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1. Action of fenoxycarb on metamorphosis and cocoon spinning in Chrysoperla carnea (Neuroptera: Chrysopidae): identification of the JHA-sensitive period

Creator:
Bortolotti, Laura, Micciarelli Sbrenna, Anna, and Sbrenna, Giovanni
Type:
article, model:article, and TEXT
Subject:
Chrysoperla carnea, juvenoids, fenoxycarb, development, metamorphosis, and JH sensitive period
Language:
English
Description:
Fenoxycarb is an insecticide with a juvenile hormone mimicking effect, which disturbs metamorphosis in several insect species, including the neuropteran Chrysoperla carnea. Administration of different doses of fenoxycarb to third instar larvae causes a dose dependent inhibition of metamorphosis and cocoon spinning. When treated within 48 h of the last larval ecdysis, this insect shows a temporary inhibition of metamorphosis and cocoon spinning, which leads to a prolongation of the third larval instar. When treated after 60 h into the last instar, most of larvae were unable to metamorphose and spin a cocoon. Thus, C. carnea is most sensitive to this juvenoid in the period after 60 h into the last larval instar.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

2. Activation of gonads and disruption of imaginal diapause in the apple blossom weevil, Anthonomus pomorum (Coleoptera: Curculionidae), with juvenoids in laboratory and field trials

Creator:
Žďárek, Jan, Čtvrtečka, Richard, Hovorka, Oldřich, and Košťál, Vladimír
Type:
article, model:article, and TEXT
Subject:
ecophysiology, reproduction, diapause, aestivo-hibernation, juvenoids, Anthonomus pomorum, and Curculionidae
Language:
English
Description:
A possibility of using synthetic analogues of juvenile hormone (juvenoids) to disrupt imaginal diapause of the apple blossom weevil, Anthonomus pomorum females was demonstrated. Out of three preparations tested (methoprene, fenoxycarb and W-328) methoprene and fenoxycarb appeared to be effective. Sensitivity to juvenile hormone analogues develops early after imaginal emergence (even before the female starts to feed) and lasts throughout the whole aestivo-hibernation dormancy. Although the juvenoids could stimulate the onset of oogenesis at any time during diapause, the propensity of the ovaries to form normal eggs developed only during hibernation part of the dormancy; in earlier stages of diapause accumulation of yolk was observed but matured eggs were not produced. Methoprene treatment caused marked increase of locomotory activity accompanied with decrease of dry weight, increase of water content, depletion of trehalose resources, decrease of cold hardiness and, finally, 100% mortality within four weeks in the weevils treated during their feeding or aestivation stages. Although similar changes were observed in the treated pre-feeding weevils, they later recovered and survived until next spring without apparent loss of cold hardiness. A possibility of designing a control method based on this principle is discussed and the results of small-scale field trials that support its plausibility are reported.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public