Competition of insect decomposers over large vertebrate carrion: Necrodes beetles (Silphidae) vs blow flies (Calliphoridae)

Large carrion is inhabited by highly variable and interactive communities of insects. Positive interactions in carrion insect communities have been recently the focus in carrion ecology. By contrast, competition between carrion insects is rather undervalued. Here we provide evidence that blow flies (Calliphoridae) and Necrodes beetles (Silphidae), dominant decomposers of large carcasses in terrestrial habitats, compete over carrion. By reanalysing the results from 90 pig carcasses we demonstrated that the contribution of the flies and the beetles to the decay was negatively related. The greater part of the large carrion pool was monopolised by blow flies, whereas Necrodes beetles abundantly colonized carcasses, on which blow flies were less effective as decomposers. In behavioural assays, we found that adult beetles killed four times more frequently feeding than postfeeding third instar larvae of the flies, with the large decrease in the killing frequency after the larvae reached the age of early third instar. Therefore, adult Necrodes beetles preferentially killed the larvae that were before or in their peak feeding. The study provides evidence that the interaction between blow flies and Necrodes beetles is a combination of indirect exploitative effects of the flies and direct interference effects of the beetles (the mixed competition).

Impact of Four Plant Extracts on Bactrocera dorsalis a Pest on Fruits

Menthol extracts of four local plants (Ocimum tenuiflorum, Hibiscus, Mentha longifolia and Bougainvillea glabra) were analysed to check their toxicity on third instar larvae of B. dorsalis by estimating the larval mortality for four plant extracts and different times exposure (1-5 hr) and measured LT50 value for each plant extract. Larval mortality varies for extract of each studied plant as Ocimum tenuiflorum showed its highest value of 56.68% at 4.57hr, for hibiscus it was 72% at 3.5 hr., for Mentha longifolia it was 95.23% at 4 hr., while for Bougainvillea glabra it was 100% at 2 hr. exposure. The LT50 values for B. dorsalis varying from 1.011 for Bougainvillea glabra to 2.946 for Ocimum tenuiflorum whereas LT50 values were 1.402 and 1.123, forHibiscus and Mentha longifolia respectively. Present study results showed that Bougainvillea glabra was highly toxic whereas Ocimum tenuiflorum shows least toxicity.

Regulated inositol synthesis is critical for balanced metabolism and development in Drosophila melanogaster

ABSTRACT Myo-inositol is a precursor of the membrane phospholipid, phosphatidylinositol (PI). It is involved in many essential cellular processes including signal transduction, energy metabolism, endoplasmic reticulum stress, and osmoregulation. Inositol is synthesized from glucose-6-phosphate by myo-inositol-3-phosphate synthase (MIPSp). The Drosophila melanogaster Inos gene encodes MIPSp. Abnormalities in myo-inositol metabolism have been implicated in type 2 diabetes, cancer, and neurodegenerative disorders. Obesity and high blood (hemolymph) glucose are two hallmarks of diabetes, which can be induced in Drosophila melanogaster third-instar larvae by high-sucrose diets. This study shows that dietary inositol reduces the obese-like and high-hemolymph glucose phenotypes of third-instar larvae fed high-sucrose diets. Furthermore, this study demonstrates Inos mRNA regulation by dietary inositol; when more inositol is provided there is less Inos mRNA. Third-instar larvae with dysregulated high levels of Inos mRNA and MIPSp show dramatic reductions of the obese-like and high-hemolymph glucose phenotypes. These strains, however, also display developmental defects and pupal lethality. The few individuals that eclose die within two days with striking defects: structural alterations of the wings and legs, and heads lacking proboscises. This study is an exciting extension of the use of Drosophila melanogaster as a model organism for exploring the junction of development and metabolism.

Identification of larvae of two Aphodius Helwig, 1798 (Coleoptera: Scarabaeidae: Aphodiinae) species using morphology and DNA barcode

The third instar larvae of Aphodius (Alocoderus) hydrochaeris (Fabricius, 1798) and A. (Bodilus) ictericus (Laicharting, 1781) are described based on scanning electron microscopy and COI sequences. COI barcode sequence for A. (A.) hydrohaeris is provided for the first time. Two haplotypes are discovered in A. (B.) ictericus.

