Perforation index assessment of cowpea seeds against cowpea bruchid, Callosobruchus maculatus (Fabricius) [Coleoptera: Chrysomelidae], infestation using Piper guineense

Abstract

Background Powders and extracts of Piper guineense seeds and leaves were assessed for insecticidal activities against Callosobruchus maculatus in the laboratory at temperature and relative humidity of 29.6 °C and 75.9%, respectively. Bioactive compounds in P. guineense leaves and seeds were also investigated. The powders were tested at rates 1.0, 2.0 and 4.0 g/20 g cowpea seeds while extracts were tested at 1.0, 2.0 and 3.0%. Results Results of contact toxicity assay of the seed powder caused 100% adult mortality at 96 h post-treatment period whereas leaf powder evoked 90% adult mortality within the same period at concentration of 1.0 g/20 g cowpea seeds. Low adult emergence was observed on cowpea seeds treated with 1 g of seed powder with percentage adult emergence of 10.0% and inhibition rate (IR) of 97.5%. Beetle Perforation Index (BPI) obtained from treated cowpea seeds was significantly different (P < 0.05) from BPI of untreated seeds. Extracts of P. guineense seed were more toxic than seed powder. Piper guineense seed extract caused 87.5% adult mortality of C. maculatus while leaf extract caused 70.0% adult mortality within 24 h of infestation at concentration of 1%. Progeny development of C. maculatus was completely inhibited in cowpea treated with 2% and 3% leaf and seed extracts of P. guineense. β-Pinene was the most abundant active compound in P. guineense seed (55.6%) and leaf (48.4%). β-Phellandrene occurred 38.2% in seeds while Ocimene had the least value of 0.2% in seed and 0.5% in leaf. Conclusion The study showed that P. guineense seed powder and extracts were more effective than leaf powder and extract. Utilization of plant products as alternative to synthetic insecticides in protecting cowpea seeds against C. maculatus should be encouraged for enhanced food safety and security. Piper guineense is used as spice and medicine and interestingly safe for human use.

Entomotoxicity of some agro-wastes against cowpea bruchid, Callosobruchus maculatus (Fab.) [Coleoptera: Chrysomelidae] infesting cowpea seeds in storage

“…Furthermore, the powders and the ashes may also cause the inability of the insect larvae to fully cast off their old exoskeleton that typically remained linked to the posterior part of the abdomen ( Oigiangbe et al., 2010 ; Ileke, 2019 ; Ileke et al., 2020a ; b ; Obembe et al., 2020 ). The phytochemicals contained in the powder of the three agricultural wastes could also reduce adult emergence because some of the allelochemicals found in the powder of the wastes had been reported to be capable of disrupting insect life cycle ( Yang et al., 2006 ; Oigiangbe et al., 2010 ; Ileke, 2019 ; Ileke et al., 2020a ; b ; Obembe et al., 2020 ).…”

“…Agriculture is one of the oldest practices known to man and it has been the major backbone of human existence and development of many countries ( Ashamo and Ogungbite 2014 ; Ileke, 2019 ; Ileke et al., 2020a , Ileke et al., 2020b ; Obembe et al., 2020 ). Adeyemo et al.…”

“…Adeyemo et al (2013) opined that the backwardness in the agricultural sector of any country amounts to backwardness in the economic growth of such a country. Despite its relevance to human life, it has been facing a lot of challenges among which the infestation of its products by weevils and moths appears most prominent (Obembe and Ogungbite 2016;Idoko and Ileke 2020;Ileke et al, 2020b;Obembe et al, 2020). The menace of these insect pests inhibits the agricultural growth of some developing countries where insect pest management practices and government intervention in terms of efficient storage facilities are still low (Ashamo and Ogungbite 2014;Ileke et al, 2021).…”

“…The damage due to insect infestation is not only restricted to the field but also extended to the storage where they can cause more than 60% seed damage (Oni 2014;Ileke 2015Ileke , 2019Ileke et al, 2021). The multivoltine type of reproduction of the insect is a factor that compounds the problem of its infestation compared to other insect pests of cowpea (Obembe and Ogungbite 2016;Idoko and Ileke, 2020;Ileke et al, 2020b;Obembe et al, 2020).…”

Evaluation of Toxicity of Some Tropical Flora, Clay and Permethrin against Sitophilus zeamais Motsch. on Stored Maize Grains

“…Subsequently, the weight of maize grains in each vial was taken pre-and post-experiment and the weight loss due to S. zeamais infestation was noted. The weevil perforation index (WPI) assessed by counting the number of damaged seeds in all the experimental units at 60 DAT was determined using the formula adopted by Ileke et al (2020) as in Equation 1.…”