Defining the economic threshold determinants for the Asian corn borer,Ostrinia furnacalis(Guenee) in the Philippines

Abstract

The economic threshold determinants for the Asian corn borer, Ostrinia furnacalis (Guenée) were defined over several croppings. The relations between leaf injury, larval equivalents and the corresponding yield losses were established. The larval equivalents did not necessarily follow the increase of the leaf injury rating during the late whorl stage. Leaf damage and the larval equivalents correlated well with yield loss. Using the number of larvae per plant as parameter based on current prices of corn and other inputs, an ETL of not more than one larva/plant was established. The egg mass density, larval population and egg mass frequency indices were positively correlated, especially at their respective peak densities. LIR or leaf damage, number of larvae per plant and the frequency index of egg masses were indicated as good determinants of the ETL, with the egg mass frequency as most practical and convenient for use by farmers.

Estimation of economic injury level ofAphis craccivoraKoch. (Homoptera: Aphididae) infesting faba bean in new reclaimed area

“…and decreased the percentage of infestation (Table 4), i.e. the percentage of infestation could be a good economic threshold level parameter (Morallo-Rejesus et al 1990). …”

Production Risk, Farmer Welfare, and Bt Corn in the Philippines

“…Bt corn in the Philippines was mainly developed to be resistant to the Asian corn borer ( Ostrinia furnacalis Guenee) (see Morallo-Rejesus and Punzalan 2002). The Asian corn borer is one of the most destructive corn pests in the country and typically accounts for 20–30 percent of annual crop damage (Dela Rosa 2001).…”

Baseline Susceptibility of the Field Populations of Ostrinia furnacalis in Indonesia to the Proteins Cry1A.105 and Cry2Ab2 of Bacillus thuringiensis

“…A recent study (2018)(2019) in Lampung and Central Java showed that O. furnacalis infestations were present in as many as 95% of corn plants with an average of four holes per stalk and gallery lengths of 4-6 cm [7]. This level of damage was above the economic threshold for this insect, estimated as one larva (hole) per stalk [8,9]. One O. furnacalis larva boring per plant during V10, R1, or R2 resulted in grain yield losses of 4.94%, 4.56%, or 3.76%, respectively [9].…”