The greater wax moth, Galleria mellonella Linnaeus, is a ubiquitous pest of the honeybee, Apis mellifera Linnaeus, and Apis cerana Fabricius. The greater wax moth larvae burrow into the edge of unsealed cells with pollen, bee brood, and honey through to the midrib of honeybee comb. Burrowing larvae leave behind masses of webs which causes galleriasis and later absconding of colonies. The damage caused by G. mellonella larvae is severe in tropical and sub-tropical regions, and is believed to be one of the contributing factors to the decline in both feral and wild honeybee populations. Previously, the pest was considered a nuisance in honeybee colonies, therefore, most studies have focused on the pest as a model for in vivo studies of toxicology and pathogenicity. It is currently widespread, especially in Africa, and the potential of transmitting honeybee viruses has raised legitimate concern, thus, there is need for more studies to find sustainable integrated management strategies. However, our knowledge of this pest is limited. This review provides an overview of the current knowledge on the biology, distribution, economic damage, and management options. In addition, we provide prospects that need consideration for better understanding and management of the pest.

The spotted wing drosophila, Drosophila suzukii Matsumura, is an insect pest of soft-skinned fruit, native to Eastern Asia. Since 2008, a world-wide dispersal of D. suzukii is seen, characterized by the establishment of the pest in many Asian, American and European countries. While the potential for invasion of continental Africa by D. suzukii has been predicted, its presence has only been shown for Morocco in Northern Africa. Knowledge about a possible establishment in other parts of the continent is needed as a basis for pest management. In 2019, we carried out a first survey in three counties in Kenya to monitor for the presence of D. suzukii using traps baited with a blend of apple cider vinegar and red wine. A total of 389 D. suzukii flies were captured in a fruit farm at Nakuru county, with more female flies being trapped than males. We confirmed the morphological identification of D. suzukii using DNA barcoding. In 2020, we performed a follow-up survey at 14 locations in six counties to delimit the distribution of D. suzukii in the main berry growing zones in Kenya. The survey indicated that so far D. suzukii is restricted to Nakuru county where it was initially detected. This is the first study to provide empirical evidence of D. suzukii in continental sub-Saharan Africa, confirming that the pest is expanding its geographic range intercontinentally. Given the high dispersal potential of D. suzukii, a concerted effort to develop management strategies is a necessity for containment of the pest.

Background Drosophila suzukii is among the main pests of berries, and to which control, primarily through application of insecticides is challenging and urges alternative strategies. Methods based on targeting chemical sensing and interfering with the behavior of this pest insect are promising, and are facilitated by the isolation and functional characterization of chemosensory receptors aimed to identify behaviorally active ligands. In our previous investigations, we functionally characterized subunits of the OR69a locus of Drosophila melanogaster as being capable to bind both pheromones and kairomones. OR69a is well conserved within the genus Drosophila, and represents a candidate target for a broad behavioral interference based on chemosensory communication towards the design of novel control strategies. Results By means of heterologous expression in empty ab3A neurons of D. melanogaster together with Single Sensillum Recording (SSR), we screened three OR69a-subunits we have identified in D. suzukii (DsuzOR69aA, DsuzOR69aB, DsuzOR69aC) with a panel of 48 ligands. We deorphanized these subunits to several compounds, including two possible kairomones (3-octanol and R-carvone) and (Z)-4-nonenal, a possible fly-emitted volatile compound, although with different pharmacological qualities. By coupling Gas Chromatography to Single Sensillum Recording (GC-SSR), we demonstrated these three ligands enhance ab3A-spiking at nanogram aliquots in a complementary fashion among the different OR69a variants, and we identified another possible kairomone, methyl salicylate, as the most active and specific ligand for the sole subunit DsuzOR69aB. In testing headspaces collected from D. suzukii female and from the fly-associated yeast Hanseniaspora uvarum by GC-SSR we did not observe activation from female headspaces but activation from headspaces collected from yeast. In situ hybridization analysis conducted on D. suzukii antennae suggested unique expression of OR69a-subunits into specific neurons as well as their possible co-expression within the same neurons. Conclusions The OR69a-subunits of D. suzukii constitute cation channels, which binding suggests kairomone specificity, even if effects may coexist for binding the possible fly-emitted volatile compound (Z)-4-nonenal in a complementary fashion. Among the possible kairomones, methyl salicylate is the most active ligand and it demonstrated to be specific to the sole DsuzOR69aB subunit, inspiring future investigation to validate potentials of this compound for D. suzukii pest control strategies.

To ensure dispersal, many parasites and pathogens behaviourally manipulate infected hosts. Other pathogens and certain insect-pollinated flowers use sexual mimicry and release deceptive mating signals. However, it is unusual for pathogens to rely on both behavioural host manipulation and sexual mimicry. Here, we show that the host-specific and behaviourally manipulating pathogenic fungus, Entomophthora muscae, generates a chemical blend of volatile sesquiterpenes and alters the level of natural host cuticular hydrocarbons in dead infected female house fly (Musca domestica) cadavers. Healthy male house flies respond to the fungal compounds and are enticed into mating with dead female cadavers. This is advantageous for the fungus as close proximity between host individuals leads to an increased probability of infection. The fungus-emitted volatiles thus represent the evolution of an extended phenotypic trait that exploit male flies' willingness to mate and benefit the fungus by altering the behavioural phenotype of uninfected healthy male host flies..