Describing a moth’s phenology – a brief introduction/example

The citrus leafminer, Phyllocnistis citrella Stainton (Lepidoptera: Gracellariidae) has been a pest of oranges as well as other citrus crops since its accidental introduction into the United States and Homestead, Florida through young nursery stock (1993). Initially in Broward and Collier counties, the moth quickly spread throughout the state infesting and young shoots (Heppner 1993).
Damage by leafmining leads to reduction in photosynthesis, malformation of leaves, and increases susceptibility to canker (Graham et al. 2004, Gottwald et al. 2007). Growers in the region have expressed deep concern over increases in citrus leafminer (CLM) damage the past 2 years and associated canker spread. Efforts to control the pest with foliar insecticides generally meet with limited success. Therefore it is necessary to find more effective and sustainable means to monitor and control leafminer populations. Such an objective requires studies on better sampling and monitoring procedures. Populations of P. citrella have been confirmed in Southwest Florida, and the current research sought to determine the existence, distribution, and density of P. citrella in six citrus grove locations throughout Collier and Hendry Counties.
Sticky traps baited with pheromone specific for CLM have been used for mating disruption (Stelinski et al. 2008, Lapointe et al. 2009), timing insecticide spraying (Grafton-Cardwell et al. 2008, Jones and Stansly, unpublished data), monitoring distribution (Grafton-Cardwell et al. 2008), tracking adult emergence (Ujiye 2000), and monitoring CLM within citrus groves (Ujiye 2000). The latter is done by dispensing pheromone traps in citrus groves and counting the number of males that arrive at traps on a weekly or bi-monthly basis. In general, pheromone traps are baited with lures that attract males of a specific species by using synthetic compounds that mimic the female sex pheromone. The chemical component of the CLM pheromone was identified as a 30: 10: 1 mixture of (Z, Z, E)-7,11, 13-hexadecatrienal (Z7Z11E13-16Ald), (Z,Z)-7,11-hexadecadienal (Z7Z11-16Ald), and (Z)-7-hexadecenal (Z7-16Ald) (Leal et al. 2006). While control of CLM by mating disruption was successful at low rates (Stelinski et al. 2008), the cost is still prohibitive for many growers ($125g/ac ISCA). Ujiye (2000) used Yamamoto (1971) development data for citrus leafminer to verify the number of generations per year in citrus areas of Japan (Miyazaki, Kochi, and Wakayama), and these models are used to predict optimal spray timing of insecticides (Stelinski 2011).
We tested the use of pheromone traps in citrus groves to improve grower management of CLM. In 2011 and 2012, we conducted trials to monitor flight of CLM under various management practices and determine the number of generations of CLM per year in SW Florida. This paper describes the phenology of CLM in Southwest Florida under 5 management scenarios including an unmanaged block of citrus. We used this information and temperature data to develop a preliminary degree day model for prediction of CLM flight. We provide recommendations for management of CLM and citrus canker disease.



Categories: Monitoring, Phenology

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