The economic threshold of infestation for the cotton bollworms on yield in Egypt

Abstract

A field experiment was conducted, based on the premise that only when a determined economic damage threshold of the cotton bollworm is reached the application of selected chemical insecticides is justified. The results obtained indicated that the economic threshold of damage for the pink bollworm (Pectinophora gossypiella) was either 17 larvae or 11% infestation/100 green bolls. For the spiny bollworm (Earias insulana) that level was 10 larvae and 8% infestation/100 green bolls (depending on the two years 1972 and 1973 averages). Zusammenfassung Zar wirtschaftlichen Schadensschwelle von 2 an Baumwolle schädlichen Lepidopteren‐Arten In Freilanduntersuchungen sollte die Frage geklärt werden, bei welchem Befall durch Pectinophora gossypiella und Earias insulana jene Schadensschwelle erreicht wird, die den Einsatz chemischer Bekämpfungsmaßnahmen rechtfertigt. Die Ergebnisse aus den Jahren 1972 und 1973 zeigen, daß bei P. gossypiella 17 Raupen oder 11% Befall auf 100 grüne Baumwollkapseln sowie bei E. insulana 10 Raupen oder 8% Befall auf 100 grüne Kapseln jeweils das Erreichen der wirtschafllichen Schadensschwelle bedeuten.

Yield, development, and quality response of dual‐toxin Bt cotton to Helicoverpa spp. infestations in Australia

“…It was difficult to establish surviving larvae on Bollgard II ® crops, hence it was not possible to rigorously assess the impact of this situation on yield. It may be possible to develop a threshold for pest treatment based on the percentage of damaged fruit (El‐Shaarawy et al., ; Simwat & Dhawan, ). Furthermore, information on crop damage could be used to artificially damage crops at intensities similar to that found in affected commercial fields, to simulate the presence of different densities and durations of larvae, and thereby examine the impact on performance of cotton.…”

An Experimental Study of Certain Neonicotinoid Insecticides on the Incidence of Early Infestation of the Spiny and the American Bollworms, Growth and Lint Yield Characteristics of Cotton Plants

“…Spiny bollworm (SBW) Earias insulana (Boisd.) and the American bollworm(ABW) Helicoverpa armigera (Hüb) are two species of noctuid moths and consider the most destructive cotton insect pests in Egypt and middle eastern countries such as Syria, Turkey and Israel ( Abo El-Nasr and Mabrouk 1973;El-Shaarawy et al 1975;Stam and Elmosa 1990). SBW is primarily a mid-and late season insect-pest of cotton; it has no diapauses and has only restricted host range when compared with H. armigera which has a wide range of alternative host plants.…”

COMPARATIVE EFFICACY OF Trichogramma evanescens WEST. AND THE BIOCIDE (AGERIN) WITH RECOMMENDED INSECTICIDES PROGRAM FOR CONTROLLING COTTON BOLLWORMS AND ITS EFFECT ON COTTON PRODUCTIVITY IN MIDDLE EGYPT REGION.

“…).These insects are the principal pest of cotton in Egypt which cause considerable loss in quality and quantity of cotton yield in spite of the wide spread use of insecticides to control of them. ( El -Shaarawy et al 1975 ;Abul -Nasr et al 1979, andMesbah et al 2003) .Pink and Spiny bollworms cause damage by attacking terminal shoots, flower buds, and green bolls. The most serious damage to cotton is caused when larvae bore into the bolls, destroying the fiber, consuming seeds, and producing putrefaction due to the accumulation of feces and fungus.…”