Study On The Damage Characteristic Of Plodia Interpunctella(Hübner) On Three Grains

The Indian meal moth,Plodia interpunctella(Hübner)which has a wide range of distribution and can damage a variety of grain and processed has a remarkable influence to social economy and food safety.Understanding the damage characteristic of Indian meal moth on different conditions can help scientifically formulate prevention and control decisions and take timely preventive and control measures.This paper studied the selective infection preference and damage status of Indian meal moth in wheat,maize and paddy,the comparison of the damage ability of Indian meal moth in environments with low oxygen and normal oxygen concentrations.The change of TKW(thousand kernel weight),IDK(insect damage kernel),FAV(free acid value)at different time after infestation with larvae of Indian meal moth with a density of 2,4,and 6 larvae per kg were measured at 20,25,and 30 °C ambient temperature and 8,11 and 14% oxygen concentrations,the main results are as follows:After placing different samples in a closed environment and releasing Indian meal moth for 2 days,the number of eggs and larvae in the samples was examined.The results showed that the numbers of larvae in wheat,corn,and rice were 10.00,18.67,and 1.33,respectively,and the number of larvae increased when the disruption rate increased.The numbers of eggs in wheat,corn and rice were 21.00,39.33,and 5.33,respectively.When the content of broken kernels in the same grain variety increased,the number of eggs in the sample increased.P.interpunctella has different damage capabilities for different food varieties.At 25 °C,cereal infected with two first star larvae per kilo of Indian meal moth.After 42 days,the TKW of wheat decreased from 44.39 g to 43.69 g,and there was a significant difference at 28 days;the IDK increased from 0.00% to 1.33% and Significant changes appeared at 42 d;FAV rose from 19.533 mg KOH /100 g to 29.46 mg KOH /100 g,which changed significantly within 7 days.The TKW of maize decreased from 316.30 g to 313.08 g after storage for 42 days,and it significantly changed at 21 days.The IDK increased from 0.00% to 1.00%.The significant difference occurred at 42 days;the FAV increased from 30.87 mg KOH/100 g to 42.87 mg KOH/100 g changed significantly at 14 days.The TKW of paddy decreased from 31.58 g to 31.36 g after storage for 42 days,but the change was not significant within 21 days.The IDK changed significantly at 42 days and increased by 1% when compared with 0d.The fatty acid values increased from 15.69 mg KOH /100 g to 16.66 mg KOH/100 g and Significant difference appeared after 35 days.Temperature,moisture content,insect population density and stored time all can affect the deterioration rate of wheat quality,and with the increasing in environmental temperature,moisture content,insect population density and prolonging of infestation time can lead to a faster rate of quality changes.Among them,the temperature effect is the most serious.The P.interpunctella mainly damage grain in larvae stage.Adjusting unsuitable environmental conditions can inhibit their feeding ability,but it also prolongs the larvae stage.In the actual storage environment,it is difficult to reduce the temperature and moisture to a level that can lead to the death of the P.interpunctella.Therefore,adjusting environmental conditions can delay the damage to the grain in a short period of time.According to the result of this experiment,under the condition of 20?,the time for significant quality change of wheat infested by P.interpunctella at the population density of 2 larvae per kilogram was 35 d,advanced to 28 d at 25?,and 14 d at 30?.When the density of P.interpunctella reach 4 larvae per kilogram,the time of appearance of the damage can be delayed to 21 d only at 20?.The quality of wheat can be remarkable changed within 7 d after the temperature rises to 25?.Although reducing the moisture content can inhibit the damage,but the effect is not obvious.Decreasing the oxygen concentration can inhibit the damage ability of P.interpunctella.The lower the oxygen concentration,the more effective the inhibitory effect is.11-14% of the oxygen concentration can inhibit the damage capability of the P.interpunctella,but it can still cause significant changes in IDK,TKW,and FAV.When the concentration of oxygen decreasd to 8%,the damage capability of P.interpunctella was significantly inhibited.After storage for 42 d,the TKW did not change significantly,indicating that the feeding capability of P.interpunctella was significantly inhibited,but the IDK and FAV also showed remarkable changes,indicating that this concentration is still not enough to completely suppress the damage ability of P.interpunctella.