Efficacy of different hermetic bag storage technologies against insect pests and aflatoxin incidence in stored maize grain

AbstractThe performance of six grain storage technologies for the control of insect pests in maize was evaluated over a 36-week (9-month) storage period. The six technologies used were: two ZeroFly® hermetic bag brands (laminated and non-laminated); Purdue Improved Crop Storage (PICS) bag; non-hermetic ZeroFly® bag; woven polypropylene (PP) bag containing maize grain treated with Actellic Gold® Dust (pirimiphos-methyl 1.6% + thiamethoxam 0.3%) and woven PP bag containing untreated grain. Each bag was filled with 50 kg maize grain and four replicates of each were set up. With the exception of the non-hermetic ZeroFly® bag, 50 live adults of the larger grain borer Prostephanus truncatus and of the maize weevil Sitophilus zeamais, were introduced into all the bags. Insects were not introduced into the non-hermetic ZeroFly® bag to assess its effectiveness in repelling infestation from outside. Parameters recorded were gas composition (oxygen and carbon dioxide) levels inside the bags; weight of flour generated by insect feeding activities; grain moisture level; live adult insect counts; grain damage and weight loss; grain germination rate and aflatoxin level. At termination, the plastic liners of the hermetic bags were examined for perforations. Results show that oxygen depletion and carbon dioxide evolution were faster in ZeroFly® hermetic compared to PICS bags. Throughout the 36-week storage trial, grain damage remained below 4% and weight loss below 3% in all the treatments except in the untreated PP bags in which it increased to 81.1 and 25.5%, respectively. The hermetic PICS, ZeroFly® and Actellic Gold dust-treated PP bags maintained grain germination at 60%, which was lower than the initial 90%, while in untreated control, it reduced to 4.7%. The mean aflatoxin levels fluctuated between 0.39 and 3.56 parts per billion (ppb) during 24 weeks of storage in all the technologies tested, which is below the acceptable maximum level of 10 ppb in maize. Based on the evaluation results, it can be concluded that hermetic PICS and ZeroFly® bags and woven PP bag with Actellic Gold dust-treated grain effectively protected stored maize grain from insect attack and weight losses. Appropriate strategies and mechanisms for the effective and efficient adoption of hermetic storage bag technology at scale would contribute towards global food security.</jats:p

Methods of screening maize for resistance to stem borers and post-harvest insect pests

This manual is based on the work undertaken through the “Developing Maize Resistant to Stem Borer and Storage Insect Pests for Eastern and Southern Africa – IRMA III Conventional Project (2009−2013)”, funded by the Syngenta Foundation for Sustainable Agriculture. We would like to acknowledge Dr B.M. Prasanna (Director, Global Maize Program, CIMMYT), for his inputs and guidance during preparation of this manual.vii, 30 page

Evaluation of Purdue Improved Crop Storage Triple Layer Hermetic Storage Bag against Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) and Sitophilus zeamais (Motsch.) (Coleoptera: Curculionidae)

Hermetic technologies are being promoted in Africa as safer and more effective methods of grain storage on smallholder farms. However, farmers and policy makers lack knowledge of their efficacy in controlling major stored grain pests. An on-station study was conducted to evaluate the triple layer Purdue Improved Crop Storage (PICS) airtight bags against two major storage insect pests. Two sets each of PICS, jute and polypropylene bags were filled with 50 kg maize grain per bag. Each set was replicated four times. One set of PICS bags was each infested with 50 insects each of the larger grain borer P. truncatus and the maize weevil S. zeamais; while the other set was not. One set of jute and polypropylene woven bags was treated with a cocktail of 1.6% Pirimiphos methyl and 0.3% Permethrin, serving as positive controls; while the remaining sets with untreated maize grain formed negative controls. Gas analysis in the PICS bags followed the expected trend with oxygen levels falling sharply below 10% and carbon dioxide increasing to almost 10% after 12 weeks hence resulting in insect death. After 16 weeks, increase in oxygen levels may be attributed to perforation of the bags from outside by the P. truncatus. Results showed that PICS bags were significantly (P &lt; 0.05) superior to treated and untreated controls of polypropylene and jute bags in suppressing insect development, maize grain damage and weight loss during storage. Weight loss in polypropylene and jute bags reached 40% and 41%, respectively, at 24 weeks after storage compared to PICS (2.4&ndash;2.9%). These results demonstrate that PICS bags can be used to store maize against P. truncatus and S. zeamais attack

Combined effect of hermetic bag and insect resistant variety for the control of larger grain borer and maize weevil in stored maize

