Kinds Of Pests Research Articles

The tropical backyard: performing environmental difference

AbstractThis paper extends debates investigating the importance of domestic yards and gardens in shaping identities and the everyday practices and performances of human–nature interaction in a tropical city. It presents findings from a pilot study investigating backyards in a small but ethnically diverse neighbourhood in Cairns, Australia—a site that raises questions about the normative constructions of “nature” in much of the literature. The paper explores how Cairns residents make sense of their backyards, especially in terms of how they relate to them as “tropical”. Living in Cairns means managing excess water during the rainy season, dealing with new kinds of pests, and being critically conscious of the temperate bias of Australian garden retailers and house/garden magazines. The paper frames these experiences within a longer tradition of tropicality or a (western) way of making sense of/imagining tropical regions and environmental difference. In so doing, it opens up a new cultural geography of the suburbs, displaces normative constructions of “nature” and shows how the legacies of European colonialism still play out in a dominant Australian culture.

Biodegradation of pesticides using density-based clustering on cotton crop affected by Xanthomonas malvacearum

In today’s world, cotton is the most vital non-food agrarian commodity. During its growth, it is prone to various kinds of pests and bacteria which causes many diseases. And to save the cotton crop from bacteria and pests, various harmful chemicals in the form of pesticides are used. Over the years, due to the extensive use of pesticides, their interaction with the biological system in the environment has caused many problems. After analyzing the harmful effects of pesticides, it is essential to remove these harmful chemicals from the environment to plant the other seasonal crops. To accommodate this constraint, this paper proposes a method to efficiently use pesticides on the cotton crop which is affected by Xanthomonas malvacearum and how to biodegrade the pesticides from the soil where it was grown. To rectify this instance, we use a methodology named density-based clustering for finding the areas of the cotton plant that were affected by Xanthomonas malvacearum. On the other hand, the same algorithm is used to identify the areas in the soil that were highly affected by pesticides. By identifying the affected areas in the field, the methods such as biostimulations, bioventing, bioaugmentation, and other related techniques can be applied to degrade the levels of pesticides. It can be incurred from experimental results that the density-based method outperforms in identifying the pesticide-affected areas which will help the farmers to make the crop production effectively.

Growth-inhibitory activity of phenolic compounds applied in an emulsifiable concentrate - ferulic acid as a natural pesticide against Botrytis cinerea

Phenolic compounds are part of the protection system of plants against all kinds of pests and are therefore considered a natural alternative to conventional plant protection agents. Five phenolic compounds (phlorizin, resveratrol, ferulic acid, 5-n-alkylresorcinols, and quercetin) were used as active ingredients in the preparation of a bioactive emulsion and screened for their ability to inhibit the growth of four phytopathogenic fungi - Aspergillus niger, Botrytis cinerea, Penicillium expansum, and Fusarium culmorum. By using design of experiments, several interactions between the phenols were determined, however, ferulic acid was identified as highly effective against the growth of Botrytis cinerea. The growth-inhibitory effect of this emulsion was enhanced by adapting the ferulic acid concentration (0.085%, m/v) with the help of response surface methodology. Subsequent tests confirmed the activity against the growth of nine fungicide-resistant Botrytis cinerea isolates and showed promising results against the infection of injured and contaminated grapes.

Does gall midge larvae cause pre-dispersal seed mortality and limit cornflower population growth?

Many kinds of pests can reduce seed production. Some directly attack seeds before they are released, and some are hosted by the fruit and impact seed ripening and viability indirectly. Pre-dispersal seed mortality may have strong effects on plant population dynamics and evolution. Our goals were to determine to what extent insect-mediated pre-dispersal seed mortality contributes to population-level declines of cornflower, Centaurea cyanus L. We recorded occurrence and abundance of seed-feeding insects on flower heads in twelve cornflower populations. We measured flower head size, number of disc florets, seed production, and seed viability and germination. Larger flower heads had proportionally fewer healthy seeds. Although we observed no visible damage to the C. cyanus seed, the presence of gall midge (Cecidomyiidae) larvae inside the flower head correlated with four times fewer viable seeds. It seems that gall midges could have a significant impact on ovule fertilization, seed abortion and viability of fully developed cornflower seeds. The higher rate of aborted seeds in the presence of gall midge larvae could have been because the larvae extracted resources from the seeds, or because the larvae repelled pollinators. The viability of apparently healthy seeds was 40% lower in flower heads that contained larvae and/or aborted seed. Insect-mediated pre-dispersal mortality could select against evolution toward larger flower head, and have detrimental consequences on seed number, viability and germination, all of which could limit the spread of C. cyanus populations.

