Development In Aedes Albopictus Research Articles

Pathogenicity of entomopathogenic fungi to eggs, larvae, and adults and their effects on development of Aedes albopictus

Abstract. Ramayanti I, Herlinda S, Muslim A, Hasyim H, Anwar C, Suwandi S, Damiri N, Irsan C, Verawaty M. 2023. Pathogenicity of entomopathogenic fungi to eggs, larvae, and adults and their effects on development of Aedes albopictus. Biodiversitas 24: 4766-4774. No information is available on the effect of fungi on the development of Aedes albopictus and the effectiveness of fungi in killing its eggs, larvae, and adults. The aim of this research was to determine the pathogenicity of entomopathogenic fungi on the eggs, larvae, and adults of Ae. albopictus and to investigate the effects of the fungi on the development of Ae. albopictus. The fungal species identified molecularly were Aedes albopictus, Beauveria bassiana, Metarhizium anisopliae, Penicillium citrinum, and Talaromyces diversus. The results showed that entomopathogenic fungi negatively affected the development of Ae. albopictus and could decrease the eggs laid by adult females and shorten adult longevity. M. anisopliae was the most pathogenic fungal species (mortality rate 100%) for eggs, larvae, pupae, and adults of Ae. albopictus. However, B. bassiana, P. citrinum, and T. diversus were also found pathogenic to them. The effect of eggs treated with entomopathogenic fungi negatively affected the larval, pupal, and adult stages of Ae. albopictus. These findings highlighted that M. anisopliae, B. bassiana, P. citrinum, and T. diversus have insecticidal activity against Ae. albopictus eggs, larvae, pupae, and adults. Therefore, further investigation is needed to develop these fungal species into ovicides, larvicides, and adulticides to control Ae. albopictus.

Effects of Guangzhou seasonal climate change on the development of Aedes albopictus and its susceptibility to DENV-2.

The susceptibility of Asian tiger mosquitoes to DENV-2 in different seasons was observed in simulated field environments as a reference to design dengue fever control strategies in Guangzhou. The life table experiments of mosquitoes in four seasons were carried out in the field. The susceptibility of Ae. albopictus to dengue virus was observed in both environments in Guangzhou in summer and winter. Ae. albopictus was infected with dengue virus by oral feeding. On day 7 and 14 after infection, the viral load in the head, ovary, and midgut of the mosquito was detected using real-time fluorescent quantitative PCR. Immune-associated gene expression in infected mosquitoes was performed using quantitative real-time reverse transcriptase PCR. The hatching rate and pupation rate of Ae. albopictus larvae in different seasons differed significantly. The winter hatching rate of larvae was lower than that in summer, and the incubation time was longer than in summer. In the winter field environment, Ae. albopictus still underwent basic growth and development processes. Mosquitoes in the simulated field environment were more susceptible to DENV-2 than those in the simulated laboratory environment. In the midgut, viral RNA levels on day 7 in summer were higher than those on day 7 in winter (F = 14.459, P = 0.01); ovarian viral RNA levels on day 7 in summer were higher than those on day 7 in winter (F = 8.656, P < 0.001), but there was no significant difference in the viral load at other time points (P > 0.05). Dicer-2 mRNA expression on day 7 in winter was 4.071 times than that on day 7 in summer: the viral load and Dicer-2 expression correlated moderately. Ae. albopictus could still develop and transmit dengue virus in winter in Guangzhou. Mosquitoes under simulated field conditions were more susceptible to DENV-2 than those under simulated laboratory conditions.

Effects of long-term cadmium exposure on trehalose metabolism, growth, and development of Aedes albopictus (Diptera: Culicidae)

Trehalose is the major blood sugar in insects; it not only serves as an energy source but also plays important roles in physiological responses to adverse conditions. However, only a few studies have explored the effects of heavy metal exposure stress on trehalose metabolism in insects. Therefore, in this study, we examined the effects of cadmium stress on changes in trehalose metabolism in Aedes albopictus. Three concentrations of cadmium (0.005, 0.01, and 0.1 mg/L) were selected for evaluation of long-term stress in Ae. albopictus (from eggs to adults); Ae. albopictus in double-distilled water was used as the control group. The trehalose and glucose contents, trehalase activity, and trehalose metabolism-related gene expression were determined. The effects of long-term cadmium exposure on growth, development, and reproduction were also assessed. Trehalose contents were increased, whereas glucose contents and trehalase activity were decreased in Ae. albopictus following long-term exposure to low concentrations of cadmium compared with those in untreated individuals. Moreover, the expression of trehalose-6-phosphate synthase was upregulated, and that of trehalase was downregulated, indicating that Ae. albopictus may enhance trehalose synthesis to resist cadmium stress. Cadmium exposure also caused Ae. albopictus individuals to become smaller with a longer developmental duration, whereas both reproduction and hatching rates of the offspring were decreased compared with those in the control group. Our findings demonstrated that cadmium exposure affected the morphology, physiology, and biochemistry of Ae. albopictus. These findings also confirmed the role of trehalose in the response of Ae. albopictus to cadmium stress, providing insights into the effects of heavy metal stress on trehalose metabolism in an insect model.