Combined effect of hermetic bag and varietal resistance was studied for control of Prostephanus truncatus and Sitophilus zeamais. Two maize varieties: resistant (CKPH08028) and susceptible (PH3253) were used in combination with SuperGrain bag II™, PICS bag, Smartbag -1, Polypropylene bag and Actellic super dust. A mean of 5.2% Carbon dioxide for both PICS and SuperGrain II™ bags and 2.6% for Smartbag -1 were recorded. PICS and SuperGrain II™ bags suppressed insect population, prevented grain loss and cross - infestation of insects from the surrounding environment. Grain weight losses were 0.3% in the PICS and 0.9% in the SuperGrain IV-R™ bags compared to 23.9% in the polypropylene bags, 180 days after storage. No grain protection benefits were gained when either insect resistant (CKPH08028) or susceptible (PH5253) maize grains were stored in PICS or SuperGrain II™ bags (<5% damage and <1% weight loss). Synergistic benefits in protection were gained when the weight loss of CKPH08028 grains stored in either PICS or SuperGrain II™ bags were compared to that of the same variety stored in the polypropylene bags. Admixture of maize grain with Actellic super dust and storage in polypropylene bag did not prevent infliction of damage (45.6%) and weight loss (13.6%) due to insect pests. The novelty of the work is demonstrated in the potential use of hermetic bags in combination with insect resistant maize technologies to significantly reduce weight loss from 30% to less than 1% without use of pesticide. This would improve food security at household level. The findings of this study would support agricultural policy formulation and monitoring of loss reduction activities.2305-231

Evaluation of Purdue Improved Crop Storage Triple Layer Hermetic Storage Bag against Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) and Sitophilus zeamais (Motsch.) (Coleoptera: Curculionidae)

Hermetic technologies are being promoted in Africa as safer and more effective methods of grain storage on smallholder farms. However, farmers and policy makers lack knowledge of their efficacy in controlling major stored grain pests. An on-station study was conducted to evaluate the triple layer Purdue Improved Crop Storage (PICS) airtight bags against two major storage insect pests. Two sets each of PICS, jute and polypropylene bags were filled with 50 kg maize grain per bag. Each set was replicated four times. One set of PICS bags was each infested with 50 insects each of the larger grain borer P. truncatus and the maize weevil S. zeamais; while the other set was not. One set of jute and polypropylene woven bags was treated with a cocktail of 1.6% Pirimiphos methyl and 0.3% Permethrin, serving as positive controls; while the remaining sets with untreated maize grain formed negative controls. Gas analysis in the PICS bags followed the expected trend with oxygen levels falling sharply below 10% and carbon dioxide increasing to almost 10% after 12 weeks hence resulting in insect death. After 16 weeks, increase in oxygen levels may be attributed to perforation of the bags from outside by the P. truncatus. Results showed that PICS bags were significantly (P &lt; 0.05) superior to treated and untreated controls of polypropylene and jute bags in suppressing insect development, maize grain damage and weight loss during storage. Weight loss in polypropylene and jute bags reached 40% and 41%, respectively, at 24 weeks after storage compared to PICS (2.4–2.9%). These results demonstrate that PICS bags can be used to store maize against P. truncatus and S. zeamais attack.</jats:p

Mass rearing of stem borers, maize weevil, and larger grain borer insect pests of maize

Variety screening studies require a consistent supply of large quantities of these pests at specified time periods. Stem borers are reared on an artificial diet in order to have dependable large and continuous supplies of insects for screening plant materials. The stem borer and post-harvest rearing facility has a significant impact on research focused at managing post-harvest insects and maize stem borer populations through host plant resistance. The rearing facility supports national and international research projects aimed at developing maize varieties that can be incorporated in integrated pest management of stem borers and post-harvest pests of maize. This manual will describe the methods used to rear stem borers, maize weevil and larger grain borer in the facilities at KARI - Katumani and KARI - Kiboko, both in Kenya.36 page

The responses of <i>Prostephanus truncatus</i> (Coleoptera: Bostrichidae) and <i>Sitophilus zeamais</i> (Coleoptera: Curculionidae) to pheromone and synthetic maize volatiles as lures in crevice or flight traps

AbstractFlight traps and crevice traps for catching Prostephanus truncatus (Horn) and Sitophilus zeamais Motschulsky were studied in Kenya. The traps were baited with pheromones of these beetles, with or without synthetic maize volatiles. In the case of P. truncatus, which has a two component pheromone consisting of Trunc-call 1 (T1) and Trunc-call 2 (T2), the components were tested singly or in a 1:1 combination. The addition of synthetic maize volatiles to pheromone traps did not result in an increase in trap catch of either S. zeamais or P. truncatus. The pheromone of S. zeamais was an effective lure in both crevice and flight traps but the actual numbers captured were low. Captures with traps baited for P. truncatus were much greater. The response of P. truncatus to the two components of its pheromone was affected by the type of trap used. Crevice traps baited with either component alone caught fewer beetles than those baited with a mixture. In contrast, flight traps baited with T2 or the mixture were equally effective while traps with only T1 caught significantly fewer than either of these. These observations clarified apparent discrepancies between earlier studies in Tanzania and Mexico and are used to derive an hypothesis about the roles of T1 and T2; T2 appears to be a long-range attractant and T1 important for modifying the response to T2 to facilitate close-range orientation. Adult P. truncatus arriving at the traps were sexed, and in both flight and crevice traps the majority of captures were females even though in the experimental maize cribs the beetles were present in a roughly equal sex ratio. The role of the pheromone is discussed in the light of this observation.</jats:p