RELATIONSHIP BETWEEN RADICAL INFESTATION OF Hylastinus obscurus (MARSHAM) AND THE YIELD OF CULTIVARS AND EXPERIMENTAL LINES OF RED CLOVER (Trifolium pratense L.)

Abstract

Red clover (Trifolium pratense L.) is a valuable forage legume grown alone or in mixture with grasses in temperate regions of the world. Red clover is adapted to a wide range of soil types, pH levels, environmental and management conditions. However, the main limitation of this species is the lack of persistence related to the high mortality of plants. In Chile the main biotic factor affecting survival of plants is the root borer Hylastinus obscurus (Marsham) (Coleoptera; Scolytidae). In 1989, a red clover (T.

Field response of Hylastinus obscurus Marsham (Coleoptera: Curculionidae) to E-2-hexenal and limonene, two host-derived semiochemicals

“…Our results do not agree with those reported by Alarcón et al (2010), who showed a lower abundance of this curculionid and a higher red clover forage yield for Superqueli INIA and Syn II Pre III. One possible explanation is that the authors of this previous study evaluated the population dynamics of H. obscurus and their potential influence on the selection of new cultivars through agronomic parameters, such as dry matter, plants m -2 and root crown, but did not evaluate the effects of semiochemicals on the curculionid.…”

“…By contrast, limonene repelled the insects, and an increase in the limonene content along with a decrease in the E-2-hexenal content was associated with a loss of attractiveness of the 2.5-yr-old clover roots (Tapia et al, 2007). Alarcón et al (2010) There are many benefits to suggest that semiochemicals (used for behavioral control) are ideal components for use in integrated pest management (IPM) programs, including the following: 1) a low risk to human health and the environment compared with insecticides, 2) long-distance effectiveness because of their high volatility, and 3) usage generally at the same concentrations as those found in nature. For these reasons, studies are needed to provide a more complete understanding of the use of semiochemicals under field conditions for developing behavioral methods to control H. obscurus.…”

Influence of long-chain fatty acids on weight gain of Hylastinus obscurus (Coleoptera: Curculionidae)

“…The number of insects that can infest the roots of red clover is a result of the number of oviposited eggs (Alarcón et al, 2010). Our results suggest that the studied red clover cultivars and the experimental line contain fatty acids in variable proportions with varying degrees of stimulant and deterrent activities.…”

“…The lowest population size of this insect was found in the Superqueli INIA cultivar, which has been categorized as resistant to H. obscurus (Alarcón et al, 2010), and this cultivar also contained the highest content of palmitic acid. Furthermore, insects fed an artificial diet supplemented with the root extract from this cultivar exhibited a greater weight loss.…”

“…Since 1989, a red clover-breeding program has been conducted at the Centro Regional de Investigación Carillanca of the Instituto de Investigaciones Agropecuarias (INIA, Chile), with the main objectives of improving the survival, forage yield and persistence of plants compared to the Chilean diploid and the double-cut cultivar Quiñequeli INIA released in 1962 (Alarcón et al, 2010). Currently, we are investigating the role of plant chemistry in the life cycle of red clover root borer.…”