Description of the second- and third-instar larvae of Hydrovatus crassulus Sharp, 1882 (Coleoptera: Dytiscidae: Hydrovatini)

The second- and third-instar larvae of the diving-beetle species Hydrovatus crassulus Sharp, 1882 are described and illustrated, including detailed morphometric and chaetotaxic analyses of the cephalic capsule, head appendages, legs, last abdominal segment and urogomphi. Larvae of this species lack the parietal pore PAo, the premental seta LA3 and the urogomphal seta UR8, and have the sensillum MN2 shaped as a short hair-like seta and the ventral surface of the abdominal segments II–V sclerotized. All these characteristics are shared with the other species of Hydrovatus Motschulsky, 1853 known in detail (H. caraibus Sharp, 1882) and therefore are considered diagnostic for the genus. Hydrovatus crassulus also characterizes by the presence of a small galea, which reinforces the hypothesis that this structure is part of the ancestral condition of Hydrovatus. Larvae of H. crassulus differ from those of H. caraibus in having a smaller size, a smaller ratio U/LAS, and a larger ratio U1/U2, and also in the presence (in most cases) of a secondary seta on the anteroventral surface of femur.

Divergence of Cultivable Bacteria Associated with Larvae and Adult Bactrocera dorsalis (Diptera: Tephritidae) Laboratory-Reared Strains

Insects entertain intricate and mutualistic relationship with an array of microorganisms, which significantly influence their fitness, ecology and evolution. In recent decades, there has been increasing interest toward studying the effects of microbiome on many host insects (Dipterans, Lepidopterans, and Coleopterans). Studies so far realized indicate that gut microbiome contribute to host nutritional ecology, defense, immunity and lifespan. Bactrocera dorsalis (Tephritidae: Diptera) is a polyphagous fruit fly which attacks a huge variety of fruits and vegetables worldwide and has been placed as a quarantine species by many countries. To investigate the specific functions of the gut endosymbionts, it is a prerequisite to know the composition of gut bacterial communities whose manipulation will help to decipher their ecological relevance. Here, we used the culture-dependent technique to isolate and identify gut bacteria from B. dorsalis at different developmental stages. The results revealed 11 bacterial species from the third instar larvae, 18 and 12 from female and male populations, respectively. These bacteria were assigned to six families, namely, Enterobacteriaceae, Enterococcaceae, Staphylococcaceae, Streptococcaceae, Micrococcaceae and Bacillaceae. Bacterial species from these families were differentially represented in various samples, except Klebsiella oxytoca , Enterobacter cloacae, Pantoea dispers and Enterococcus faecalis that were detected at all developmental stages. Overall, Enterobacteriaceae was the most dominant family in females and third instar larvae accounting for 57.89% and 26.32%, respectively, while Enterococcaceae was dominant in males with 75% of the total bacterial taxa. These results suggest that B. dorsalis possesses a huge variety of cultivable bacteria that could be used to explore their specific functions on host physiology and fitness.

Larvicidal toxicity and parasporal inclusion of native Bacillus thuringiensis BK5.2 against Aedes aegypti

Objectives Native Bacillus thuringiensis BK5.2, isolated from soil of Baluran National Park, East Java, Indonesia, has been shown to be toxic against Aedes aegypti larvae. This study aims to determine the strength and the speed of the toxicity of B. thuringiensis BK5.2 against A. aegypti larvae in lethal concentration (LC) and lethal time (LT), as well as detection of toxin structure and parasporal inclusion. Methods LC values were determined by the mortality of A. aegypti third instar larvae after 24 and 48 h exposure to five various concentrations of B. thuringiensis BK5.2, while LT values were determined based on the mortality of A. aegypti third instar larvae due to exposure to LC90 concentration at 0; 0.5; 1; 2; 4; 8; 10; 20; 24; and 48 h. Larvicidal toxicity was determined based on value of LC50 and LC90 (CFU/mL), as well as LT50 and LT90 (hours) analysed ​​with Probit analysis. Parasporal inclusion was detected using transmission electron microscope (TEM) and scanning electron microscope (SEM). Results Based on bioassay, LC50 and LC90 values ​​were 11.6 × 106 and 22.7 × 106 CFU/mL, respectively, at 24 h exposure, as well as 8.3 × 106 and 15.4 × 106 CFU/mL, respectively, at 48 h exposure, while the value of LT50 and LT90 were 19.0 and 26.6 h, respectively. Morphological observation of the dead larvae showed there was damage on abdomen and thorax region. Detection by TEM and SEM showed there was cuboidal parasporal inclusion. Conclusions Native B. thuringiensis BK5.2 has high toxicity against A. aegypti larvae and detected flatcuboidal toxin in parasporal inclusion.

FIRST RECORD OF Brachymeria podagrica (HYMENOPTERA: CHALCIDIDAE) AS PARASITOID OF Peckia collusor (DIPTERA: SARCOPHAGIDAE)

In this work, the wasp Brachymeria podagrica is recorded for the first time for Colombia, a solitary parasitoid of larvae of the Peckia collusor fly. Third instar larvae of P. collusor were exposed to outdoor ambient conditions for 6 hours in the garden of the Tecnológico de Antioquia (Medellín, Colombia). 29 B. podagrica adults were obtained from the host pupae. Prevalence of parasitism was 14.5 %.