As ubiquitous organisms entomopathogenic fungi may natually occur within environment including phylloplanes and soil or deposite and survive for a while after spraying a fungal suspension to control insect pest. The existence of pathogenic fungi is a threat to arthropods foraging for food and oviposition sites. The detection and avoidance of pathogens is important for host survival, longevity and ultimate fitness. Although entomopathogenic fungi are ubiquitous worldwide and act as common natural enemies of many invertebrate species, very few studies have conducted abiut the detection and avoidance of pathogenic fungi by insect pest. We have studied that an insect pest can recognize a high virulence fungi on crop surface, avoid oviposition and don’t enter the field treated their pathogen.
R. pedestris is a major insect pest in agricultural production, especially on soybean and tree fruit, in Korea. Currently, the management of this pest relies mainly on insecticide application in most commodities. However, the chemical controls cause numerous environmental problems. To develop sustainable management tools, it is fundamental to understand the basic biology and ecology of R. pedestris. However, the overwintering ecology of this pest is virtually unknown. In this study, we surveyed diverse landscapes including high elevation mountains soybean fields and there neighboring forests to find and characterize the overwintering sites of R. pedestris. In the field, we sampled leaf litters from 1㎡ grids to locate overwintering R. pedestris. The samples were taken every 100m altitude in the mountain areas or every 50m distance in the flat landscapes. Overwintering R. pedestris were found from 6 samples out of 137 samples. All overwintering R. pedestris were located from forested areas adjacent to urban landscapes in Seong-Nam si, Gyeong-Gi Do. Interestingly, no overwintering R. pedestris was found from in the samples collected from high elivation mountains including Yeon-In, Song-Ni, Chi-Ak, Ga-Ya, Wol-Chul. likewise, no overwintering individual was found from soybean fields and their neighboring forested areas. With caveat that the data were collected only for 1 year, our results support that R. pedestris overwinters solitary resulting in low detection rates from the samples. Given that R. pedestris typically disperse into cultivated crops with high densities, it is important to better understand environmental factors affecting the presence or absence of overwintering R. pedestrris in diverse landscapes. The knowledge would be essential to develop sustainable monitoring and management programs for this economically important pest in Korea.
Amur silver grass, Miscanthus sacchariflorus is one of the promising biofuel crops. A damage of noctuid pest, Leucapamea askoldis was firstly observed from Amur silver grass in Hwasun silver grass plantation during the survey of insect pests of Amur silver grass in Iksan, Hwasun, and Sancheong plantation areas in Korea. The host of L. askoldis was not known yet in Korea. Thus, M. sacchariflorus was the first known host in Korea. The L. askoldis damage was observed as larval feeding on newly grown shoots of M. sacchariflorus close to soil surface from early April to early May in 2013. Investigated larval density was 1.6 ± 1.1 per m2 on April 4 and damage rate of shoots was 0.8% ± 0.4 per hundred plants on May 4, 2013. The larvae bore into shoots of M. sacchariflorus and then feed inside of plant. The damaged shoots are easily pulled out and distinguished by the boring hole on the shoots.
Insect occurrence is closed related to crop and environment. Global climate changes as environment factor influencing not only crops but also insects on their behavior, distribution, development, survival and reproduction. Insect life stage are most often calculated using accumulated degree days from base temperature and biofix point. Temperature is also main factor to changes in moisture humidity and CO2 that effect on crop and insect development. Precipitation is another climate change on consideration factor to insect survival. Therefore, the precise impacts of climate change on insects is somewhat uncertain because it may change favor some insects while others may inhibit their development. On predicting the impact of climate change on insect is very complex exercise and need closed cooperation with experts on modeling. Some generalized predictions can be made, based on current pest distributions and severity of insect outbreaks in individual regions. At the present in Thailand, some alien insect species often present by global trades as by climate change.
In nature, plant diseases, insects and parasites (hereafter called as "pest") must be co-survived. The most common expression of co-survival of a host crop to the pest can be tolerance. With tolerance, chemical uses can be minimized and it protects environment and sustains host productivity and the minimum pest survival. Tolerance can be applicable in all living organisms including crop plants, lifestocks and even human beings. Tolerant system controls pest about 90 to 95% (this pest control system often be called as horizontal or partial resistance), while the use of chemicals or selection of high resistance controls pest 100% (the most expression of this control system is vertical resistance or true resistance). Controlling or eliminating the pests by either chemicals or vertical resistance create new problems in nature and destroy the co-survial balance of pest and host. Controlling pests through tolerance can only permit co-survive of pests and hosts. Tolerance is durable and environmentally-friend. Crop cultivars based on tolerance system are different from those developed by genetically modified organism (GMO) system. The former stabilizes genetic balance of a pest and a host crop in nature while the latter destabilizes the genetic balance due to 100% control. For three decades, the author has implemented the tolerance system in breeding maize cultivars against various pests in both tropical and temperate environments. Parasitic weed Striga species known as the greatest biological problem in agriculture has even been controlled through this system. The final effect of the tolerance can be an integrated genetic pest management (IGPM) without any chemical uses and it makes co-survival of pests in nature.in nature.