Assessment of Infestation Severity by Scale Insects and Citrus Leafminer and Evaluation of Cultivar Susceptibility in a Citrus Orchard in Qasr Ben Ghashir, Libya

Abstract

Scale insects and the citrus leafminer are among the major pests affecting citrus productivity and fruit quality in Mediterranean environments, including Libya. This study aimed to evaluate the infestation severity of three scale insect species: California red scale (Aonidiella aurantii), black scale (Chrysomphalus ficus), and purple scale (Lepidosaphes beckii), in addition to the citrus leafminer (Phyllocnistis citrella), on six citrus cultivars (Fresh Lime, Kenyan local, Java, Lime, Kenyan American, and Abu Surra).

The study was conducted in an orchard located in Qasr Ben Ghashir (Jefara Plain). Samples were randomly collected by examining 100 leaves and 25 fruits per cultivar from five trees. Infestation percentages were calculated for leaves and fruits.

The results showed clear variation among cultivars in infestation levels. The Kenyan local and Fresh Lime cultivars recorded the highest infestation percentages with California red scale (36.8% and 36.6%, respectively), while Abu Surra exhibited complete resistance. The highest citrus leafminer infestation was recorded on Lime and Fresh Lime cultivars (48%).

These results reflect genetic differences in cultivar susceptibility and support the use of less susceptible cultivars within integrated pest management programs to reduce reliance on chemical pesticides.