Interaction of Rotylenchulus reniformis and Meloidogyne javanica with mealybug wilt of pineapple, in microplots Thiago de Freitas Ferreira & Ricardo Moreira Souza & Karla Daiana dos Santos Ferreira & Welington Sérgio Silva Idalino Accepted: 11 December 2014 # Koninklijke Nederlandse Planteziektenkundige Vereniging 2014 Abstract Mealybug wilt of pineapple (MWP) is a dis- ease complex whose etiology seems to involve the mealybug Dysmicoccus brevipes and pineapple mealy- bug wilt-associated virus-1, -2 and/or -3. MWP, the reniform and the root-knot nematodes (RN, RKN) are major problems of pineapple crop worldwide. Although these nematodes are often found in MWP-affected plan- tations, so far, no study has investigated possible inter- actions among these pests causing symptoms and affect- ing the development of pineapple plants. Pineapple plantlets free of diseases and pests (Vitória cultivar) were inoculated with i) RN; ii) RKN; iii) viruliferous mealybugs; iv) RN and viruliferous mealybugs; and v) RKN and viruliferous mealybugs. Uninoculated plants served as controls. After inoculation, the plants were transplanted into microplots, where shoot symptoms and growth were assessed at 9 and 16 months after inoculation. RN, RKN and MWP induced distinct shoot symptoms, which appeared much worse in co- inoculated plants, including the collapse and death of nearly half of the experimental plants at 16 months. RKN, RN and MWP, alone or in combination, reduced the fresh weight of the root system up to 88 % and shoot weight up to 68 %. The interaction among these pests was additive. The results of this experiment emphasize the need for further studies conducted in commercial plantations to understand the interactions among RKN, RN and MWP, and their relative importance, since these are often misdiagnosed and consequently poorly managed. Keywords Reniform nematode . Root-knot nematode . Dysmicoccus brevipes . Pineapple mealybug wilt- associated virus . Ananas comosus Introduction In Brazil, pineapples (Ananas comosus L. Merril) are cultivated in several states, especially by smallholders. In recent years the pineapple agribusiness has expanded considerably, becoming the economic mainstay of many regions and families (IBGE, 2010). The pineapple plant is affected by a wide variety of pests and diseases, with plant parasitic nematodes (PPNs) and mealybug wilt of pineapple (MWP) being the main problems (Lacerda et al. 2009; Rohrbach and Apto 1986; Sipes et al. 2005). Surveys in the main production areas of Brazil have indicated that Meloidogyne javanica (Treub, 1885) Chitwood, 1949 and Rotylenchulus reniformis Linford and Oliveira 1940 are among the most frequent and damaging PPNs (Cavalcante et al. 1984; Costa et al. 1998; Manso et al. 1994; Zem and Reinhardt 1978). Yield losses due to R. reniformis vary from 60 to 74 % in the first harvest and around 40 % in the second (“ratton”) harvest, which is obtained from plantlets that develop between the Eur J Plant Pathol DOI 10.1007/s10658-014-0576-5 T. d. F. Ferreira : R. M. Souza (*) : K. D. d. S. Ferreira : W. S. S. Idalino Grupo de Pesquisa em Nematologia, Universidade Estadual do Norte Fluminense Darcy Ribeiro/CCTA/LEF, Campos dos Goytacazes, RJ, Brazil e-mail: ricmsouza@censanet.com.br