USC ID: 8870
LAB SECTION: 13148
1
Effects of Sunflower Oil on Callosobruchus maculatus Oviposition
Introduction
The cowpea (Vigna unguiculata) is an herbaceous legume that is as a major source of
food in the warm regions of Africa, Asia, and the Americas 1-3. Serving as an important crop in
distribution channels throughout the world, the cowpea is also a major source of income for
farmers and vulnerable populations in these regions 1-3.
Unfortunately, the postharvest storage of the cowpea is constrained by seed infestation,
posing a major problem for farmers, traders, and those who rely on the crop for food and income.
Bruchids, among of which is the pest Callosobruchus maculatus, are primarily responsible for
cowpea infestations 4,5. Callosobruchus maculatus, also known as the “bean beetle” or “cowpea
weevil”, thrives in moderate temperatures with limited water supply. Largely due its resistance to
the environment and its resourcefulness, Callosobruchus maculatus can lay its eggs on the
cowpeas’ bean coats and allow its larvae to burrow deep into the seeds, resulting in significant
reductions in seed weight and germination 4,5. Callosobruchus maculatus is therefore extremely
detrimental to the long-term storage of cowpeas, with countries such as Nigeria reporting 70%
infestation and 30% weight loss in crops stored for six months 5. This postharvest deterioration
of the cowpea not only creates major obstacles for local farmers and traders but also results in
much larger economic losses for countries like Nigeria.
Chemical insecticides have been proposed as a cheap and effective means of combating
these pests 4,5. However, the use of these chemical insecticides has been found to be hazardous to
humans and the environment 4,5. Insects may also develop a resistance to these insecticides,
further compounding the issue 4,5. Therefore, alternatives to chemical insecticides, such as the
use of biological control, hermetic storage, and plant extracts have been proposed 5-8. Plant
USC ID: 8870
LAB SECTION: 13148
2
Figure 1. The basic layout of the Petri dish, containing
Quadrants A, B, C, and D, is shown above.
extracts, and specifically sunflower (Helianthus annuus) seed oil, appear to be especially
promising 7,8. The strategy of using vegetable oils, such as sunflower oil, as a biopesticide is not
harmful to the environment and is more accessible to poorer farmers, making it an attractive
approach for controlling Callosobruchus maculatus 8. While research has already been
conducted on the efficacy of such oils against the growth and development of the progeny of
Callosobruchus maculatus 8, little research has been conducted on whether such oils, and
specifically sunflower oil, can inhibit the oviposition of Callosobruchus maculatus on cowpeas.
We hypothesize that sunflower seed oil, through its inhibition of the oviposition of
Callosobruchus maculatus, can be used as effective pest control against the beetle. To test our
hypothesis, we propos...
