Acquisition Access Feeding Period Research Articles

Studies on the transmission of Squash Leaf Curl China Virus causing yellow mosaic and leaf curl disease in pumpkin

Viruses pose a significant threat to pumpkin cultivation, leading to substantial yield losses and reduced fruit quality. Understanding the transmission dynamics and disease progression of Squash Leaf Curl China Virus (SLCCV), a major virus affecting pumpkin, will contribute to developing effective management strategies for this crop. Our study aimed to develop an efficient mechanical inoculation method for SLCCV in pumpkin and investigate whitefly transmission. Mechanical inoculation was assessed using different buffers (I, II, and III) for preparing the viral inoculum. Buffer III, consisting of phosphate buffer, β-mercaptoethanol, and Na2SO3, showed the highest severity of symptoms and incidence of infection in the susceptible pumpkin variety Pusa Vishwas. The summer season was the most favourable for virus transmission, and plant parts such as expanded leaves, middle leaves, and stems exhibited higher infectivity than other parts. A minimum of two whiteflies per plant successfully transmitted the virus to pumpkin plants, resulting in yellow mosaic symptoms and stunted growth. The transmission efficiency increased with an increase in number of whiteflies per plant. A minimum acquisition access feeding period (AAP) of 10 min. and an inoculation access feeding period (IAP) of 24 h were optimal for whitefly-mediated transmission of SLCCV. These findings highlight the importance of vector control strategies, such as insecticides and physical barriers to prevent whitefly-mediated transmission of SLCCV in pumpkin. This is the first report of sap transmission of SLCCV in pumpkin, emphasizing the importance of developing and implementing comprehensive control strategies that address all possible routes of infection.

Mesta yellow vein mosaic virus: application of loop-mediated isothermal amplification method to study efficiency of acquisition, retention and transmission by Bemisia tabaci (Hemiptera: Aleyrodidae) in Kenaf

Whitefly is an important pest and vector of many plant begomoviruses. Investigations were carried out to understand the acquisition, retention, transmission, and gender basis transmission efficiency of Mesta yellow vein mosaic virus (MeYVMV) by whitefly. The minimum acquisition access feeding period (AAFP) was 0.10 h which resulted in 11.1% infected plants. Based on LAMP assay and yellowing symptoms, 100% virus acquisition was achieved by whitefly with an exposure of 18 to 48 h. Virus was transmitted in tested plants up to 88.8% after 1 to 10 days retention time of viruliferous whiteflies, whereas no symptoms were observed after 35 days. Fifteen minutes of exposure to viruliferous whiteflies on healthy plants resulted in 11.1% transmission. Cent percent transmission of virus was achieved in plants with 12 h exposure period. Highest virus transmission efficiency of 55.60% was observed in female whitefly compared to 33.3% in single male whitefly. Present study shall help to understand the interaction of insect-plant–virus relationship, epidemiological knowledge, and formulation of management strategies against virus and its vector.

Virus-Vector Relationship of Bittergourd yellow mosaic virus and the Whitefly Bemisia tabaci Genn.

Bittergourd yellow mosaic virus (BGYMV) is one of the virus affecting the bittergourd (Momordica charantia). It is transmitted by whitefly Bemisia tabaci Genn. Minimum of five whiteflies were required to transmit the virus. However, hundred per cent transmission of BGYMV disease was obtained when 45 whiteflies were released per plant. Twelve hours of acquisition access feeding period (AAFP) and inoculation access feeding period (IAFP) were required for the whiteflies to transmit the disease. The percentage of transmission increased with increase in both acquisition and inoculation feeding period. A pre-acquisition starvation period of 3.5 h ensured hundred per cent transmission, while post-acquisition starvation period affected the transmission.

The route of tomato spotted wilt virus inside the thrips body in relation to transmission efficiency.

The route of tomato spotted wilt virus (TSWV) in the body of its vectors, Frankliniella occidentalis and Thrips tabaci (Thysanoptera: Thripidae) was studied during their development. First instar larvae were allowed, immediately upon hatching, to acquire virus from mechanically infected Datura stramonium plants for 24 h. The rate of transmission by adults was determined in inoculation access feeding test on Emilia sonchifolia leaf disks. Thrips tissues were analysed for infection at 24 h intervals after the acquisition-access feeding period, and assayed by the whole-mount immuno-fluorescent staining technique. The virus was initially detected in the proximal midgut region in larvae of both species, and then in the second and third midgut regions, foregut, and salivary glands. Occasionally the first infections of the salivary glands were already detected in one-day-old second stage larvae. The intensity of the infection in the various organs of the thrips of each species was positively related to the transmission efficiency. In both thrips populations good agreement was found between the percentage of second instar larvae and adults with at least one infected salivary gland lobe and the percentage of transmitting adults. These results support the contention that the virus must reach the salivary glands before thrips pupation in order to be transmitted by old second instar larvae and adults.

Spatial and Temporal Distribution of Geminiviruses in Leafhoppers of the Genus Cicadulina Monitored by Conventional and Quantitative Polymerase Chain Reaction

ABSTRACT Spatial and temporal distribution of Maize streak virus (MSV, family Geminiviridae, genus Mastrevirus) was monitored in the vector species Cicadulina mbila and the nonvector species C. chinaï using conventional and real-time quantitative polymerase chain reaction. Sustained feeding on MSV-infected plants showed that virus accumulation reaches a maximum in C. chinaï, but not in C. mbila. After a 3-day acquisition access feeding period (AAP), MSV was detected in the gut, the hemolymph, and the head of C. mbila, but only in the gut of C. chinaï. Similarly, Digitaria streak virus (genus Mastrevirus), which is not transmitted by either of the two species, was only detected in the gut. MSV was detected in the hemolymph of C. mbila 3 h after the beginning of the AAP. Although viral DNA progressively decreases in the vector and nonvector species after a 3-day AAP, MSV DNA remained stable in the salivary glands of C. mbila.