Two of the three Transformer-2 genes are required for ovarian development in Aedes albopictus

In Drosophila melanogaster, transformer-2 (tra2) plays an essential role in the sex-specific splicing of doublesex (dsx) and fruitless (fru), two key transcription factor genes that program sexual differentiation and regulate sexual behavior. In the present study, the sequences and expression profiles of three tra2 (Aalbtra2) genes in the Asian tiger mosquito, Aedes albopictus (Ae. albopictus) were characterized. Phylogenetic analysis revealed that these paralogs resulted from two duplication events. The first occurred in the common ancestor of Culicidae, giving rise to the tra2-α and tra2-β clades that are found across divergent mosquito genera, including Aedes, Culex, and Anopheles. The second occurred within the tra2-α clade, giving rise to tra2-γ in Ae. albopictus. In addition to the conserved RNA recognition motif (RRM), arginine-rich/serine-rich regions (RS domains) and a linker region, a glycine-rich region located between the RRM and RS2 was observed in Tra2-α and Tra2-γ of Ae. albopictus that has not yet been described in the Tra2 proteins of dipteran insects. Quantitative real-time PCR detected relatively high levels of transcripts from all three tra2 paralogs in 0–2 h embryos, suggesting maternal deposition of these transcripts. All three Aalbtra2 genes were highly expressed in the ovary, while Aalbtra2-β was also highly expressed in the testis. RNAi-mediated knockdown of any or all Aalbtra2 genes did not result in an obvious switch of the sex-specificity in dsx and fru splicing in the whole-body samples. However, knockdown of transcripts from all three tra2 genes significantly reduced the female isoform of dsx mRNA and increased the male isoform of the dsx mRNA in both the ovary and the fat body in adult females. Furthermore, knockdown of either Aalbtra2-α or Aalbtra2-γ or all three Aalbtra2 led to a decrease in ovariole number and ovary size after a blood meal. Taken together, these results indicate that two of the three tra2 genes affect female ovarian development.

Developmental expression and oxidative stress induction of proteome of glutathione S-transferases in Aedes albopictus (Diptera: Culicidae)

The combination of proteomic approach and affinity chromatography (GSTrap™ HP) has been used to identify and investigate the differential expression of GSTs under toxic challenge and during the course of development in Aedes albopictus. There were multiple isoforms of glutathione transferases (GSTs) expressed in the three developmental stages of Aedes albopictus. On a 2D gel map, the results indicate that there were 19 spots with a molecular mass in the range of 24–30kDa. Three types of GSTs were identified from the spots; namely GSTS1, GSTD1, and GST Theta. Spots identified as GSTS1 and GSTD1 were further designated as GSTS1–1 to GSTS1–5 and GSTD1–1 to GSTD1–13 respectively. Isoforms GSTD1–10, GSTD1–11, GSTD1–12, GSTD1–13, and GSTT were absent in the adult life stage. Isoenzymes GSTS1–3, GSTD1–2, and GSTD1–6 appeared as the major expressed isoforms in all the life stages. The effect of free radical generators such as hydrogen peroxide and paraquat on the expression of the GST isoforms in larvae mosquitoes was also investigated. Isoforms GSTD1–1, GSTD1–4, GSTS1–4, and GSTD1–12 had >1.5 fold increase when the larvae were challenged with both chemicals. GSTS1–3, GSTS1–4, GSTD1–1, GSTD1–2, GSTD1–3, GSTD1–6, and GSTD1–12 were significantly expressed (p<0.05) with >1.5 fold change when the larvae were challenged with hydrogen peroxide. On the contrary, different GST isoforms were responsive towards paraquat challenge. Those isoforms were GSTS1–2, GSTS1–4, GSTD1–1, GSTD1–5, GSTD1–9, GSTD1–11, GSTD1–12, and GSTT (with >1.5 fold change). The purified larvae GSTs seemed to have limited substrate specificities with the ability to only conjugate 1-chloro-2,4-dinitrobenzene (CDNB) and 1,2-dichloro-4-nitrobenzene (DCNB). The GSTs have however shown that they were capable of detoxifying lipid peroxidation products and possessing glutathione peroxidase activities.

Effects of a copepod predator on the survivorship and development of Aedes albopictus (Diptera: Culicidae)

Effects of a copepod predator on the survivorship and development of Aedes albopictus (Diptera: Culicidae)

Laboratory and field evaluation of metallic copper on Aedes albopictus (Diptera: Culicidae) larval development.

Laboratory bioassays and field trials were carried out to study the effect of metallic copper on the development of Aedes albopictus (Skuse). Multiwire electric cable was used as a source of metallic copper. Three different doses were used in laboratory tests (5, 10, and 20 g/liter) and two in field tests (20 and 40 g/liter). In the laboratory, 10 g/liter induced high mortality and a lack of development in Ae. albopictus larvae and doses of 20 g/liter completely inhibited development. Larval mortality was higher in earlier instars than in third through fourth instars and pupae. No effects were reported on egg hatching. Copper ion concentration in water increased up to 574 ppb for 5 g/liter dose, 710 ppb for 10 g/liter dose, and 1,210 ppb for 20 g/liter dose, within week 6. The increasing concentration of copper in water was correlated positively with the decreasing production of adults. Copper ions concentration < 500 ppb did not or only slightly affected larval development and mortality of Ae. albopictus in laboratory tests. Copper concentrations between 500 and 1,000 ppb delayed larval development and caused high mortality. Copper concentrations > 1,000 ppb inhibited larval development completely killing all the larvae. This last result has been achieved by the use of a 20 g/liter dose of metallic copper in water. Copper also affected adult weight. In field trials, 20 g/liter reduced the number of larvae in treated pots by 90%, and 40 g/liter completely prevented oviposition. Moreover, the persistence of the toxic action of metallic copper in the field lasted for several months.