Development Of Infestation Research Articles

The effect of an altitudinal gradient on the abundance and phenology of the coffee berry borer (Hypothenemus hampei) (ferreri) (Coleoptera: scolytidae) in the Colombia Andes

Globally, the coffee berry borer (CBB) Hypothenemus hampei (Ferreri) is the most severe pest of the commercial coffee species arabica coffee (Coffea arabica). Heterogenous landscapes characterize many coffee-growing areas. We studied the phenology of coffee and the abundance, and development of infestation by CBB within the context an altitudinal gradient in the coffee-growing region of Caldas, Colombia. This was between 1200 m and 1800 m (a.s.l.) from September 2019 to July 2020 covering two seasons of coffee flowering. Coffee berry phenology did not differ over the altitudinal gradient studied, but CBB abundance and berry infestation differed in quantity and timings, with lower altitudes having higher abundances and proportions of infestation than higher altitudes. In the context of CBB management, October through to December is vital for coffee farms <1500 m as CBB abundance and infestation both spike, and March to June is key for farms between 1500-1700 m for the same reasons. In conclusion, coffee farmers in highly heterogeneous landscapes will have to adjust their CBB management according to the altitude gradients of their farm.

Biospeckle Activity of Highbush Blueberry Fruits Infested by Spotted Wing Drosophila (Drosophila suzukii Matsumura)

In this study, the potential of the biospeckle phenomenon for detecting fruit infestation by Drosophila suzukii was examined. We tested both graphical and analytical approaches to evaluate biospeckle activity of healthy and infested fruits. As a result of testing the qualitative approach, a generalized difference method proved to be better at identifying infested areas than Fujii’s method. Biospeckle activity of healthy fruits was low and increased with infestation development. It was found that the biospeckle activity index calculated from spatial-temporal speckle correlation of THSP was the best discriminant of healthy fruits and fruits in two different stages of infestation development irrespective of window size and pixel selection strategy adopted to create the THSP. Other numerical indicators of biospeckle activity (inertia moment, absolute value of differences, average differences) distinguished only fruits in later stage of infestation. Regular values of differences turned out to be of no use in detecting infested fruits. We found that to provide a good representation of activity it was necessary to use a strategy aimed at random selection of pixels gathered around the global maximum of biospeckle activity localized on the graphical outcome. The potential of biospeckle analysis for identification of highbush blueberry fruits infested by D. suzukii was confirmed.

A study of significant factors affecting the quality of water in the Oskil river (Ukraine)

The study has explored climate shifts in the Kharkiv region and changes in the hydrological indices of the Oskil river in Ukraine. Predictive models were constructed by the Holt­Winters method. The findings show an expected gradual increase in temperature by 1.9 °C – from 7.8 °C to 9.7 °C – in 2020, which can lead to a decrease in precipitation, the runoff volume, and water consumption. It also has a significant adverse impact on the formation of surface water quality and on the development of infestations. Natural and anthropogenic factors that have the most significant effects on the hydrochemical characteristics of the Oskil river were specified by a multivariate correlation and regression analysis. The research findings show that the quality of aquatic sites is most affected by wastewater discharges and an increase in air temperature, which testifies to the need of reducing loads from industrial facilities and utilities. The study takes into account landscape and environmental characteristics of the river basin. We have assessed rationality of using the basin catchment area on the basis of exponents such as tillage, urbanization, the volume of water consumption, forest cover, meadow cover, lake cover, and changes in the hydrological characteristics that influence the development of the intensity of degradation processes. The assessment of the processes of ravine formation, land erodibility, silting and waterlogging of small rivers in the Oskil river basin has shown a significant increase in the intensity of the degradation processes compared to 1990, which requires applying environmental protection measures to improve the situation. The ranking of the small rivers in the Oskil river basin by the index of process development helps prioritize the funding of environmental protection measures.

Development of early infestations by the miteVarroa jacobsoni in honey-bee (Apis mellifera) colonies in cold climates

The development of an infestation by five to eight introduced adult females ofVarroa jacobsoni Oud. in 35 honey-bee (Apis mellifera L.) colonies was monitored for 16 months with no outside source of infestation. Calculations on the size of the mite populations were based on collection of debris, samples of bees and brood, and estimates of number of bees and broodcells during the summer. In the winter, only dead bees and debris were collected. Samples were taken at 3-week intervals. Data indicated that the mite population probably could increase more than 100 times within one summer, and more than ten times between years, in a climate with a brood-rearing period of less than five months. A large variation in mite population increase existed between colonies. The winter mortality of mites that die with the host or drop from the winter cluster has a large influence on the population dynamics of the mite. Data also indicated that the simple method of counting mites in hive debris is a useful parameter for monitoring the population development ofVarroa in colonies with hatching brood.

