Seasonal Abundance and Oviposition Preference of the Alfalfa Weevil Hypera postica on Vicia sativa subsp. nigra

The alfalfa weevil Hypera postica (Gyllenhal) is the most serious invasive pest of Chinese milk vetch, Astragalus sinicus L. H. postica also feeds on the leguminous plant Vicia sativa subsp. nigra (L.), an important host as a source of H. postica infections. We investigated the seasonal abundance and oviposition preference of H. postica on V. sativa subsp. nigra in Hisayama town, Fukuoka Prefecture, Japan. H. postica eggs were observed on V. sativa subsp. nigra throughout the study from January 11 to May 11, 2011 and the peak density of H. postica larvae was observed in April 11. Rapid growth of V. sativa subsp. Nigra from March 27 to April 11 corresponded with the increasing population density of H. postica larvae. The numbers of H. postica eggs positively correlated with the diameter of V. sativa subsp. nigra stems in the results of January 11 to April 11. We investigated the oviposition preference using field samples. To investigate oviposition preference behavior, an additional study should be performed in the laboratory

Diversification, selective sweep, and body size in the invasive Palearctic alfalfa weevil infected with Wolbachia

International audienceThe alfalfa weevil Hypera postica , native to the Western Palearctic, is an invasive legume pest with two divergent mitochondrial clades in its invading regions, the Western clade and the Eastern/Egyptian clade. However, knowledge regarding the native populations is limited. The Western clade is infected with the endosymbiotic bacteria Wolbachia that cause cytoplasmic incompatibility in host weevils. Our aim was to elucidate the spatial genetic structure of this insect and the effect of Wolbachia on its population diversity. We analyzed two mitochondrial and two nuclear genes of the weevil from its native ranges. The Western clade was distributed in western/central Europe, whereas the Eastern/Egyptian clade was distributed from the Mediterranean basin to central Asia. Intermediate mitotypes were found from the Balkans to central Asia. Most Western clade individuals in western Europe were infected with an identical Wolbachia strain. Mitochondrial genetic diversity of the infected individuals was minimal. The infected clades demonstrated a higher nonsynonymous/synonymous substitution rate ratio than the uninfected clades, suggesting a higher fixation of nonsynonymous mutations due to a selective sweep by Wolbachia . Trans-Mediterranean and within-European dispersal routes were supported. We suggest that the ancestral populations diversified by geographic isolation due to glaciations and that the diversity was reduced in the west by a recent Wolbachia -driven sweep(s). The intermediate clade exhibited a body size and host plant that differed from the other clades. Pros and cons of the possible use of infected-clade males to control uninfected populations are discussed

Bottom–up Effects of Crop Seeding Methods on Densities of the Alfalfa Weevil Hypera postica and Its Introduced Parasitoid Bathyplectes anurus

The alfalfa weevil Hypera postica (Gyllenhal) is the most destructive pest of leguminous crops such as alfalfa, Chinese milk vetch, and hairy vetch throughout the world, including Japan. To control H. postica, the solitary endoparasitoid Bathyplectes anurus (Thomson) was released in Japan as a classical biological control agent. In our study, we investigated the bottom-up effects of hairy vetch seeding methods (i.e., control of seeding timing and density) on the B. anurus density to develop a field production method for B. anurus. The average densities of H. postica and B. anurus were significantly higher with early timing and a higher seeding density compared with early timing and a lower seeding density, late timing and a higher seeding density and late timing, and a lower seeding density. This confirmed that the densities of H. postica and B. anurus could be adjusted by the bottom-up effect of hairy vetch seeding methods. During the tri-trophic interaction among hairy vetch, H. postica, and B. anurus, the interaction between the hairy vetch weight and H. postica densities was high, whereas the interaction between the H. postica and B. anurus densities was very high. These results suggested that early timing and high density seeding indirectly enhanced the density of B. anurus by strong direct effects of the H. postica density on the B. anurus during the tri-trophic interaction. Overall, we concluded that a combination of early timing and high density hairy vetch seeding may facilitate efficient field productions of B. anurus

Evaluation of Black Soldier Fly (Hermetia illucens) Larvae and Pre-Pupae Raised on Household Organic Waste, as Potential Ingredients for Poultry Feed

Black soldier fly (BSF) larvae and pre-pupae could be satisfactorily raised on household organic waste and used as poultry feed, offering a potential sustainable way to recycle untapped resources of waste. The present study was conducted to determine if whole (non-defatted) BSF larvae and pre-pupae raised on experimental household waste could substitute soybean meal and oil as ingredients for laying hen diets. While no significant differences in feed intake and the egg-laying rate of hens were observed throughout the experiment, egg weight and eggshell thickness were greater in the pre-pupae-fed group than in the other groups. Moreover, although diversity of the cecal microbiota was significantly higher in the pre-pupae-fed than in the control group, no significant differences in bacterial genera known to cause food poisoning were observed when comparing the treatment groups. Nonetheless, Lactobacillus and Bifidobacterium populations were significantly lower in the treatment than in the control group. Fat content in BSF was possibly related with the changes in the cecal microbiota. Hence, since BSF fat was deficient in essential fatty acids, special attention should be paid to the fat content and its fatty acid composition in the case of regular inclusion of BSF larvae and pre-pupae oil as an ingredient in poultry diets