Effect of Nutritional Supplements on Some Biological and Physiological Parameters of Graphosoma lineatum L.

The striped bug, Graphosoma lineatum L. is one of the pests of Apiaceae family such as parsley, carrot, celery and some medicinally important plants. The adults and nymphs of this insect feed on seeds of host plants. The eggs of the striped bug have an important role in mass rearing program of some parasitoids. Nutritional supplements undertake an essential function in mass rearing of insects and increase the efficiency of production. Vitamins such as B group have different functions in physiology of insects. The growth and development of insects hinge on acquiring essential nutrients through food materials. Apart from their primary food source, insects rely on essential amino acids and certain minerals for proper nutrition. These crucial components must be obtained from their food sources. Symptoms of nutritional deficiency, as reported in various research studies, include delayed growth, weight loss, prolonged immature stages, increased mortality, wing deformities, alterations in mating behaviors, and various physiological issues. In this study the effects of some vitamins and amino acids on anatomy of salivary glands, total protein of body, developmental time and fecundity of G. lineatum were evaluated in controlled conditions.

Insects reared on parsley seeds adhered on the inner side of big plastic containers in controlled condition. Supplements including vitamins B12, B6, B1 and Serine and Phenylalanine amino acids selected for evaluation. These supplements used for the treatmnet of G. lineatum in four different concentrations dissolved in water. For evaluating the effects of nutritional supplements on anatomy of salivary glands, both glands separate after dissection of adult’s thorax, and dimension of glands including width and length of posterior and anterior lobs, measured by micrometer apparatus located on stereomicroscope. Total body protein measured by Kjeldahl apparatus after well drying the total body of insects in oven followed by fine powder of dry materials. Total protein was determined using a standard method, calculated by multiplying the nitrogen amounts by 6.38, a constant value. In distinct experiments, the impact of nutritional supplements on the duration of each nymphal stage was investigated. One-day-old eggs were employed for this purpose. Following treatment justification, the time required for the development of each instar was recorded on a daily basis. All tests were replicated three times, with distilled water used for the control treatment. The data were analyzed by One-way ANOVA experimental randomized design and Duncan’s multiple range test using SAS software used for comparing the means.

The results disclosed a significant impact of all vitamins and amino acids on all studied parameters. Notably, in the case of salivary glands, the posterior lobe exhibited a more pronounced effect in insects fed with B1, B6, and Phenylalanine. Different concentrations of vitamin B6, B1 and Phenylalanine affected total protein content of male and female insect’s body. Vitamin B12 had non-significant effect on male and female total body protein. Nutritional supplements changed the rate of laid and hatched eggs in addition with nymph’s developmental time. Vitamin B12 in the concentration of 0.005 g/l, B6 in the concentration of 0.25 g/l, B1 in the concentration of 0.5 g/l, Serine and Phenylalanine both in the concentration of 0.5 g/l showed the highest rate of laid and hatched eggs. Vitamin B6 and B1 in the concentration of 1 and 1.5 g/l resulted in prolonging the nymph’s life span in comparing with controls. The negative effects of high concentrations of nutritional supplements on fecundity and normal developmental period of nymphs well documented in this study. Metabolism, cell division, hormone synthesis, enzymes activity and many physiological parameters affects by supplements especially vitamins. Any disorder in utilization, absorption and inhibition of their function leads to biological and behavioral problems in insects. In some cases, the function of symbionts for compensation essential supplements documented.   

The results of this study indicate important function of vitamins B12, B6 and B1 on G. lineatum nymphal developmental period. In high concentrations, rate of growth decreased in comparison with controls. Salivary glands anatomy showed some changes in dimensions especially in posterior lobs in dose-depending manner. Number of eggs laid and hatched decreased especially in high concentrations of nutritional supplements. The results of this study will help to justify better meridic diet for rearing striped bug. In semi-artificial diets for rearing this insect, corporation of little concentrations (optimum) will improve the fitness of insects.