Yasir Iftikhar

Symptomatic expression of tristeza-infected citrus plants in Pakistan

Variable symptoms were recorded during a survey in the citrus trees infected or suspected to be infected with citrus tristeza virus based on ELISA tests. Sweet orange manifested main symptoms like bud union crease, pin holing, bark cracking, incompatibility, yellowing and dropping of leaves. Pin holing was particularly prevalent in Sweet orange (Citrus sinensis Osbeck), Kinnow (Citrus reticulata Blanco) and Grapefruit (Citrus paradisii Mcaf.), while incompatibility was only in Sweet orange and Grapefruit.

Toxicity of Botanicals and Conventional Insecticides to Aenasius bambawalei Hayat, an Endoparasitoid of Cotton Mealybug, Phenacoccus solenopsis Tinsley

Abstract. Insecticides with new chemistries and botanicals were evaluated against the parasitoid Aenasius bambawalei Hayat. Ninety-four percent of the parasitoids died after application of least concentrations and 100% died after greatest concentrations of malathion, dimethoate, and curacron. Ninety-six percent of parasitoids died from acetamiprid at greatest concentration. Botanicals were safer. Maximums of 34.4 and 23.2% of parasitoids were dead at 48 hours after applications of neem, Azadirachta indica A. Juss., and mint, Mentha longifolia (L.) Huds., respectively. Lesser concentrations of botanicals can be used to manage cotton mealybug, Phenacoccus solenopsis Tinsley, and have non-toxic effects on natural enemies.

Disease Severity Index as It Affects Responses in Potato Virus X–Challenged Potato Varieties

ABSTRACT Potato (Solanum tuberosum L.) is an important vegetable crop but can have significant yield loss due to disease, including those caused by viruses. The physiology of host plants can be affected by viruses, which can lead to symptom expression. Study of biochemical activities helps to understand the phenomena of plant disease resistance and can be useful in screening for natural resistance in host plants against viruses. Biochemical activities were analyzed among varieties from potato rated as being in susceptible (S), moderately susceptible (MS), and moderately resistant (MR) reaction groups on the basis of disease severity index. Reaction group status was confirmed through enzyme-linked immunosorbent assay (ELISA) of potato germplasm showing symptoms of potato virus X (PVX). Phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO), and sugar, soluble protein, and total amino acids contents were compared in virus-infected potato varieties from the reaction groups. There was not much variation in PAL activity among varieties in the same reaction group. The PPO and total sugar contents were lower in varieties of the MR reaction group compared to S varieties. Total soluble protein content was higher in S and MS varieties. Amino acid content was low in S and MS reaction groups. Comparison of biochemical analysis in varieties based on reaction groups against PVX could be helpful in selection of varieties for better yield.

Incidence of Spodoptera litura (Lepidoptera: Noctuidae) and Its Feeding Potential on Various Citrus (Sapindales: Rutaceae) Cultivars in the Sargodha Region of Pakistan

Abstract Spodoptera litura F. (Lepidoptera: Noctuidae) adversely affects important crops such as cotton, okra, tomato, potato, and pumpkin. For the first time, this species was observed in a citrus nursery in the Sargodha Region of Pakistan. The principal objectives of this study were to determine the effects of several citrus (Sapindales: Rutaceae) cultivars, including Citrus reticulata Blanco (Feutrells Early, Seedless Kinnow, and Fairchild mandarin orange) and Citrus paradisi Macfad. (grapefruit), on feeding by S. litura, and the effects of these plants on the growth of the insect. Based on performance of 3rd instars, Feutrells Early and Seedless Kinnow supported maximum relative growth rates, high efficiencies of conversion of ingested food, and high levels of leaf consumption and larval weight gain, relative to the other citrus cultivars. Values of these parameters were lowest on grapefruit. Thus, the mandarin oranges Feutrells Early and Seedless Kinnow were more susceptible to damage than grapefruit.