The emergence of supermarkets may provide an alterative avenue through which vegetables can move from the producer to the consumer. To date, no research has been conducted to determine the functions of vegetable supply chains of supermarkets in Sri Lanka. This study aimed to fill this gap while ascertaining whether the emergence of supermarkets has created vegetable supply chains that are different from existing traditional supply chains and if so, to examine whether such alternative supply chains are comparatively more efficient and effective. The research was conducted in the form of Case studies. To establish the existing supermarket related vegetable supply chains, supermarkets were selected using the purposive sampling technique. A sample of actors involved in a given supermarket supply chain was chosen via the Snowball sampling technique. The findings of the study revealed that supermarkets do create alternative supply chains of vegetables; however, these alternative supply chains are created only with respect to supermarkets with a large number of outlets. Such supply chains deem to be comparatively more efficient and effective than traditional supply chains in terms of paying a higher price for vegetables, having a higher degree of transparency, presence of quality consciousness and accountability, passing down of quality signals, involvement of less number of intermediaries and occurrence of comparatively low post harvest losses. In some locations, the emergence of the particular supermarket supply chain has contributed to increase the level of competition among buyers leading to an increase in the farm gate price offered by the traditional supply chains. However, the benefits yielded by the farmers vary depending on the context. Due to the uncertainty in relation to price and quantity, farmers were not motivated to improve their production practices. At present, the amount of vegetables passing through supermarket supply chains deem to be comparatively very low, thus the policy focus should be to improve the efficiency and effectiveness of traditional supply chains while aiding farmers to better integrate with these new markets.
Rice leaf folder, Cnaphalocrocis medinalis is a major pest, in many rice growing areas of Sri Lanka. Biological control of this pest is encouraged due to ill effects of insecticide application on rice ecosystem. Use of egg parasitoids is advantageous over larval and pupal parasitoids, as they could destroy pests at the egg stage. Trichogrammatoidea bactrae present in rice fields in Sri Lanka, is an egg parasitoid of rice leaf folder. This study was conducted to assess the potential of T. bactrae as a biocontrol agent for the management of rice leaf folder. T. bactrae was reared on Cocyra cephalonica and its fecundity, longevity and parasitism were assessed. Acceptance of stored host eggs and parasitoid emergence from stored parasitized eggs were examined. Dispersal ability of parasitoid was also examined. T. bactrae adults showed a mean longevity of 7.9 days (range 1-15 days) and laid 55 eggs / female during first 5 days; of which, 56 % of eggs was laid on the first day. There was a significant reduction (F=5.26; df=14; 89; P< 0.001) in parasitism, 66-35 %, with increasing number of generations on C. cephalonica. Parasitism steadily decreased as the number of generations increased. Acceptance of C. cephalonica eggs varied significantly with temperature (F=187 df=1; 126 P<0.001). Mean acceptance at 4 and 8 ºC was 30 and 42 % respectively. Acceptance also significantly varied with the duration stored (F=385; df=6; 126; P<0.001). Parasitized eggs of T. bactrae could be successfully stored under low temperature (4 ºC) up to 40 d. Over 80 % parasitism was achieved with 150 parasitoids released within 25 cm radius circle. Hence, T. bactrae is a promising candidate to be promoted as a biocontrol agent of C. medinalis.
Use of egg parasitoids is an effective option available for managing lepidopteran pest species through augmentation and release of the parasitoids, particularly the locally available species. As the local egg parasitoids in Sri Lanka are poorly studied, an investigation was conducted to identify the egg parasitoids associated with rice leaf folder (Cnaphalocrocis medinalis Guenee) and cabbage semilooper (Trichoplusia ni Hubner). The host eggs were collected in different geographical locations for different durations in rice (Oryza sativa L.) and cabbage (Brassica oleracea L.) fields. The eggs were incubated until the emergence of host larvae or the adult parasitoid. Emerged parasitoids were preserved in 70% ethanol and subsequently dissected for male genitalia and the permanent slides were prepared using Canada balsam as the mounting media. Identification of specimens was done using taxonomic keys and related literature. Identities were confirmed by the Natural History Museum, London. Two species namely, Trichogramma chilonis Ishhi and T. achaeae Nagaraja and Nagarkatti were found parasitizing T. ni at Dodangolla and Thalatuoya regions in Sri Lanka. The record of T. achaeae is the first country report and T. chilonis had been recorded previously in Sri Lanka. The morphology of male genitalia was described and compared with the original description. Trichogrammatoidea bactrae Nagaraja and T. nana Zehnter were found parasitizing C. medinalis eggs at six sampling sites. The male genitalia of these two species were characterized and compared with the original descriptions.
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