Survey of aphidiine parasitoid wasps (Hymenoptera: Braconidae: Aphidiinae) associated with citrus aphids, and other aphids (Hemiptera: Sternorrhyncha: Aphididae) common in citrus orchards in Western Puerto Rico.

Abstract

Little information is available on the identity, importance, and abundance of citrus aphid natural enemies in Puerto Rico, especially in the case of hymenopterous wasps. This information is crucial to design research supporting IPM/biological control programs in Puerto Rico citrus orchards. We present a discussion of the data collected from a survey of citrus aphid parasitoid conducted in Western Puerto Rico and around the Island.

The parasitoid complex of citrus aphids on Agricultural Research Extension in Adjuntas and Enseñat Farm collected during this study were comprised of two aphidiine parasitoids: Lysiphlebus testaceipes (Cresson) and Lipolexis oregmae (Gahan). This last is a first record for Puerto Rico. L. oregmae was the most common aphidiine collected. Abundance of L. oregmae and L. testaceipes was greatly different between citrus orchard and among aphid species on each orchard. Percentage of emergence was also different between citrus orhards. There was not significant difference in the parasitism on both aphid species among citrus orchard. In regards of the colonies parasitized, percentage was 16.54%. There was not significant difference in the colonies parasitized on both aphid species among citrus orchard. Parasitoids collected from non-citrus aphid colonies in Western Puerto Rico were Aphidius sp, Diaretiella rapae (McIntosh), L. oregmae Gahan and L. testaceipes (Cresson).

Seasonal abundance of citrus aphid colonies was different between orchards. Enseñat citrus orchard had two mains flushes peacks while there were three in Adjuntas. Statistical analysis indicated that there is not significant difference (P value = 0.7597) in the flush patterns between both sites. Citrus aphid infestation followed the citrus flush pattern in both sites. Positive correlation (R^2= 0.31) between the citrus aphid infestation and the amount of young flushes were obtained in both sites (P value = 0.001). Preference on the structure in the citrus flush was recorded from colonies in both sites. Statistical analysis indicated significant difference (P value < 0.001) on the preference of aphid species to the structure in the citrus flush. Being the foliage preferred for Aphis spiraecola Patch while the twig was preferred for Aphis (Toxoptera) citricidus (Kirkaldy). As a contribution to the knowledge of Aphididae a total of 23 species were identified being Greenidia sp. a first record for Puerto Rico.