No abstract

Aspects of the ecology of Neiara viridula were studied in soybean-growing areas of southeastern Queensland, Australia. Trends in population density, the number of generations, and the sequence of host plants used were investigated. Two principal generations were completed in a season, as shown by a bimodal occurrence of egg masses, nymphs and reproductively immature adult females. Nymphs were numerous relative to adults during two periods, once between late spring and early summer (mainly on wild crucifers: Rapistrum rugosum (L.) All. and Raphanus raphanrsfnon L.) and again in early autumn (on pod-filling soybean). This pattern was consistent across study sites. Between midsummer and late summer, population densities were extremely low and most bugs were in the adult stage. The adult bugs were found on several host plant species, including Medicago sativa L., Daturii @ox L., D. stromonium L., Ricinus coinrnunis L., Zea mays L., Sorghum bicolor (L.) Moench, Macropiilium laihyroides (L.) Urb. and Physalis virginiana L. Possible explanations for the low number of generations completed during the 8 months that the bugs were not in diapause and for low bug numbers during the summer months are evaluated. We suggest that host plant availabilit) and suitability were the major factors contributing to the observed patterns in the population dynamics of N . viridula and that egg parasitism was not important.

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Bacterial apical necrosis is a critical disease in the main production area of mango in Europe. It is caused by Pseudomonas syringae pv. syringae, and produces necrotic lesions on mango buds and leaves, causing severe yield losses due to a decrease of flowering and fruit set. A field study to evaluate control treatments against bacterial apical necrosis was carried out during three seasons on mango trees cv. Tommy Atkins in Huelva (Spain). Experimental treatments included Bordeaux mixture, fosetyl-Al, acibenzolar-S-methyl, gibberelic acid, silicon gel, a mixture between acibenzolar-S-methyl and Bordeaux mixture, and combined applications of fosetyl-Al with Bordeaux mixture or silicon gel. The treatments which caused a consistent reduction in bacterial apical necrosis symptoms at similar levels to the conventional treatment with Bordeaux mixture, were the plant resistance activator acibenzolar-S-methyl and the phosphonate derivative fosetyl-Al applied singly or in combination with other compounds, which could be alternative treatments. These treatments showed a significant decrease in the necrotic buds and/or leaves numbers; however, minor differences in P. syringae-like population levels were observed. The analysis of the inhibitory and bactericidal concentrations of cupric compounds against P. syringae strains isolated from mango tissues suggests that the commercial copper-based treatments with Bordeaux mixture used in the management of mango crops do not work in a bactericidal mode of action.

Effects of temperature and host plant condition on insect development have been examined in a number of studies but their combined effect is not well investigated. In this study the effects of varying temperatures and host plant conditions and its interaction on development, survival, and coloration of solitarious and gregarious forms of African armyworm (AW), Spodoptera exempta, an outbreak pest species, were studied under laboratory condition. Rearing temperature was found to have significant effects on larval and pupal development and pupal weight in both solitarious and gregarious forms. The effects of host plant condition in both forms were variable; significant effects were consistently observed in pupal development for both gregarious and solitarious forms but not in larval development and pupal weight. Larval and pupal survival of the solitarious form significantly decreased with the decreased in temperature, while only pupal survival decreased with the decreased in temperature in gregarious form. Distinct larval coloration was also observed in different temperatures. Larvae reared at high temperature exhibited lighter coloration, while larvae reared at low temperature exhibited darker coloration regardless of rearing density. The significant interaction of temperature and host plant condition on many aspects of insect fitness measured in this study highlights the need for further studies on the effects of other environmental factors such as relative humidity, rainfall, and light intensity to improve predictions as to how these insect pests will respond to climate change.

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The research objective was to quantify the development and survivorship rate of S. dorsalis in different phenological stages of mango and selected weeds. The research was conducted in the laboratory of PT. Trigatra Rajasa, Mango plantation in Ketowan, Arjasa, Situbondo, East Java, Indonesia from February to September 2015. The development and survivorship rate were done through observation of life span of S. dorsalis from egg to pupa. Analysis of Variance and Duncan Multiple Range Test (p = 0.05) with 5 replications were applied to ensure the significant differences among the treatments. The result showed that development and survivorship of Scirtothrips dorsalis were supported by mango flushes and flower as well as some weeds such as Leucania leucochepala, Ipomoea triloba, Achalypha indica, Desmanthus leptophyllus and Azadirachta indica as source of food. Achalypha indica was the most suitable host with development time (12.82 ± 0.21 days) and survivorship (33 %). Weed Tridax procumbent, Momordica charantia and Mimosa pudica were unable to provide the living requirement for immature developmental stage of S. dorsalis.

Using nine microsatellite loci, the genetic diversity of natural populations of Bactrocera occipitalis and B. philippinensis was investigated. Estimates of genetic diversity based on allele number (n a and n e ), heterozygosity (H o and H e ) and Shannon information index (I) revealed that the Cavite population was the most genetically diverse (n a = 18.56; n e = 12.88; H o = 0.58; H e = 0.89; I = 2.55) and Pangasinan was the least (n a = 7.89; n e = 8.94; H o = 0.34; H e = 0.87; I = 2.31). Among groups, the intermediates were the most genetically diverse (n a = 25.44; n e = 15.30; H o = 0.52; H e = 0.92; I = 2.85) and B. philippinensis was the least (n a = 17.44; H o = 0.44; H e = 0.90; I = 2.54). A low level of genetic diversity was detected among populations. Pangasinan and Palawan populations were the most related while Palawan and Guimaras populations were the least. Among groups, B. occipitalis and intermediates were the most related while B. occipitalis and B. philippinesis were the least. Dendrogram analysis indicated that B. occipitalis, B. philippinensis, and intermediates are not genetically distinct from each other.