Effect of Nitrogen Fertilizer on Biological Parameters of the Aphis craccivora (Hemiptera: Aphidiae) and Associated Productivity Losses in Common Globe Amaranth

Reducing nitrogen status of floriculture plants is an effective tactic in pest management by decreasing host plant quality. Life table parameters and population growth rate of Aphis craccivora(Hemiptera: Aphidiae), as well as cosmetic and qualitative parameters losses associated with aphid infestation were evaluated in relation to N fertilization levels on Gomphrena globosa, under greenhouse condition. Four N fertilization levels (0, 30, 60, and 100% of recommended 2 kg m-3) were used. The results indicated that aphid’s intrinsic rate of natural increase on plants fertilized with 100% of the recommended N level was the highest. Abundance and population growth rate of aphid also positively correlated with N fertilization levels. The interactive effect of aphid population and N fertility significantly affected growth parameters of the plants. In the absence of aphid, plant yield improved linearly with increasing N levels. However, aphid population highly decreased shoot to root ratio and the number of flowers in plants fertilized with 100% of the recommended N level. According to our findings, fine-tuning fertility to reduce A. craccivora population is a steadfast tactic to produce marketable globe amaranth ornamental plant.