Datos preliminares sobre la biología de Paracentrobia nr acuminata (Ashmead) (Hym.: Trichogrammatidae) parasitoide de huevos de la chicharrita Tapajosa rubromarginata (Hem.: Cicadellidae) in Argentina

VIRLA, EDUARDO; LUFT ALBARRACIN, ERICA; LOGARZO, GUILLERMO; TRIAPITSYN, SERGUEI

San Miguel de Tucumán-Tucumán.

Congreso; VI Congreso Entomológico Argentino.; 2005

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> The glassy winged sharpshooter, Homalodisca coagulata (Hem.: Cicadellidae) is a very serious problem pest in grapes vines, in California (USA). In order to identify candidates for biological control of this pest, a survey of egg parasitoids was started Argentina in 2000. Most of the collection was carried out in northwestern Argentina using “sentinel eggs” of Tapajosa rubromarginata, a sharpshooter related to H. coagulata. T. rubromarginata is common in different crops of Tucumán. As a result of the survey wasps of 14 different species in 5 genera were obtained: eight species of Gonatocerus and one of Polynema (Mymaridae), one species of Paracentrobia, 2 species of Oligosita and 2 of Zagella (Trichogrammatidae). This study reports the field and laboratory results of P. nr acuminata. Field studies included a seasonal sampling of egg masses in two localities of Tucumán Province to estimate parasitoid incidence and occurrence. Studies on duration of development, sex ratio, adult longevity, and parasitic rates were carried out in the laboratory. From the samples taken on the wild vegetation parcel, in San Miguel de Tucumán, a total 5148 host eggs were sampled, and 2044 eggs (39.7%) were attacked by the egg parasitoids complex composed for Trichogrammatidae and Mymaridae P. nr acuminata represent the 3.9% of all the emerged wasps. P. nr acuminata occurred from August to March. From the samples taken at El Manantial a total 563 host eggs were sampled, and P. nr acuminata represent the 2.4% of all the emerged wasps. Field sex ratio was female biased. Multiparasitism with three species of thichogrammatid was recorded. In laboratory P. nr acuminata is a primary parasitoid. Under low density of females this parasitoid produced only one adult per host egg. However when females’ pressure was increased there is possible to observe 2, 3 or 4 individuals per host egg (not detected in field offspring). In laboratory, 395 eggs were exposed, 68.7% were parasitized and only 46 sharpshooter nymph emerged (11.65 %). The duration of development (from oviposition to adult emergence) of P. nr acuminata averaged 21.27 ± 2.33 days and the overall sex ratio was 1: 1. The wasp reproduces sexual and parthenogenetically (arrhenotokus) so, if only sexual reproduction is considered, sex ratio is female biased.  Average of adult longevity was 6.75 ± 4.47 days and females lived longer than males. The discussion included comments regarding the possibility to use this egg parasitoid as a biological control agent.