Chili pepper genotypes assay approach for resistance to Aphis gossypii (Hemiptera: Aphididae)

The cotton aphid (Aphis gossypii), is one of the most devastating insect pests for chili pepper that damages the crop and transmits several viruses. Thus far, there is no commercial chili cultivar with effective resistance to cotton aphids (CA). The present study aimed to develop a reliable and practical screening protocol in chili peppers for aphids resistance in the tropical areas. Three no-choice test methods i.e., seedling cage, detached leaf, and clip cage tests have been developed. The experiment was conducted in a randomized complete block design (RCBD) with four replications in a greenhouse at the Gunung Putri, Bogor, West Java, Indonesia. Seven chili pepper genotypes belong to the species Capsicum annuum L. provided by the Department of Agronomy and Horticulture, IPB University, Bogor, Indonesia were used in this study. Chili pepper resistance to aphids was observed through the number of aphids progeny, and aphids fecundity among the genotypes. Two chili genotypes consistently showed low infestation while other genotypes showed the highest infestation with three screening methods. All the methods have a high heritability value (90%–91%), indicating that the evaluated chili genotypes could be used to determine effective screening methods. The correlation between the detached leaf and clip cage tests was significant (r = 0.84, P ≤ 0.05). Therefore, the clip cage test could be used as a reliable and practical screening test for the assay of chili peppers resistance to CA infestation. These information will be helpful in the development of aphid resistant cultivars in the future.

Life cycle and morphometry of Rugose spiraling whitefly, Aleyrodicus rugioperculatus Martin (Hemiptera: Aleyrodidae) on coconut

The present study investigated the biology and morphometric analysis of rugose spiralling whitefly (RSW), Aleyrodicus rugioperculatus on coconut under mini net house condition at Department of Agricultural Entomology, Tamil Nadu Agricultural University-Coimbatore during 2019-2020. The biology of rugose spiralling whitefly was studied by clip cage method and morphometrics were done using Leica image analyser. Total lifecycle of rugose spiraling whitefly was 56.23 ± 2.20 days. Developmental period of egg, nymphal, pupal and adult period was 8.47 ± 0.26, 17.46 ± 0.76, 10.30 ± 0.29 and 20.00 ± 1.00 days, respectively. In morphometrics, Length and width of egg (0.31 ± 0.01 mm and 0.11± 0.02 mm), nymphal (0.94 ± 0.01 mm and 0.82 ± 0.01 mm), pupal (1.23 ± 0.01 mm and 1.00 ± 0.01 mm) was recorded. A nymphal parasitoid, Encarsia guadeloupae can be potential natural enemy for effective management of rugose spiraling whitefly.

Comparison of Toxicological Bioassays for Whiteflies

Two Bemisia tabaci populations from Georgia and Florida, USA, were tested for their response to insecticides across different toxicological bioassay methods. Five insecticides in four Insecticide Resistance Action Committee (IRAC) groups (imidacloprid (4A), dinotefuran (4A), flupyradifurone (4D), pyriproxyfen (7C) and cyantraniliprole (28)), were evaluated against a water check. The routes of application to the plant used were either leaf drench or (systemic) root drench. The four different whitefly bioassay methodologies tested were two published IRAC methods, a clip cage method, and a new tube method. A split–split experimental design was used to assess any interactions between application route, bioassay method and insecticide treatment. Application route had no significant effect on efficacy. However, bioassay method affected overall whitefly mortality, with the dish method having reduced mortality compared to other methods, except for the clip cage method. High rates of cyantraniliprole, dinotefuran and flupyradifurone insecticides resulted in the highest incidence of adult whitefly mortality. Significant interactions relative to percent adult mortality were found between the insecticide and bioassay method for both populations assayed. The clip cage method was more sensitive in terms of dose mortality response followed by the cup and tube methods. The dish method was the least responsive to insecticide dose. Other interactions are discussed.

