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Entomophaga

, Volume 37, Issue 1, pp 79–89 | Cite as

Biology and host specificity ofOncochila simplex [Hem.: Tingidae], a candidate for the biological control of leafy spurgeEuphorbia esula L. “complex”

  • P. Pecora
  • A. Rizza
  • M. Stazi
Article

Abstract

Bionomical and host-range studies of the lacebug,Oncochila simplex (Herrich-Shaeffer) (Hemiptera: Tingidae), a candidate for the biological control of leafy spurge (Euphorbia esula L. “complex”) in the United States, were made during the years 1979 to 1982 at the USDA-ARS Rome Laboratory, and during 1981 and 1982 at the USDA-ARS Albany, California laboratory. A total of 26 test plant species, varieties, or population was used.

Oncochila simplex overwinters as adults and nymphs at the base of its host, 4 to 5 cm below the soil surface. In the Piacenza area (northern Italy) adults first appeared at the end of March and were present as 5 successive generations until the end of September. In the laboratory, under long day (L: D-16: 8) conditions, reproduction was continuous, amounting to 11 generations during 1981. Each life cycle was completed in 33 to 40 days. The ♀♀ laid eggs under the mesophyll of stems. An average of 175±10.93 eggs per female were produced. Of a sample of 1,580 eggs, 83% were fertile.Oncochila simplex has 4 nymphal instars. Adults lived 50–70 days.

In no-choice tests, neonate nymphs ofO. simplex developed on plants of the genusEuphorbia (subgenusEsula) and on lettuce and corn. In field trials, this lacebug completed a generation onEuphorbia lathyris L., but not on lettuce and corn. The development of neonate nymphs under forced conditions on lettuce and corn does not necessarily indicate that these plants are suitable hosts in nature. Our hypothesis of the restricted host range ofO. simplex is also supported by the literature, in which there are no reports of this species from lettuce, corn or other plants of agricultural importance. We conclude thatO. simplex should be introduced as a biological control agent against leafy spurge in the United States.

Key Words

weeds herbivore phytophagous 

Résumé

Des études bionomiques et trophiques d'Oncochila simplex (Herrich-Shaeffer) (Hem.: Tingidae), agent potentiel de lutte contreEuphorbia esula L. «complex» aux Etats-Unis ont été réalisées au cours des années 1979–1982 au laboratoire USDA/ARS, à Rome et pendant les années 1981–1982 au laboratoire USDA/ARS, Albany (Californie).

Les adultes et les nymphes d'Oncochila simplex hivernent à la base de leurs plantes hôtes, à 4–5 cm au-dessous du sol. Dans la région de Piacenza (Italie du Nord), les adultes réapparaissent à la fin mars et sont présents pendant 5 générations successives jusqu'à la fin de septembre. Au laboratoire, sous des conditions de jour long (16L∶8D), la reproduction a été continue, atteignant 11 générations en 1981. Le cycle de développement dure de 33 à 40 jours. Les femelles insèrent leurs œufs au-dessous du mésophylle des tiges. Une moyenne de 175±109 œufs/femelle a été enregistrée. Sur un échantillon de 1 580 œufs, 83% ont été fertiles.Oncochila simplex a 4 stades larvaires et les adultes peuvent vivre de 50 à 70 jours.

Dans les essais sans choix, les larves néonates d'O. simplex ont présenté un développement sur les plantes du genreEuphorbia (sous-genreEsula) et sur salades et maïs. Dans les essais à l'extérieur, une génération s'est développée surEuphorbia lathyris, mais aucune sur salades et maïs. Le développement des larves néonates sur salade et maïs en conditions artificielles n'implique pas que ces plantes puissent constituer des hôtes possibles à l'extérieur. Notre hypothèse selon laquelleO. simplex a un spectre trophique limité a été confortée par les données de la littérature; aucune mention de cette espèce n'a été faite sur salade ou sur maïs. Nous concluons queO. simplex devrait être proposé comme agent de lutte biologique contreE. esula aux Etats-Unis.

Mots Clés

mauvaises herbes phytophage lutte biologique 

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Copyright information

© Lavoisier Abonnements 1992

Authors and Affiliations

  • P. Pecora
    • 1
  • A. Rizza
    • 1
  • M. Stazi
    • 1
  1. 1.Biological Control of Weeds Laboratory-EuropeARS-USDARomeItaly

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