Submitted to: Caribbean Food Crops Society Proceedings
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/20/2005
Publication Date: 7/1/2006
Citation: Pena, G.E., Goenaga, R.J., Castillo, J., Hodges, G., Evans, G.D. 2006. Steps toward managing the armored scale andaspis punicae in Litchi in Florida and Puerto Rico. Caribbean Food Crops Society Proceedings. Vol(41):138-148. Interpretive Summary: Hard scales generally infest twigs of litchi (Litchi chinensis), and if allowed to multiply, the vitality of young trees may be reduced and branch terminals killed. The hard scale Andaspis punicae was detected in 1993 for the first time invading litchi groves in Florida and in 2004 in Puerto Rico. This study showed that the scale is associated with symptoms known as “corky bark.” Affected trees with this disease, presumably caused by a species of the fungus Fusarium, have irregular patches of raised, cracked, and rough bark, which is friable. Branches die, and eventually so does the whole canopy. Our study showed that the parasitoid wasp, Encarsia lounsburyi, resulted in levels of parasitism ranging between 2.9 and 26.1% in Florida and much higher (40%) in Puerto Rico, thus, providing some control. Various pesticides (Knack, Applaud 2X, Provedo and Novaluron) also provided significant control of the scale but application costs are high. This study provides recommendations on integrated pest management practices to control Andaspis punicae in litchi orchards which can be implemented by growers.
Technical Abstract: The exotic scale Andaspis punicae (Homoptera: Diaspididae) was detected in 1993 in Florida invading litchi (Litchi chinensis) groves causing dieback of branches, and reducing tree vigor and eventually killing trees. During 2004 it was detected in Puerto Rico affecting litchis. The scale has also been associated with symptoms known as ‘corky bark’ in Florida. Here we present results of studies on scale biology, chemical control, efforts toward biological control with parasitoids and preliminary results of the possible association between the scale and the causal agent of ‘corky bark’. On- going studies on scale biology demonstrated that the life cycle of the scales is longer than 60 days before the female scale produces a new generation. Therefore, under south Florida conditions, we may expect 5-6 generations/year. In Florida, levels of parasitism by the native parasitoid Encarsia lounsburyi (Hymenoptera: Aphelinidae) ranged between 2.9 and 26.1 percent of parasitized scales while in Puerto Rico levels of parasitism fluctuated around 40% The chemicals, Knack, Applaud 2x, Provado and Novaluron provided significant scale control 50 days after their application, but their use is restricted by application costs. Effect of a fungicide and an insecticide on scale development and symptoms of corky bark were studied during 2004. Results of an on-going research on the introduction of exotic parasitoids from the South Pacific into Florida for effective biological control of the scale are discussed.