Desenvolvimento de imaturos de Dilobopterus costalimai Young, Oncometopia facialis (Signoret) e Homalodisca ignorata Melichar (Hemiptera: Cicadellidae) em citros

Abstract

Development of Immature Stages of Dilobopterus costalimai Young, Oncometopia facialis (Signoret) and Homalodisca ignorata Melichar (Hemiptera: Cicadellidae) on Citrus ABSTRACT-The development of immature stages on citrus seedlings was studied for the sharpshooter leafhoppers Dilobopterus costalimai Young, Oncometopia facialis (Signoret) and Homalodisca ignorata Melichar. The former two species are vectors of Xylella fastidiosa to citrus. Eggs of the three species are laid underneath the epidermis in the abaxial leaf surface. The Proconiini species (O. facialis and H. ignorata) coat their eggs with a whitish powder. Mean egg incubation periods at 25±2 0 C were 11.8 and 9.5 days for D. costalimai and O. facialis, respectively. Nymphal development was observed under fluctuating temperatures in a greenhouse after confining newly hatched first-instar leafhoppers on seedling stems inside leaf cages (54x42x12 mm). Five instars were observed and the mean durations of the nymphal stage were 64.7, 76.2 and 53.1 days for D. costalimai, O. facialis and H. ignorata, respectively.

Alternation of host plants as a survival mechanism of leafhoppers Dilobopterus costalimai and Oncometopia facialis (Hemiptera: Cicadellidae), vectors of the Citrus Variegated Chlorosis (CVC)

“…These data are in accordance with those found by Almeida & Lopes (1999), who observed a high mortality of nymphs of D. costalimai and O. facialis reared on citrus cuttings.…”

“…Thus, Lopes et al (1998) cited D. costalimai and O. facialis as species occurring in citrus and coffee areas and they suspected that they were a common vector of bacterium Xylella fastidiosa for both crops. Almeida & Lopes (1999) verified that the mortality of the nymphal stage of species D. costalimai and O. facialis reared on the upper third part of citrus seedlings (sprouts) was 80.5 and 75.4%, respectively, and over 66% of the mortality occurred on the first instar. Yamamoto & Gravena (2000), while studying the populational abundance of citrus leafhoppers classified the species D. costalimai and O. facialis as accidentally occurring in citrus groves.…”

Espécies de cigarrinhas (Hemiptera, Cicadellidae, Cicadellinae) em pomares de citros da região de Bebedouro, SP, com descrição de uma espécie nova de Acrogonia Stål

“…Predominantemente, a sua postura localiza-se na face inferior da folha, em grupos de 4 a 21 ovos dispostos, lado a lado, em uma fileira levemente arqueada e cobertos por uma fina camada de epiderme. A fase jovem dura, em média, 76 dias, sob temperatura flutuante (ALMEIDA & LOPES 1999 Diagnose. Coloração geral muito variável, do verde até um verde-violáceo, podendo apresentar, ou não, conspícuas manchas escuras na coroa.…”

“…A eclosão da ninfa dá-se por uma das extremidades do ovo, caracterizada pelo opérculo. Passa por cinco ínstares antes de atingir a fase adulta, com duração média de 65 dias à temperatura flutuante (ALMEIDA & LOPES 1999). (Signoret, 1854) (10A-10F)…”

Identification of a non-host plant of Xylella fastidiosa to rear healthy sharpshooter vectors

“…Protocols to rear sharpshooters for multiple generations in the laboratory have not been developed and a good strategy to obtain healthy insects for transmission experiments would be to select a host plant that supports nymphal development, but not the multiplication of X. fastidiosa. Vernonia condensata Baker (Asteraceae) and Aloysia virgata (Ruiz & Pavan) Juss (Verbenaceae) were found to frequently harbor large numbers of leafhopper sharpshooters and other xylem feeding insects (Almeida, 1999;Giustolin et al, 2002), including species identified as X. fastidiosa vectors to citrus (Roberto et al, 1996;Krügner et al, 2000). Previous work has shown that V. condensata ('boldo' or 'alumã') supported the development of sharpshooter nymphs (Almeida, 1999;Milanez et al, 2001).…”