Study of semipersistent transmission of beet yellows virus by the green peach aphid, Myzus persicae Sulz.

The optimal conditions for beet yellows virus (BYV) acquisition and transmission by Myzus persicae Sulz. were studied. Maximum recorded retention of BYV in aphids was 48 h. Preacquisition starvation of aphids influenced positively transmission efficiency if the acquisition access feeding period was short (30 min to 2 h), but after a longer such period it was without influence. The efficiency of transmission also depended on the acquisition access feeding period. Maximum transmission efficiency of starved and nonstarved aphids occurred after 2 h (75%) and 4–6 h (65%) of acquisition, respectively.

A Novel Method for Tospovirus Acquisition by Thrips

An in vitro feeding method for the acquisition of impatiens necrotic spot tospovirus (INSV) and tomato spotted wilt tospovirus (TSWV) by western flower thrips (Frankliniella occidentalis (Pergande) was developed. This is the first system developed in which tospovirus viability was maintained in an in vitro technique specifically designed for thrips feeding. Three-day-old larvae of western flower thrips were caged in a cylindrical plastic tube with Parafilm membrane covering both ends. Leaf extracts from INSV- and TSWV-infected Nicotiana benthamiana or Datura stramonium were prepared. Following one cycle of differential centrifugation, the extract was placed on the membrane on one end of the cage. A second membrane was placed over the first membrane thus covering the extract. After a 24-h acquisition access feeding period, thrips were kept on green-bean pods in a container until they were 10-dayold adults. Enzyme-linked immunosorbent assays (ELISA) showed that acquisition feeding of virus suspensions prepared from infected plant hosts resulted in thrips testing positive for viruses. Cohorts from these ELISA-positive thrips were shown to be viruliferous when placed onto virus-susceptible host plants. This in vitro method is an important tool in the study of tospovirus/thrips interactions

Localization of Virus-like Particles in the Foreguts of Viruliferous Graminella nigrifrons Leafhoppers Carrying the Semi-persistent Maize Chlorotic Dwarf Virus

SUMMARY The leaf hopper Graminella nigrifrons transmits maize chlorotic dwarf virus(MCDV) in a semi-persistent manner and loses its ability to inoculate plants following ecdysis. Virus-like particles (VLP) resembling MCDV in purified preparations and in MCDV-infected plants were observed by electron microscopy adhering to the cuticula lining the precibarium, cibarium (sucking pump), pharynx and fore-oesophagus in viruliferous leaf hoppers carrying MCDV. No VLP were observed in the alimentary canal beyond the cardiac valve, in any organ or tissue in the haemocoele, or in the maxillary salivary duct. No VLP were observed associated with the stylet tips or anywhere on the cuticula surfaces of either the mandibular or maxillary stylets. The VLP were not found associated with the cuticula lining of the foregut in a similarly treated non-vector species, Dalbulus maidis, or in vector or non-vector species given either a 48 h acquisition access feeding period on MCDV-infected source plants followed by a 48 h post-acquisition feeding on healthy plants (renders inoculative leaf hoppers non-inoculative) or solely a 48 h feeding on healthy plants. No differences were observed between MCDV-inoculative and non-inoculative Graminella given similar access to virus. The VLP occurred in thin layers or small to large clusters embedded in a lightly stained matrix material (m-material) or a densely stained substrate which, in turn, were apparently attached by m-material to the cuticula. It is thought that the VLP are those of MCDV and that the m-material, which resembles materials previously reported in association with virus-binding sites in the fore alimentary canals of aphid and nematode vectors, functions in binding virus to retention sites on the vector’s cuticula.

Aphid Transmission and Separation of Two Strains of Sweet Potato Feathery Mottle Virus from Sweet Potato12

The russet crack strain of sweet potato feathery mottle virus (RC-FMV) is transmitted by Aphis gossypii Glover in a typical nonpersistent fashion. The minimum acquisition and inoculation probe times resulting in successful transmission were 7 and 2 sec, respectively. The virus was retained by starved aphids for at least 60 min. No transmission occurred when the aphids were starved for 120 min after a virus acquisition access feeding period of 4 min. Transmission of RC-FMV from sweet potato plants was greatest when symptomatic foliage was used as a virus source; no transmission occurred from young, expanding foliage at the plant apex. Mixed infections of the common strain of sweet potato feathery mottle virus (C-FMV) and the RC-FMV strain in sweet potato were readily detected and the component viruses were isolated by using aphid transmission from graft-inoculated Ipomoea setosa Ker. plants to I. nil (L.) Roth seedlings. Mixed infections were not detected by aphid transmission directly from sweet potato.

ツマグロヨコバイによるイネわい性症状の媒介について

Stunted rice plants were observed in rice growing areas of West Kyushu in 1971. Since then, the affected acreage has increased year by year, accompanying severe yield losses. Field observations and experiments were conducted to ascertain a causal organism in 1973. Plant- and leafhopper adults were fed on the healthy rice plants for a 3-day inoculation access feeding period following a 3-day acquisition access feeding period on naturally-infected rice plants. Of the four species tested, Nephotettix cincticeps was found to be capable of transmitting the disease. N. cincticeps was also able to transmit the causal agent to healthy rice seedlings from the experimentally-infected plants after a 2-day acquisition and a 1-day inoculation access feeding period. When the rice seedlings of 1- to 2-leaf stage were infected, symptoms were clear and distinguishable. In addition. infective specimens were detected among the field populations of N. cincticeps by the transmission tests. The mode of transmission was likely to be of semi- or nonpersistent type. There is strong evidence at present that the causal agent is a virus, which would be new one at least in Japan.