Comportamento de Ddiaphorina citri Kuwayama, 1908 (Hemiptera: Liviidae) em plantas de citros submetidas ao estresse salino

Abstract

The national citrus production has as one of its main obstacles the appearance of numerous pests and diseases. Among these diseases, Huanglongbing (HLB), which has the diaphorina citri Kuwayama (Hemiptera: Liviidae) as the vector, is one of the most threatening. Since the psilídeo feeds on the shoots and the flow of shoots is regulated by the availability of water to the plants, the manipulation of abiotic factors can alter the attractiveness of the plant to the insect. The physiological processes involved in the response to abiotic stress can alter the behavior of the insect vector, and, with this knowledge, allow pest management. The objective of this work was to evaluate the effects of abiotic stress (salinity) on the behavior of D. citri. The experiments were conducted at Embrapa Mandioca and Fruticultura under weed conditions. Contractile levels of salinity in insect behavior were evaluated in studies with the 'Cravo' lemon tree (Citrus limonia Osbeck). The insects came from the field and when necessary were collected nymphs taken to the laboratory until the emergence of adults. Three experiments were carried out: (a) evaluation of the behavioral response of the insect to contrasting levels of salinity (1.7 dS m-1 and 10 dS m-1). The plants were transplanted to plastic cups whose substrate was sand washed and sterilized, kept in trays with solution fertilizer control, and after 5 days were submitted to the treatments. The experimental design was randomized blocks with 5 replicates; (b) experiment of oviposition of the insect on contrasting levels of salinity. The experimental design was completely randomized, with 10 plants in each treatment and experiment (c) olfactometry evaluation, with 6 plants of each treatment and 40 insects. Physiological variables of the plant were determined during the experiment. The data were submitted to analysis of variance and the means were compared by the Tukey test (p ≤ 0.05), t test (p ≤ 0.05) or Wilxon test (p ≤ 0.05). The results showed that the nonstressed plants (1,7 dS m-1) were more attractive to the insects in terms of feeding, shelter and oviposition; for the responses to volatiles, no differences were observed between treatments.