Effectiveness of the Powders of <i>Securidaca longepedunculata </i> (Fres.) as Bioinsecticides against Cowpea Beetle, <i>Callosobruchus maculatus </i> (Fab.) (Coleoptera : Chrysomelidae)

Abstract

Insect pests cause a great deal of post-harvest losses of stored food products worldwide and especially in the tropics where food products are usually susceptible to attack by insects between the periods of harvest, storage and consumption. In the present study, powders obtained from different parts of Securidaca longepedunculata (Fres.) (leaf. Stem bark and root bark) were tested against the cowpea beetle, Callosobruchus maculatus in the laboratory at ambient tropical conditions of temperature and relative humidity. The powders were applied at 0.0 (control), 0.2, 0.4. 0.6. 0.8 and 1.0 g. Insect mortality was observed for four (days). The result obtained showed that mortality of the insect increased with increased in concentration and exposure time. The powder obtained from the root bark recorded the highest insect mortality of 71.25 % within 96 h of exposure at the highest dosage of 1.0 g this was followed by the stem bark causing 65 % at the same level of concentration. The LD 50 revealed the root bark powder to be the most effective as 3.17 % was required to obtain 50% insect mortality within 96 h of application as reflected by the regression probit analysis. The least toxic powder on C. maculatus was leaf powder. It was also observed that the tested powders significantly (P<0.05) reduced oviposition and percentage adult emergence when compared with the control. The results obtained from this research work showed that root bark of S. longepedunculata contains components of higher toxicity potential.

Toxicity and oviposition inhibitory effect of extract and powder of Momordica charantia leaf against Callosobruchus maculatus Fab. (Coleoptera: Chrysomelidae) on stored cowpea seed

“…Currently, synthetic insecticides are the chief means of insect pests control both in the field and in storage (Ojo et al, 2018). They have shown efficacy against a wide range of pest species of agricultural crops.…”

“…Botanical insecticides are generally pest-specific and are relatively harmless to non-target organisms. These natural insecticides have proved to be effective, biodegradable, low cost, low technological base, selective and environmentally friendly (Obembe, 2017;Adededire et al, 2011;Ojo et al, 2018). Also, the possibility of insect developing resistance to botanical insecticide is less (Scott et al, 2005).…”

Phytochemical Composition and Insecticidal Property of Native Plants against the Cowpea Weevil &lt;i&gt;Callosobruchus maculatus&lt;/i&gt; Fab. (Coleoptera: Bruchidae) for Natural Preservation of Cowpea Seeds

“…The use of these synthetic insecticides has become a threat to several ecosystems. They could also have a negative impact on predatory arthropods or parasitoids that prey on pests [8] and it is well known that resistance to these insecticides can develop rapidly [9]. This is why natural substances as alternatives, are considered effective and durable, less toxic and less polluting than synthetic insecticides [10] and give hope for several agricultural stakeholders.…”

Efficacy of Kigelia africana Lam. (Benth.) leaf and stem bark ethanolic extracts on adult cowpea seed beetle, [Callosobruchus maculatus Fabricius (Coleoptera: Chrysomelidae)] affecting stored cowpea seeds (Vigna unguiculata)

“…The cowpea seed beetle, Callosobruchus maculatus is a field-to-store pest of cowpea ( Alabi and Adewole, 2017 ). Infestation usually commences in the field and continues in the store where the population is being built up ( Ojo et al., 2018 ). C. maculatus causes a great deal of losses to stored cowpea seeds which has led to serious problems to peasant farmers all over the world ( Obembe and Ojo, 2018 ).…”

“…In order to overcome the problem of insect pests damage in the store, different control measures have been developed and used around the world. The use of conventional insecticides has been in place for many years (Ojo et al, 2018). These conventional insecticides are associated with many problems, including high persistence, poor knowledge of application by the peasant farmers, pest resurgence, genetic resistance by the insects, ozone layer depletion potential and effects on non-target organisms in addition to environmental pollution and direct toxicity to users (Adedire et al, 2011;Obembe et al, 2020).…”