Population Structure Dynamics and Control Countermeasures of Sugarcane Borers in Yunnan Sugarcane Area

To control sugarcane borers scientifically and effectively, the species, population structure and dynamics of sugarcane borers in Yunnan sugarcane areas were analyzed, based on the historical data and survey research. The distribution area and damage of the major sugarcane borers in Yunnan sugarcane areas were ascertained, and the factors influencing population structure dynamics of sugarcane borers and their rampant causes were revealed. According to the damaging characteristics of sugarcane borers, suitable control countermeasures were proposed, including establish-ing and improving sugarcane quarantine system, enhancing quarantine of imported varieties/clones, investigating new sugarcane borer populations thoroughly and systematically, establishing early warning and monitoring system, actively carrying out physical and biological control, and enhancing protection of natural enemies. These countermeasures could help to effectively control sugarcane borers and reduce the damage caused by these borers.

The Occurrence,Damage and Control Strategies of Sugarcane Borers in Yunnan

Sugarcane borers are the most common pests in Yunnan sugarcane areas,and their harm is the most serious presently. The damage caused by sugarcane borers has become the first important factor seriously influencing the sustainable and stable development of sugar industry in Yunnan. To scientifically and effectively prevent and control sugarcane borers to ensure the production safety of sugarcane,the characteristics of occurrence and damage of sugarcane borers in Yunnan sugarcane areas were systematically introduced,and corresponding comprehensive control measures and strategies were proposed according to the characteristics of its occurrence and damage and the actual production of sugarcane.

Detecting sugarcane borer diseases using support vector machine

Based on the fact that great labor of artificial selection was needed after the sugarcane seeds were cut by the sugarcane cutting machine,and there was a misjudgment of the sugarcane borer diseases.SVM(support vector machine)method was proposed in this study to detect the sugarcane borer diseases.With the machine vision technology,together with threshold segmentation,filling and corrosion operation to process the three images of the same sugarcane whose interval is 120
.The classification features,minimum average gray value and the corresponding minimum gray value were selected by adaptive threshold segmentation algorithm,and removed the region which area of 1.The study used radial basis function as the kernel function of SVM,and roughly selected the range of regularization parameters of C and kernel function parameter r.Finally,it selected the optimal parameters by the grid search and the cross validation method to identify sugarcane with diseases.The test showed that correct rate of diseases and disease-free sugarcane is 96%,95.83%for the test set,so the method can effectively complete the sugarcane borer diseases detection.

Responses of Rice Mini-Core Collection Accessions to Damage by Diatraea saccharalis(Fabricius)Stem Borer

This study aimed to observe the response of 32 rice accessions to attack of sugarcane borer (Diatraea saccharalis Fabr., 1794). Twenty larvae were placed on the leaf sheaths of rice plants. At 30 days after infestation, the rice plants were cut at ground level and taken to the laboratory to analyse the signs of borer attack, external and internal diameter of the stem and weight of surviving larvae. The results of the morphological traits of the rice plant, response of the plant to insect attack and development of the sugarcane borer larvae indicated a genotypic variation. The accessions that most favored larval survivals were IRAT 124 and MEARIN. Larvae with highest weight (0.0643 g) were found in IAPAR L 99-98 and the largest internal diameters of the rice stem (5.65 mm) were found in LAC 12. These accessions (IRAT 124, MEARIN, IAPAR L 99-98 and LAC 12) remained morphologically grouped with IAC 47, cultivar susceptible to sugarcane borer. The most tolerant materials based on the ability to produce new tillers after larval infestation were BR IRGA 417 and MTU 15. The results of this study indicate that all the morphological traits were able to separate the accessions of rice into different groups in relation to resistance to the sugarcane borer D. saccharalis. These materials can be used as donor sources in pre-breeding for genetic resistance to sugarcane borers.

Infestation of Diatraea saccharalis(Fabr.)during Five Consecutive Cycles of Sugarcane Crop Succeeding Leguminous Crops

The area cultivated with sugarcane in Brazil is expanding, and increasingly using legumes cover crop in new deployed areas and in those which were reformed. Long-term trials were carried out in Piracicaba, Sao Paulo, Brazil, to evaluate the effect of leguminous green manure on the natural infestation of Diatraea saccharalis (Fabr.) during five cropping cycles of sugarcane “IAC 87-3396”. This study was carried out from October 1999 to October 2005 in Piracicaba, Sao Paulo, Brazil, at coordinates 22°42''S and 47°38''W, 560 m above sea level, in soil classified as Typic Paleudult. Green manure crops were assigned to five treatments: peanuts (Arachis hypogaea L.) (cultivar “IAC-Tatu” and “IAC-Caiapó”), sunn hemp (Crotalaria juncea L.) (cultivar “IAC 1”) and velvet-bean [Mucuna aterrima (Piper & Tracy) Holland] (cultivar “common”). A treatment without any green manure or weed was used as the control. The previous sugarcane crop was destroyed and the soil was prepared in a conventional way (using plow and harrow) before the leguminous crops were sowed. Thirty days after the sowing, weeds were removed and, 120 days later, the crops were cut and its biomass was deposited on the soil surface without incorporation. Experimental plots comprised five rows of sugarcane, each one measuring 10 m long and spaced 1.40 m apart. The sugarcane was harvested 18 months after biomass deposit, on October 25th, 2001 and its stalks were collected at intervals of approximately 12 months in: 07/09/2002, 08/01/2003, 11/07/2004 and 10/06/2005. At harvest, the masses were determined from a sample of sugarcane, cut from three rows (2 m long) in the center of the plot. The losses caused by the sugarcane borer were estimated by the intensity of the infestation by randomly observing and collecting sugarcane stems from each plot. A great reduction in the number of stalks and in the yield was noted proportionally to the intensity of the infestation of the borer in the sugarcane crop grown after the velvet-bean. The sugarcane-velvet-bean rotation should be regarded considering the intensity of sugarcane borer infestation. No influence of the other green manure crops was observed on the intensity of the infestations. However, the harvest seasons of the sugarcane seemed to influence the borer infestation.

Euborellia annulipes Mortality and Predation on Diatraea saccharalis Eggs after Application of Chemical and Biological Insecticides

Chemical and biological insecticides have been frequently used in sugarcane fields to control insects-pests, including the sugarcane borer, Diatraea saccharalis. Among the products used, those based on chlorantraniliprole and Metarhizium anisopliae entomopathogenic fungus, stand out. Euborellia annulipes is an insect of the order Dermaptera considered a potential predator of sugarcane borer eggs. This study aimed to evaluate the direct and indirect effects of the bioinsecticide based on M. anisopliae (Metarril®) and the chemical insecticide chlorantraniliprole (Altacor®) on the mortality of E. annulipes nymphs and adults, the predation and feeding preference of earwigs in eggs treated with the formulated products. Predator mortality was evaluated for seven days after treatment, while the effect on predation was analyzed by preference tests with and without choice, using prey eggs. The products tested were selective to the predator, causing ≤ 2% mortality and not affecting predation. The application of M. anisopliae on sugarcane borer eggs favored the food preference of fourth-instar nymphs, males, and females of the predator. Our results show that Metarril® and Altacor® can be used to control D. saccharalis when associated with the predator E. annulipes.