Muhammad Irfan Ullah

Non Target Effect of Cry1 Ab and Cry Ab x Cry3 Bb1 Bt Transgenic Maize on Orius insidiosus (Hemiptera: Anthocoridae) Abundance

Non-target effects of Cry1Ab x CP4 EPSPS and Cry1Ab+Cry3Bb1×CP4 EPSPS Bt transgenic new maize hybrids on insidious flower bugs [Orius insidiosus (Say)] was studied in Nebraska (Mead, C lay Center, and Concord) during 2007 and 2008. The Bt effect was compared to CP4 EPSPS maize (isoline), conventional maize, and insecticide applications of permethrin (Pounce® 1.5G) and bifenthrin (Capture® 2EC) to control first and second generations of Ostrinia nubilalis (Hubner), respectively. Yellow sticky cards, visual observations, and destructive samplings were used to evaluate O. insidiosus abundance. The yellow sticky card data in 2007 showed that O. insidiosus abundance was lower on Pounce® 1.5G treated non-Bt isoline maize plots compared to the BT transgenic hybrid s at 60 and 90 days after planting (DAP). From visual observations, numbers of O. insidiosus were lower in Pounce® 1.5G treated plots and no adverse effects of the Bt hybrids was observed. In 2008, no significant differences were found among treatments in the sticky card data, but the O. insidiosus population significantly increased, with increasing DAP, where the lowest and highest numbers were recorded at 30 and 120 DAP, respectively. In the visual observation and destructive samplings, numbers of O. insidiosus were lower at Concord compared to other sites. Results from the visual observation data in 2008 also revealed that O. insidiosus abundance was lower on Pounce® 1.5G treated plots compared to other treatments. This study showed no adverse effects of the new BT transgenic hybrids that included stacked resistance genes on O. insidiosus compared to the non-Bt maize hybrids.

Morphological and Genetic Analysis of Four Color Morphs of Bean Leaf Beetle

Abstract Bean leaf beetle (BLB), Cerotoma trifurcata (Forster; Coleoptera: Chrysomelidae), exhibits considerable color variation but little is known about the underlying genetic structure and gene flow among color phenotypes. Genetic and morphological variation among four color phenotypes—green with spots (G+S), green without spots (G-S), red with spots (R+S) and red without spots (R-S)—were analyzed using amplified fragment length polymorphisms (AFLP) and morphometrics, respectively. AFLP generated 175 markers that showed ≥80% polymorphism. Analysis of molecular variance (AMOVA) indicated that genetic variation was greatest within phenotypes (82.6–84.0%); gene flow among the four phenotypes was relatively high (Nm = 3.82). The dendrogram and STRUCTURE analysis indicated some population divergence of G-S from the other phenotypes. Morphological parameters were similar among phenotypes except that R+S showed significant differences in weight and body-length. Canonical variables 1 and 2, based on average morphometric characters, accounted for 98% of the total variation; some divergence was indicated between G+S and R+S from each other and from the G-S/R-S BLB color morphs. The pattern of genetic variation indicated potential divergence of G-S and G+S from each other and from R-S and R+S. Although these results indicate that the four different color morphs are not genetically or reproductively isolated, there is some genetic differentiation/structure and morphological dissimilarity suggesting weak/incomplete isolation.

Physiological Effects of Citrus Leafminer Phyllocnistis citrella (Lepidoptera: Gracillariidae) Larval Feeding on Photosynthetic and Gaseous Exchange Rates in Citrus

Abstract Feeding damage by arthropods exposes plants to pathogens and interferes with plant physiological processes. Feeding by the citrus leafminer (CLM), Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae), larva exposes leaf cuticle to the causal pathogens of the citrus canker disease. We investigated the impact of larval feeding on photosynthetic rate (Pn), CO2 exchange rate (Ci), and H2O exchange rate (Wi) in eight citrus cultivars [Citrus mandarins (Kinnow, Seedless Kinnow, Feutrells early), Citrus sinensis (Succari, Salustiana), Citrus tangerines (Fairchild), Citrus limon (China lemon), and Citrus paradisi Macfad (Grapefruit)] under natural conditions in comparison with control plants protected from larval feeding. The effects on gas exchange parameters were tested by allowing the single first instar larvae per leaf to feed till pupation at the rate of three leaves per plant and 10 plants per cultivar. A consistent reduction in leaf Pn, Ci, and Wi rates with larval development through 19 d was observed in all cultivars except Grapefruit in which all three parameters decreased through 13 d and then increased consistently through 19 d. Reductions in Pn, Ci, and Wi were significantly correlated. All three parameters of CLM-infested plants were reduced significantly compared to their levels in control plants except Pn in Kinnow, China lemon, and Grapefruit; Ci in Grapefruit; and Wi in Succari. Pn was reduced most in Fairchild, whereas Ci and Wi were reduced most in China lemon. The consequences of these physiological alterations in regions with high CLM populations could be even more intense and negatively impact plant health, tolerance to pests and diseases, and yield.

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.

Effects of effluent water on the abundance of cowpea insect pests

Botswana experiences low and unreliable rainfall. Thus, the use of effluent water in agriculture is increasingly important. Insect damage is the major constraint for cowpea grain production in the most cowpea-producing lands. We investigated the effects of effluent water on insect pest abundance on cowpea (Vigna unguiculata) under field conditions. The experiment was laid out in a randomized complete block design with 100, 75, 50, and 25% of effluent water and 0% (control—clean tap water) treatments. Treatments with 100% effluent water resulted in a significant increase in insect pest populations as compared with the control. These results show that the use of effluent water to irrigate crops may increase incidence, abundance, and damage caused by insect pests possibly by decreasing plant vigor. The use of effluent water in agriculture should be addressed in a wise way.

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.

Short-horned grasshopper subfamilies feed at different rates on big bluestem and switchgrass cultivars.

Abstract Grasshopper species belonging to subfamilies Melanoplinae, Gomphocerinae and Oedipodinae were tested for their feeding rate on three types of grass. All grasshopper species were offered Shawnee and Kanlow cultivars of switchgrass, Panicum virgatum L. and big bluestem, Andropogon gerardii Vitman. The grasshoppers, Melanoplus femurrubrum and Melanoplus differentialis were also tested for their feeding on turgid or wilted leaves of the Shawnee cultivar of switchgrass. We found that M. differentialis consumed more switchgrass compared to big bluestem while M. femurrubrum and Arphia xanthoptera consumed the most Shawnee switchgrass. The M. differentialis consumed more turgid grass compared to wilted switchgrass. The feeding performances show differences among grasshopper species even in the same subfamily and suggest that Melanoplinae grasshoppers may become destructive pests of switchgrass planted for biofuel production.