Insect infestation of stored raw cocoa in Ghana

In Ghana, a considerable part of the main-crop cocoa is stored for six months or more, some up to nine months, and infestation by insects increases during storage. Data are given, obtained chiefly in Ashanti on the 1957–58 main crop.Assessment by sieving the contents of whole bags and counting the numbers of adult insects found (or, in the case of Ephestia cautella (Wlk.), the larvae and pupae also) showed that at the beginning of the main-crop season (September–November), infestation was very light (1–2 insects per bag), but was present in a high proportion of the bags (46–47 per cent, in October). The species present represent those found regularly breeding in cocoa in Ghana, namely, Ephestia cautella (Wlk.), Lasioderma serricorne (F.), Araecerus fasciculatus (Deg.), Tribolium castaneum (Hbst.), Garpophilus dimidiatus (F-), Ahasverus advena (Waltl), Cryptolestes spp., and an unidentified species of Silvanid. After six months' storage, the total count averaged over 100 per bag and comprised chiefly L. serricorne and T. castaneum; larvae of Ephestia were much rarer (less than five per bag), but adults of Ephestia were abundant in the sheds after 2–3 months' storage.Sieving proved a useful technique for obtaining data on infestation, though careful supervision of staff is required to minimise errors. Variation from bag to bag in the same ‘lot’ of cocoa is large, and estimates based on as few as four bags are unreliable.Assessment of insect damage on samples of cocoa beans taken fortnightly by spear-sampling showed an increase from 0·20 per cent, insect-defective beans in November to 1·0–1·9 per cent, in June. Of 21,000 beans examined in April and May, L. serricorne occurred in 0·17 per cent., and 0·6 per cent, contained living insects. Damage by insects affecting more than 2 per cent, of the beans has been very uncommon in Ghana in the past few years. The effect on quality, as assessed by commercial grading and considered financially, is at present slight, as it also is in terms of loss of weight over the whole crop (certainly less than 0·1 per cent.). E. cautella is the most important species economically, because it can infest the premises of cocoa and chocolate manufacturers in importing countries, and spread to finished confectionery. It affects a large portion of the crop in significant numbers.The primary infestation of cocoa before it comes into licensed storage occurs in thousands of small farms and villages, and no one district or type of source is of special importance. Increase of the infestation during storage occurs chiefly as a development of this primary infestation; cross-infestation from outside sources is relatively unimportant.The application of synergised pyrethrin in white oil within storage sheds as a fog, from which a film was deposited on the stacked bags of cocoa, was carried out in many sheds at intervals of 3–4 days, and a comparison made between sprayed and unsprayed sheds, based on data from sieving. Spraying did not substantially reduce the development of infestations of L. serricorne or other beetles, nor was E. cautella controlled to a degree comparable with experience of similar treatment against E. elutella (Hb.) in Britain; this may be due to the fact that E. cautella in Ghana develops in bags throughout the stack, and not chiefly in the peripheral bags, as does E. elutella in Britain.Conditions affecting the film-spraying of bagged cocoa in Ghana differ greatly from those in Britain. Uncontrolled ventilation at the eaves of sheds results in a considerable loss of insecticidal fog, and uneven distribution of deposit; the undersurface of the stacks cannot be sprayed, because they rest on wooden dunnage; it is difficult to maintain an effective oil-film on the topmost horizontal surfaces of the stack, near the roof, of which the temperature frequently exceeds 100°F.; deposits probably do not retain their toxicity for more than a few days.Variations in the materials from which cocoa-storage sheds are constructed, and in their design, cause relatively small differences in internal climatic conditions, and these have even less effect on the temperature of the cocoa in bags, which is generally in the range 82–88°F. The moisture content of the cocoa was about one per cent, less in a hotter type of shed than it was in one of a cooler type, and it is considered that the construction of sheds should aim at producing the hotter, drier conditions that are attainable, in order to keep moisture contents down and restrict the development of moulds, mould-feeding beetles and Araecerus fasciculatus.