Growth Regulators IGRs

Thompson HM, Wilkins S, Battersby AH, Waite RJ, Wilkinson D. 2005. The effects of four insect growth-regulating (igr) insecticides on honeybee (Apis mellifera L.) colony development, queen rearing and drone sperm production. Ecotoxicology 14 757-769. 

In addition to pheromones (vide infra), we were interested in juvenile hormones (JHs), and synthesized ( )-juvabione [12] and (-t-)-juvabione [13-14]. JH mimics were later found to be useful as practical insect growth regulators (IGRs). We synthesized ( )-JH I [15], (-i-)-JH I [16] and unnatural (-)-JH I [17]. The naturally occurring (-i-)-JH I was 1.2 x lO times more active than (-)-JH I. Chirality plays an important role at JH receptor sites. 

The first test of an insect growth regulator (IGR) on a non-Apis bee was presented during a symposium in 1993 [25], The authors observed adult mortality and brood development in bumble bee colonies B. ter-restris) maintained in cages. Forage plants were treated during activity hours with the IGR fenoxycarb. It was concluded that the IGR did not present a negative action on adult bumble bees but that a larval test had to be developed for an adequate assessment of the brood mortality. 

Insect growth regulators (IGR). IGR s are chemicals that are able to act on the endocrine and hormone systems of insects. Highly specific in their action, they have received much attention as potential insecticides for wood protection. Many of the newer IGR s mimic the juvenile hormone and effectively inform the insect to remain in the immature state. Adult insects treated with such products are also unable to moult... 

The multiresistant strains now extant also show a certain cross-tolerance, but not resistance, to the third-generation insecticides such as the juvenile-hormone mimics and other so-called insect growth regulators, as was found in strains of the housefly, flour beetle and tobacco budworm. Resistance to the JH mimic methoprene and Monsanto-585 has been induced by laboratory selection of Culex taxsalis (28) and Culex pipiens (29), and to Monsanto-585 in Culex quinquefasstatus (30). Whatever insect or IGR is chosen, the result of exposure to selective doses in successive generations is usually the development of resistance, repeating our previous experience with chemosterilants, and the... 

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