Side-effect of acetamiprid in adult Africanized honeybee

The insecticide acetamiprid is widely used in many crops in Brazil like cotton, beans, citrus and rice to control many kind of pests and ensure high yields. Honeybees (Apis mellifera) may frequently become exposed to such chemicals as a consequence of their foraging activities (collecting water, natural resins, pollen and nectar) or even by spray drift, since in some of these cultures this neoniconinoid is applied by aircraft. Intoxication resulting from exposure to xenobiotics products can be lethal, which is easily identifiable, or cause effects on the physiology and insect behavior. These effects, caused by sublethal doses are difficult to measure (such as paralysis, disorientation or behavioral changes), and can compromise the entire social structure of the colony. To improve the knowledge about the action of low doses of insecticides in honey bees, the effects of acetamiprid was studied in adult Africanized honey bees. To achieve this goal was used two behavioral protocols: proboscis extension reflex (PER) and locomotor activity. Bees were obtained from adequately fed, healthy and queen-right colonies. Adult worker bees were collected from frames without brood. After insecticide application, the bees were kept in plastic containers (250 mL) and held in a incubator at a temperature of 32°C and relative humidity around 70% and were fed with cândi solution. Initially, LD50 and LT50 were estimated. The PER and locomotor activity were analyzed 1, 4 and 24 hours after topical application of 1μl in doses corresponding to LD50, LD50/10 and LD50/100. The PER was impaired 1 and 4 hours after application of LD50 and LD50/10. The locomotor activity behaviour was impaired 1 hour after application of LD50 and 4 hours after application of LD50 and LD50/10. It was not observed impairment 24 hours after topical application. The greater impairment was found when the behavioral analyses were made close to the period determined by LT50. These results can be justified, probably, due to the presence of a detoxification mechanism. Some studies show that metabolites of acetamiprid were not toxic to honeybee which is compatible with the time of action of the insecticide observed in this study.

Effect of temperature on the development of the mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae)

An invasive mealybug Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) has attacked cotton (Gossypium hirsutum L.) seriously in Pakistan and India, and caused great loss in the production of cotton in recent years. This kind of pests can probably spread rapidly and would threaten cotton and other crops in many infested and non-infested countries. P. solenopsis has first been reported to severely damage Chinese hibiscus (Hibiscus rosa-sinensis) in Guangzhou, in December, 2008. In order to understand the effects of temperature on the development of P.solenopsis, the developmental threshold temperature (Ct) and effective accumulated temperature (K) were calculated for each developmental stage. A total of 30 P. solenopsis individuals were divided into 6 groups and reared at six constant temperatures (18, 21, 24, 27, 30, and 33°C). Total developmental duration ranged from 81.3 days at 18°C to 24.06 days at 30°C for female mealybug, and from 44.21 days at 18°C to 12.95 days at 30°C for male mealybug. Degree-day values for each developmental stage for both male and female mealybugs were determined. Total degree-day values required for full development for female and males were 414.9 and 218 degree-days respectively. Estimated threshold temperatures for different life stages ranged from 12.8°C (pre-oviposition) to11.7°C (3rd instar) for female mealybugs, and 16.5°C (prepupa) to 11.5°C (2nd instar) for male mealybugs. Key words: Mealybug, Phenacoccus solenopsis, development, temperature.

Mathematical Modeling of Occurrence and Population Density of Predatory Spider and Their Preys on Cotton Plants and Broad Bean in Two Governorates in Egypt

The research presents a mathematical simulation of three kinds of pests and their predator for two plants: Cotton and broad bean. The study was applied in two regions in Egypt representing Upper Egypt and Delta. The study is based on similar field experimental results during the two successive years 2003-2004, 2004-2005 in Qaha station- Qalubia governorate and seds station–Beni sweif governorate. Four models are introduced according to the plant and the geographical regions. The data were fitted to continuous curves to enable the process of predicting the number of each kind of the involved species. Many functions are suggested to describe the effect of temperature and relative humidity on population. However, for particular plant in particular area, only narrow ranges occur for both temperature and humidity. A process of smoothing the data was necessary to avoid the very extreme points of sudden increase (due to migration or eggs hatching) which can not be taken into account in a mathematical model. After smoothing the data, a least square method was used to fit the points to continuous curves. Then an algorithm has been made aiming to predict the number of the preys and predator at any time by knowing the initial state of each of them. The modeling for anticipating the expected number of spiders and preys for the different months was achieved using a Microsoft Visual Studio program. Four models are constructed and they have been shown to be easy for users. A calibration for the model was examined using a comparison study between field and model results, and a reasonable matching was observed.