Survivability and nutrient composition of African palm weevil (Rhyncophorus phoenicis Fabricius) reared on five different agro-products

Abstract

African palm weevil larvae (APWL) (Rynchophorus phoenicis F.), a relished traditional food but major pest of oil palm, coconut, raffia palm, sago palm and occasionally sugarcane causes death and economic loss of these plants. Availability of feedstock is crucial for sustainable insect production however, nutrient, palatability and cost of ingredients is also essential. Thus, the need to develop nutrient efficient and cost-effective feed substrates to produce industrially safe insects. Four hundred (400) pieces third instar of APWL from the wild in Igbokoda, Ondo state, Nigeria, weighing 0.8-1.5 g were placed in perforated plastic cages, and fed palm yolk for 48 hours. After acclimatization, similar weights larvae were allotted to five substrates (palm yolk + sugarcane, young unripe coconut husk, sugarcane, honey syrup, water melon) in a completely randomized design with four replicates (n=20). After 30 days, adult insects were placed together (1 male: 5 females) and eggs laid fed dietary treatments ad libitum for 12 weeks. Survivability, weight, proximate and mineral (larvae), length, width and circumference (adult) from treatment with highest survivability were assessed. Data were analyzed by ANOVA at p<0.05. Larvae (young unripe coconut husk) had 91.25% survivability and significantly higher (p<0.05) than 68.75% (PalmYolk+Sugarcane), 38.75% (sugarcane), 38.75% (water-melon) and 18.75% (honey-syrup). Larvae weighed 8.10 g, contain 63.41% (moisture), 2.20% (ash), 12.17% (crude protein), 18.45 mg/g (sodium), 5.00 mg/g (iron), 2.42 mg/g (copper), 0.02 mg/g (calcium), 0.04 mg/g (magnesium) and 0.13 mg/g (phosphorus). The adult body was 4.20 cm (length), 2.02 cm (width) and 5.40 cm (circumference). The study highlighted that Palm weevil larvae can be reared on artificial feed substrates. Larvae and adult insects performed best on young unripe coconut husk.