Effects Of Induced Resistance In Wild Soybean On Oviposition Preference,Developmental Performance And Food Utilization In Spodoptera Litura

Induced plant resistance has the advantages of environmental protection and ecological safety,and it plays an important role in prevention and control of crop diseases and insect pests.Currently,some plant resistance inducer like Salicylas and Methyl jasmonate,have been found to impact insect growth and reduce the damage to plants.Spodoptera litura is an important pest on crucifereae.Some studies have been made on induced resistance effect in cultivars to S.litura,but little attention has been given to induced resistance in wild soybean plants resistance.In this thesis research program following experiments were carried out on:(1)effects on the oviposition preference and larval developmental performances of S.litura feeding on wild soybean that were damanged by S.exigua feeding;(2)effects of on food utilization of S.litura feeding on wild soybean that were damanged by S.exigua feeding.Main results and conclusions obtained in the experiments are reported here.1.Effects of herbivore-feeding wild soybean plants on oviposition preference and developmental performance of Spodoptera lituraSpodoptera litura female adults were provided with a potted intact soybean seedling(control)and one which was previously damaged by S.exigua larvae feeding to oviposit.S.litura moth showed a strong favor for the control plant over the damage-treated one,ovipositing on the former by 19 out of 20 trials.Developmental parameters of larvae feeding on the two plants were measured in body weight after 9,12,and 15 days post feeding.The results showed that the larva feeding on the damage-treated plant leaves on day-9,day 12,and day-15 decreased in body weight by 56.00%,36.50%,and 39.14%compared to the control,respectively.The results suggest that herbivore-feeding induced wild soybean plants may have a repellent impact on S.litura adults to oviposit and adverse effects on larval developmental performances.2.Effects of herbivore-damaged wild soybean plants on food utilization of Spodoptera litura larvaeSpodoptera exigua 3rd instar larvae were fed with either the control soybean plants or the plants that had been damaged by S.exigua feeding,and measured in food consumption and utilization efficiency indices.The feeding-damage treated soybean plant did not influence the body weight gain,consumption,approximate digestibility,efficiency of conversion of digested food and efficiency of conversion of ingested food,but reduced the relative consumption rate and relative growth rate.The results suggest that wild soybean plants can be induced by herbivore-feeding damages to perform resistance to following herbivores.