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Bemisia tabaci Gennadius (Homoptera: Aleyrodidae) is the most devastating insect-pest in cotton crop. It is vector of the cotton leaf curl virus (CLCV) and is responsible for huge losses to cotton industry in Pakistan and worldwide. It is mainly controlled by insecticides but the injudicious use of insecticides has resulted in insecticide resistance and population resurgence in addition to various harmful effects on the humans, non-target organisms and the environment. Transgenerational studies are very helpful to choose a best insecticidal option. In the current study, age-stage two-sex life table analysis was used to identify transgenerational effects of sublethal doses of afidopyropen. The adults of B. tabaci were treated with three concentrations of afidopyropen i.e., LC10, LC30 and LC50. The results indicated significant changes in the progeny i.e. the fecundity decreased in treated population; and female and male longevity of their progeny were more in control as compared to treated populations. Similarly, population parameters like intrinsic rate of growth (r), net reproductive rate (R0) and limiting rate of growth (λ) were significantly decreased in the treated adult progeny with values of 0.08–0.11, 4.85–7.46 and 1.09–1.12 per day, respectively. Based on the reduced biotic potential, afidopyropen can be suggested as an effective alternative option for the management of B. tabaci. [ABSTRACT FROM AUTHOR]

Cotton leaf curl disease (CLCuD) is a major constraint in the production of cotton crop across the Africa and Asia which is caused by a complex of begomoviruses (family Geminiviridae). Cotton leaf curl Khokhran virus and associated Cotton leaf curl Multan betasatellite (CLCuKoV/CLCuMB) complex are important agents of CLCuD which transmitted by whiteflies of the Bemisia tabaci species complex. Information regarding the transmission efficiency of CLCuKoV/CLCuMB by whitefly cryptic species is seriously lacking in Pakistan, therefore present study is conducted for comparison of transmission efficiency of CLCuKoV/CLCuMB by two characterized whitefly cryptic species (Asia II-1 and Asia II-5). Whitefly cryptic species were reared separately on Nicotiana benthamiana plants infected with CLCuKoV/CLCuMB for 24 or 48 h and these infected whitefly cryptic species were transferred to un-infected cotton and alternative host plants for 24 or 48 h. The first experiment results showed that Asia II-1 was able to transmit CLCuKoV/CLCuMB with high efficiency in cotton and bitter gourd plants as compared to the Asia II-5 while other host plants did not develop symptoms. Further in the second experiment results revealed that Asia II-1 was able to transmit CLCuKoV/CLCuMB with high efficiency from symptomatic bitter gourd to cotton plants as compared to Asia II-5 which did not show symptoms of transmission. Infection symptoms were confirmed by visual inspection after 30 days and PCR analysis. We found the percentage of virus infection symptoms in alternate host plants differed between two whitefly cryptic species due to varying transmission efficiencies. This research finding advances our understanding to explore the whitefly cryptic species involved in the transmission of CLCuD and will aid in the development of management strategies for control of whitefly cryptic species and CLCuD transmission in Pakistan. [ABSTRACT FROM AUTHOR]

In recent decades, Pakistan has suffered a decline in cotton production due to several factors, including insect pests, cotton leaf curl disease (CLCuD), and multiple abiotic stresses. CLCuD is a highly damaging plant disease that seriously limits cotton production in Pakistan. Recently, genome editing through CRISPR/Cas9 has revolutionized plant biology, especially to develop immunity in plants against viral diseases. Here we demonstrate multiplex CRISPR/Cas-mediated genome editing against CLCuD using transient transformation in N. benthamiana plants and cotton seedlings. The genomic sequences of cotton leaf curl viruses (CLCuVs) were obtained from NCBI and the guide RNA (gRNA) were designed to target three regions in the viral genome using CRISPR MultiTargeter. The gRNAs were cloned in pHSE401/pKSE401 containing Cas9 and confirmed through colony PCR, restriction analysis, and sequencing. Confirmed constructs were moved into Agrobacterium and subsequently used for transformation. Agroinfilteration in N. benthamiana revealed delayed symptoms (3–5 days) with improved resistance against CLCuD. In addition, viral titer was also low (20–40%) in infected plants co-infiltrated with Cas9-gRNA, compared to control plants (infected with virus only). Similar results were obtained in cotton seedlings. The results of transient expression in N. benthamiana and cotton seedlings demonstrate the potential of multiplex CRISPR/Cas to develop resistance against CLCuD. Five transgenic plants developed from three experiments showed resistance (60−70%) to CLCuV, out of which two were selected best during evaluation and screening. The technology will help breeding CLCuD-resistant cotton varieties for sustainable cotton production. [ABSTRACT FROM AUTHOR]