Threshold Temperatures and Thermal Requirements for the Development of the Olive Leaf Moth; Palpita unionalis Hbn. (Lepidoptera: Pyralidae)

Document Type : Original Article


1 Plant Protection Research Institute, Agricultural Research Center, Dokki, Giza, Egypt.

2 Plant Protection Department, Desert Research Center, El Matariya, Cairo, Egypt.


Olive leaf moth, Palpita
(Hubner) (Lepidoptera: Pyralidae) is one of the dangerous pests
attacking sapling olive trees and nurseries, tender shoots and ripening fruits
inducing economic losses. Accordingly, great efforts were dedicated to reduce
its infestation. The current study aimed to calculate temperature thresholds (t0)
and accumulated heat units (dd’s) for each stage of this pest as a primary step
for developing a forecasting system that will help to define the most precise
time for different control programs. The insect was reared under three
constant temperatures (17, 22 and 27°C each ± 1°C). The time required for
development through egg, larva, pupa and pre-ovipostion increased at lower
temperatures. The lower thresholds of development (t0) were 8.39,
11.46, 13.38 and 12.70°C for eggs, larvae, pupae and pre-oviposition period,
respectively. The average accumulated heat units required for their development
were 61.07, 238.81, 113.68 and 38.17 degree-days. On the other hand, the lower
threshold of development (t0) to complete a generation was 12.04°C
and the average accumulated heat units required for its development was 443.07