A genetically enhanced sterile insect technique against the fruit fly, Bactrocera dorsalis (Hendel) by feeding adult double-stranded RNAs

Abstract

RNAi based sterile insect technique (SIT) is an authentic insect management approach but requires proper target genes. During this study, spermless males were developed by interfering with germ cell differentiation and azoospermia related genes. Data demonstrates significant reductions in the target genes expressions (boul, zpg, dsx M, fzo and gas8) after oral dsRNAs administration. Knock down of target genes significantly affected the reproductive ability of males and reduced egg-hatching as compared to the control group. Furthermore, different combinations of selected gene dsRNAs (boul + zpg, boul + dsx M and zpg + dsx M) were made, which resulted up to 85.40% of male sterility. The most effective combination was selected to prepare different concentrations of dsRNA, 250, 500, 750 and 1000 ng/μl, that caused 18.97%, 38.68%, 58.02% and 85.40% male sterility, respectively. Subsequently, 1000 ng/μl of the same combination of ds-RNAs was used against differently aged adult flies (1, 5, 7, 10 days) which lead to 85.40%, 31.42%, 21.76% and 9.90% male sterility, respectively. SIT developed in this study showed that, boul + zpg combination of dsRNA feeding for 6 hours significantly reduced the number of spermatozoa and viability of sperm in 1-day-old B. dorsalis flies. In short, this study provides an effective SIT technique for long-term B. dorsalis management.

RNA Interference-Mediated Knockdown of Male Fertility Genes in the Queensland Fruit Fly Bactrocera tryoni (Diptera: Tephritidae)

“…Our experimental results demonstrate for the first time that RNAi is both operational and systemic in B. tryoni , as the ingested dsRNA traversed from the gut to the gonad to knock down testis-specific transcripts. This is not entirely surprising, as systemic RNAi has been observed in other tephritids [ 19 , 20 ]. At least two of the three dsRNAs (targeting tssk1 and trxt ) induced a significant knockdown of the target transcripts within the testis after three consecutive days of dsRNA feeding.…”

“…RNA interference (RNAi) knockdown technologies could potentially provide an alternative sterilization approach for those species that demonstrate any negative impacts from radiation treatments. RNAi, which is a sequence-specific post-transcriptional gene silencing process elicited by double-stranded RNA (dsRNA), has been used recently to sterilize or significantly reduce the fecundity of male mosquitoes [ 16 , 17 , 18 ] and fruit flies [ 19 , 20 ], and could provide a means of mass producing sterile males without adversely affecting other aspects of their physiology. The effectiveness of this approach will be dependent upon the development of easy and affordable methods of administering the dsRNA to a large number of insects.…”

“…In the Oriental fruit fly B. dorsalis , ingested dsRNA knocked down transcript levels more than 90% [ 19 , 20 ], including genes associated with spermatogenesis. Spermatogenesis genes are obvious candidates to sterilize male insects when targeted with RNAi.…”

“…Ingested dsRNA has been observed to knock down gut-specific transcripts in B. dorsalis larvae [ 28 ]. However, feeding spermatogenesis-specific dsRNAs to B. dorsalis has previously only been attempted in adults [ 19 , 20 ]. In B. tryoni , the pupation period is quite lengthy (~10 days), and effective RNAi-mediated knockdown of spermatogenesis gene transcripts would therefore require persistence of the dsRNA within the developing insects for almost three weeks.…”

Irradiation effect on the structure of bacterial communities associated with the oriental fruit fly, Bactrocera dorsalis

“…Traditionally B. dorsalis control has been based on insecticides, but concerns about environmental pollution, undesirable chemical residues, and negative impact on human health, plus the preservation of biodiversity demand new strategies to keep the pest population limited (Ali et al, 2017). For several major insect pests, such as fruit flies, tsetse flies, screwworms, mosquitoes, and certain caterpillars, the environment-friendly sterile insect technique (SIT) has been applied as a component of area-wide integrated pest management (AW-IPM) programs (Dyck et al, 2006).…”