Parasitoides do bicudo Anthonomus grandis e predadores residentes em algodoeiro pulverizado com caulim

Abstract

ResumoO uso simultâneo de diferentes métodos de controle é fundamental para o sucesso no manejo de pragas. Esse estudo investigou o efeito de aplicações do caulim nas populações de predadores residentes no dossel do algodoeiro e no parasitismo do bicudo em estruturas coletadas do solo em campo e, em botões florais em laboratório. A abundância de predadores residentes no dossel das plantas incluindo Araneae, Formicidae, Chrysopidae e Coccinellidae foi similar entre as áreas tratadas e não tratadas com o caulim, bem como a emergência dos parasitoides Bracon vulgaris Ashmead (Hymenoptera: Braconidae) e Catolaccus grandis Burks (Hymenoptera: Pteromalidae) oriundos de estruturas coletadas no solo em ambas as áreas. Da mesma forma, o parasitismo do bicudo em botões tratados e não tratados com caulim foi semelhante quando foram oferecidos ao parasitoide B. vulgaris em testes com chance de escolha. Sendo assim, os resultados mostram que aplicações do caulim não afetam o controle biológico natural por parasitoides associados ao bicudo e lagarta rosada e predadores residentes no algodoeiro. Palavras-chave: Controle físico, controle biológico, Anthonomus grandis e Pectinophora gossypiella AbstractSimultaneous use of control methods is essential to reach success in managing arthropod pests. The current study investigated the effect of kaolin application on resident predators in the cotton plant canopy and parasitism of boll weevil on abscised squares in the field, and parasitism of boll weevil in the laboratory. Predators Araneae, Formicidae, Chrysopidae, and Coccinellidae showed similar seasonal densities for kaolin-treated and untreated cotton fields as well as the emergence rate of the parasitoids Bracon vulgaris Ashmead (Hymenoptera: Braconidae) and Catolaccus grandis Burks (Hymenoptera: Pteromalidae) from abscised field-collected structures. Under laboratory conditions, the parasitism of boll weevil larvae infesting squares was similar when treated and untreated squares with kaolin were offered to the parasitoid under free choice test. Therefore, the results show that spraying cotton fields with kaolin does not affect the natural biological control by parasitoids of boll weevil and pink bollworm and resident predators naturally occurring in cotton fields.

Rational Practices to Manage Boll Weevils Colonization and Population Growth on Family Farms in the Semiárido Region of Brazil

“…Boll weevil attack rates were lower in experimental fields treated with kaolin [ 14 ]. Encouragingly, the same rates of parasitism on caged studies by Bracon vulgaris Ashmead, the major boll weevil parasitoid in our areas, and field parasitism rates of this parasitoid and Catolaccus grandis Burks were reported under kaolin treatments [ 10 ].…”

“…Boll weevil immature stages exhibit low natural mortality from natural enemies [ 9 , 10 ] and are difficult to control with insecticides, because they are partially protected inside cotton fruit bodies. Current insecticide-based practices require 5–6× sequential sprays at ~5-day intervals, with the intent of killing adults emerging from fallen fruiting bodies before they are able to oviposit [ 11 ].…”

Behavioral Studies of the Parasitoid Bracon vulgaris Ashmead (Hymenoptera: Braconidae)

“…Altogether, 13 species of boll weevil parasitoids have been described (Araújo et al 2000;Ramalho and Wanderley 1996;Santos et al 2013). Among these, Bracon vulgaris (Ashmead) and Catolaccus grandis (Burks) are the main biological agents responsible for reducing natural populations of boll weevil in the Northeast of Brazil (Ramalho et al 2007;Silva-Torres et al 2009b;Santos et al 2013). Carvalho et al (2000) found that B. vulgaris can achieve high rates of parasitism of A. grandis (≅ 70 %), especially at the end of the cropping season.…”

Spatial and temporal distribution of cotton squares and small cotton bolls fallen on ground after damage by boll weevil and the efficiency of the equipment used to collect them

“…Despite functioning well, this collector was little used by small cotton producers, perhaps because the practice of collecting and destroying cotton squares fallen on the soil was little known by cotton farmers and/or was characterized as a hard work, dependent on hand labor, and questionable regarding their viability depending on the size of the field area (SANTOS et al, 2013). Therefore, the accumulation of data on the improvement of this farming practice may be of great importance for small cotton farmers.…”