.33) at first month of storage. Number of insects between neem (0.1ml and 0.2ml) and control were significantly different (P<0.05) from 0.3ml neem oil at first month of storage but from 4th to 6th month, number of live insect in control and neem oil was not significantly  different in cocoa. Neem seed oil used as fumigant was able to reduce infestation of insect pests for three month only with progressive loss in seed weight as storage period increased. This means that repeated application is needed after 3 months of storage.

Keyword :

Stored products, neem oil, cocoa, ginger, sesame pest

Author(s) : Joda, A. O., Akagu, A. A., Ademolu, K. O., Oguntade, O. A.
Downloads : 15
Published Issue : 2023 Vol. 18 Number 1

2023 Vol. 18 Number 1