Effects of delayed mating and access to water on oviposition and longevity in navel orangeworm females

Authors: Burks, Charles - Chuck

Submitted to: International Journal of Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/28/2014
Publication Date: 12/8/2014
Citation: Burks, C.S. 2014. Effects of delayed mating and access to water on oviposition and longevity in navel orangeworm females. International Journal of Insect Science. 6:89-98.

Interpretive Summary: The navel orangeworm is a key pest of high-valued irrigated nut crops grown primarily in arid regions. A study was conducted to examine the potential impact of delayed mating and access to water on reproduction of the non-feeding adult stage. Median adult life at temperatures representative of June in Central California was 14-17 days. Over 85% of eggs were laid within the first 6 days after mating, and over 95% within the first 10 days. A 6-day delay in mating reduced reproduction by 55% in females with free access to water, and by 90% in those with no access to water. This 6-day delay reduced the egg-laying period by 50% in both females with access to water and those with none. These results complement field data, quantifying for scientist and growers the impact of mating disruption on the abundance of damaging larvae in this species. They also promote efficient irrigation.

Technical Abstract: A study of delayed mating in the navel orangeworm, Amyelois transitella (Walker) (Lepidoptera: Pyralidae) was conducted to provide information about the potential impact of mating disruption treatments on this key pest of California tree nut crops. Fecundity, fertility, longevity, and ovipositional the reproduction of the non-feeding adult stage period were compared between females mated 1 and 7 d post-eclosion, either with access to water ad libitum from eclosion or with no access to water as adults. Access to water had no effect on total fertility of females mated 1 d post eclosion. In comparison to females mated 1 d post eclosion with access to water, females mated 7 d post-eclosion had a 55% reduction in total fertility with access to water but a 90% decrease without access to water. Water deprivation significantly decreased longevity but not ovipositional period, whereas the converse was true of delayed mating. In all cases, median female survivorship after mating was greater than the time in which 90% of fertile eggs were laid. These findings are discussed with respect to the field ecology of this species, and the impact of mating disruption.