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United States Department of Agriculture

Agricultural Research Service

Title: Variable development rate and survival of navel orangeworm (Amyelois transitella, Lepidoptera: Pyralidae) on pistachios

Authors
item Siegel, Joel
item Kuenen, Lodewyk

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 1, 2010
Publication Date: June 1, 2011
Citation: Siegel, J.P., Kuenen, L.P. 2011. Variable development rate and survival of navel orangeworm (Amyelois transitella, Lepidoptera: Pyralidae) on pistachios. Journal of Economic Entomology. 104(2):532-539.

Interpretive Summary: The navel orangeworm (NOW) is the main pest of pistachios in California but its rate of development in pistachios is unknown. A series of laboratory studies were conducted on different stages of field-collected and processed pistachios to calculate the length of development and survival. The navel orangeworm developed the fastest on new crop pistachios and developed the slowest on unharvested (mummy) pistachios. Development on new crop nuts could be as fast as 13 days in the field, and as longer than 120 days on mummy nuts. The survival of NOW was dependent on nut size and nut maturity and was highest on early split pistachios and lowest on mummy nuts collected in May. These findings indicate that there are multiple, overlapping generations of navel orangeworm throughout the year and that the quality of the nut plays a role in both the rate of development and survival.

Technical Abstract: The navel orangeworm (NOW) is the main pest of pistachios in California but its rate of development in pistachios is unknown. A series of laboratory studies were conducted on different stages of field-collected and processed pistachios to calculate the length of development and survival. The navel orangeworm developed the fastest on new crop pistachios, as fast as 13 days, and developed the slowest on unharvested (mummy) pistachios (longer than 120 days). The average development rate on mature pistachios ranged from 620 to 900 degree-days (DD), and on mummies the average rate was 1,840 DD. There was considerable variation in development rate on all stages of nuts and the interval between the first adult and last adult to emerge was as great as 1,750 DD. These rates are much shorter than the development rate reported for almonds. The survival of NOW was dependent on nut size and nut maturity and was highest on early split pistachios and lowest on mummy nuts. There are multiple, overlapping generations of navel orangeworm throughout the year and the quality of the nut plays a role in both the rate of development and survival. Studies of NOW development rate and survival should be included in the series of tests used to evaluate new varieties of pistachio, because if the NOW develops even faster or has enhanced survival, this must be factored into the management decisions required for the new variety and may possibly impact the management of the existing pistachio plantings.

Last Modified: 9/21/2014
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