Characterization of Local and Systemic Impact of Whitefly (Bemisia tabaci) Feeding and Whitefly-Transmitted Tomato Mottle Virus Infection on Tomato Leaves by Comprehensive Proteomics

Tomato mottle virus (ToMoV) is a single-stranded DNA (ssDNA) begomovirus transmitted to solanaceous crops by the whitefly species complex (Bemisia tabaci), causing stunted growth, leaf mottling, and reduced yield. Using a genetic repertoire of seven genes, ToMoV pathogenesis includes the manipulation of multiple plant biological processes to circumvent antiviral defenses. To further understand the effects of whitefly feeding and whitefly-transmitted ToMoV infection on tomato plants (Solanum lycopersicum ‘Florida Lanai’), we generated comprehensive protein profiles of leaves subjected to feeding by either viruliferous whiteflies harboring ToMoV, or non-viruliferous whiteflies, or a no-feeding control. The effects of whitefly feeding and ToMoV infection were measured both locally and systemically by sampling either a mature leaf directly from the site of clip-cage confined whitefly feeding, or from a newly formed leaf 10 days post feeding (dpf). At 3 dpf, tomato’s response to ToMoV included proteins associated with translation initiation and elongation as well as plasmodesmata dynamics. In contrast, systemic impacts of ToMoV on younger leaves 10 dpf were more pronounced and included a virus-specific change in plant proteins associated with mRNA maturation and export, RNA-dependent DNA methylation, and other antiviral plant processes. Our analysis supports previous findings and provides novel insight into tomato’s local and systemic response to whitefly feeding and ToMoV infection.

Effects of plant age, leaf age and virus yellows infection on the population dynamics of Myzus persicae (Homoptera: Aphididae) on sugarbeet in field plots

Field experiments in which clip-caged apterae of Myzus persicae (Sulzer) (Homoptera: Aphididae) were monitored on sugarbeet revealed that leaf age, plant age and infection of the host with beet yellows closterovirus (BYV) had very large effects on aphid performance (development, reproduction and survival). On healthy plants performance was much better on young, expanding heart leaves than on older leaves. Performance on senescent leaves was poor. When apterae were kept on young heart leaves all their lives (by moving clip-cages to younger leaves every 4 days) there was a strong negative relationship between aphid performance and plant age (measured as plant leaf number at birth). On plants inoculated with BYV apterae showed large improvements in performance. These occurred so rapidly that nymphs born at the time of virus inoculation could benefit as much as those born later. The sizes and between-leaf distributions of M. persicae populations which developed from standard numbers of colonists on whole plants in cages were consistent with the results of the clip-cage experiments. Alatae were less sensitive than apterae to differences in plant and leaf age. Implications of the results for BYV epidemiology and control are discussed.

Control of Adult Whitefly on Poinsettia Under Greenhouse Conditions, Winter 1992

Poinsettias obtained as rooted cuttings were potted in 15 cm pots and allowed 8 wk growth (10-12" tall) before use. Twenty-seven plants were treated by soil application and arranged in a randomized block design on a greenhouse bench. Forty DAT, a 2.5 cm diam clip-cage containing 20 adult SWF was placed on the abaxial side of a fully expanded leaf of each plant. Eight h later the adults were removed and clip-caged to a separate set of untreated plants. Live and dead adults were counted at transfer, 24, and 48 h after transfer.

A MODIFIED CLIP CAGE FOR USE WITH APHIDS AND OTHER SMALL INSECTS

Experimental ecologists have frequently used cages to facilitate their understanding of ecological systems. This has been particularly true of ecologists studying aphids and other small insects, and a variety of cage designs have been described, ranging from small screened tents to sleeve cages to clip cages (see Adams and van Emden, 1972). The purpose of this note is to describe a modified clip cage design that is suitable for use on irregular cylindrical surfaces as well as on leaves.

A Simplified Clip Cage for Aphid Investigations

At the Vancouver laboratory a large number of cages were needed to confine aphids to single leaves in virus transmission experiments. The cages had to be of simple construction, light, and easily manipulared. The cage developed was similar to that of MacGillivray and Anderson (1957), but was simpler to make, and the materials were easily obtained locally. The materials are: acrylic plastic tubing, metal hair-curl clips, foam rubber, corks to fit the tubing, and muslin.