Effect of rice variety on reproductive success and grain consumption of maize weevils, Sitophilus zeamais (Coleoptera: Curculionidae): a preliminary study
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Date
2024-11-01
Authors
Patabendige, A. P. K. Y.
Wanasinghe, W. M. T. D.
De Silva, W. A. P. P.
Weeraratne, T. C.
Journal Title
Journal ISSN
Volume Title
Publisher
Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka
Abstract
Sitophilus zeamais (Motschulsky, 1855), commonly known as the maize weevil, is a destructive pest that frequently occurs in stored grains, including rice. The substrate variety
can affect the reproductive success and population dynamics of these pests. The aim of this study was to investigate the effect of rice variety on the reproductive success of S. zeamais
and to evaluate the rate of consumption of rice by S. zeamais. The eleven rice varieties in Sri Lanka, including four organic and seven non-organic, were used. Three pairs of newly
emerged S. zeamais were introduced into 20 g of disinfected rice of each variety per replicate (3 replicates per rice variety) and observed for one month. Except for “Suwandal”
(9 individuals), the total number of weevils in organic rice was relatively high, with an average of 72, 53, and 18 from “Kuruluthuda”, “Pachchaperumal”, and “Maavi”,
respectively. The highest average weight loss of organic grains was observed in “Kuruluthuda” (4.64%). Regardless of the progeny size, the weight loss in
“Pachchaperumal” and “Maavi” was almost similar (~ 2.5%). The results revealed that the reproductive success of S. zeamais was low in non-organic varieties compared to organic
(p = 0.019), except “Samba”, which showed a considerable population after one month (n = 9 weevils) with 0.36% weight loss. The total number of weevils observed in “Red-raw
rice”, “White-basmati”, and “Naadu” were 7, 7, and 6, respectively. No population increase was reported in “Red-basmati”, “Keerisamba”, and “White-raw rice”. Except for Samba, a
non-considerable grain weight increase was observed in “White-basmati” (2.27%) and “White-raw rice” (1.34%), suggesting that the weight increase was due to the eggs laid by
the introduced weevils. The study suggested that the organic rice varieties are more vulnerable to S. zeamais attacks, and chemicals used for storing grains delay the reproduction
of S. zeamais.
Description
Keywords
Organic rice , Reproduction , Rice varieties , Sitophilus zeamais
Citation
Proceedings of the Postgraduate of Institute of Science Research Congress (RESCON) -2024, University of Peradeniya, P 173