Effects of host plants nutrient on the nutrient in Bradysia cellarum and Bradysia impatiens

Abstract

25The chive maggots Bradysia cellarum the fungus gnats Bradysia impatiens are two main 26 root pests of plants. They can coexist on same host plants and have become devastating pests on 27 liliaceous crops and edible fungi. Their growth and development are affected by nutrients of their 28 host plants. We studied the effects of different host plant nutrients on the nutrient contents of these 29 two Bradysia species. We assayed the nutrients in the roots of chive, board bean (B-bean), lettuce, 30 cabbage, wild cabbage (W-cabbage) and pepper, and analysed the nutrient content of the two 31 Bradysia species after three continuous generations of feeding on these different host plants. There 32 chive and B-bean had higher contents of protein, free amino acid and starch than in other host 33 plants. Soluble sugar, fat and protein contents were significantly higher in both Bradysia species 34 when they were reared on chive and B-bean than when reared on cabbage, lettuce, W-cabbage and 35 pepper. Our study provides a reference for further studies on the host range of the two Bradysia 36 species, as well as knowledge for consideration in field crop rotations. 37 38 Keywords: Bradysia cellarum, Bradysia impatiens, host plant nutrient, insect nutrient 39 40 42 Zhang, 1985) and the fungus gnats Bradysia impatiens Johnnsen, 1912 (= Bradysia difformis Frey, 43 1948), are two main root insect pests which belong to the family Diptera and the genus Sciaridae 44 [1, 2]. They may coexist on the same host plants and have become devastating pests on liliaceous 45 crops and edible fungi [3]. The larvae of these species attack their host plants by chewing or 3 46 stripping plant roots, especially the young and developing root hairs and stems of seedlings, and 47 leading to losses in crop production and hindering agricultural productivity as well as farmers' 48 income [2, 4]. In outdoor fields, the two Bradysia species occur with similar regularities and 49 outbreak in spring and autumn, while populations decline in summer [4]. The chive maggots B. 50 cellarum heavily attacks chive, onion, garlic, cabbage and watermelon seedlings [5-8]. The fungus 51 gnats B. impatiens [9] also causes damages to chive, lily, green onion, garlic, B-bean, cabbage, 52 butterfly orchid and jonquil [10-13], which was first recorded on the edible mushroom in Yunnan, 53 China in 2009 [14, 15]. 54 Successful growth, development, and reproduction of plant-feeding insects depend on 55 finding suitable host plants and obtaining adequate nutrition from them. It was found that there 56 were significant differences among different host plants for the developmental duration, life57 longevity and population trend index of the fruit fly (Bactrocera), indicating that the fly's 58 population was influenced by host plant nutrition [16]. Protein, amino acid, soluble sugar and 59 starch are the main nutrients in plants, which have a great influence on the growth, reproduction, 60 survival rate and spawning of herbivores [17]. For example, higher soluble sugar content in whe...