Paternal allocation of sequestered plant pyrrolizidine alkaloid to eggs in the danaine butterfly, Danaus gilippus

Pyrrolizidine alkaloid sequestered by adult male Danaus gilippus from plants is transferred in large measure to the female at mating, and by the female to the eggs. The eggs, presumably, are protected as a result. The male's courtship pheromone, danaidone, derived from the sequestered alkaloid, may function to advertise the male's alkaloid-donating capacity.     

Experimental evidence of the territorial defense,hypothesis in insular Blue Tits

Many insular vertebrates have unusually high population densities and are characterized by behavioural shifts including reduced territory size and reduced situation-specific aggressiveness. Compared to their mainland counterparts, Blue Tits on the island of Corsica exhibit many traits that fit the trends observed in crowded insular populations. We demonstrate from behavioural observations in aviaries and from hormone measurements that Corsican its are less aggressive than mainland ones. These shifts, as well as changes in reproductive patterns, support the defense hypothesis.     

Hormonal control of pheromone responsiveness in the male black cutwormAgrotis ipsilon

In Lepidoptera, reproduction is linked to chemical communication between conspecific partners. When exposed to the female sex pheromone, males respond by exhibiting typical sexual behaviour which leads to mating. Here we show that presence of the juvenile hormone producing gland (corpora allata) of the male black cutworm,Agrotis ipsilon, is necessary for pheromone responsiveness. Allatectomized males do not show any sexual behaviour, although their antennal olfactory system is functional. Allatectomized males implanted with active corpora allata recover full pheromone receptivity. It is suggested that reproductive processes are synchronized in males and females through endocrine control; timing of the mating activity could serve as an adaptive strategy linked to the migratory behaviour of this species.     

Identification of an oviposition-regulating pheromone in the European grapevine moth,Lobesia botrana (Lepidoptera: Tortricidae)

The oviposition of the European grapevine moth (EGVM)Lobesia botrana can be deterred by an extract of conspecific eggs corresponding to 20 egg equivalents. The reduction of the oviposition behavior is dose-dependent. Nine chemicals have been extracted from the eggs and identified as straight chain fatty acids and esters of fatty acids. A mixture of these rather simple molecules induces the same levels of deterrence as the total extract. It might be possible to use oviposition regulating pheromone in the future for the control of EGVM populations.     

Extra-nuclear inheritance in a sexually produced aphid: the ability to overcome host plant resistance by biotype hybrids of the greenbug,Schizaphis graminum

Summary Greenbugs of biotype E that grow and reproduce well on a biotype C-resistant sorghum (IS 809) were crossed with biotype C greenbugs. The resulting hybrids were tested on IS 809 to study how the ability to overcome the cultivar's resistance is inherited. Only those hybrids stemming from biotype E mothers were able to overcome the resistance of IS 809 plants, indicating that this trait is inherited by the sexually-produced fundatrices in an extra-nuclear manner from the mother. A plausible explanation for this phenomenon is presented.