@article{Cortaga_2023, title={SOURCES OF RESISTANCE AND TRICHOME ANALYSIS OF PHILIPPINE INDIGENOUS Hoya SPECIES AGAINST THE MILKWEED APHID, Aphis nerii Boyer De Fonscolombe (HEMIPTERA: APHIDIDAE)}, volume={30}, url={https://journal.biotrop.org/index.php/biotropia/article/view/1783}, DOI={10.11598/btb.2023.30.1.1783}, abstractNote={<p>The Philippines is one of the centers of diversity of <em>Hoya </em>and an extensive collection of indigenous species are conserved at the Institute of Plant Breeding, University of the Philippines Los Baños. In maintaining these <em>Hoya</em> species inside the screenhouse, the major insect pest noted to attack the plants is the milkweed aphid, <em>Aphis nerii </em>Boyer de Fonscolombe. Thus, Hoyas were evaluated for resistance against this insect pest. Among the 45 <em>Hoya</em> species evaluated, 11 showed promising results wherein no aphid infestation was consistently observed during the three evaluation trials. These are <em>H. aurigueana</em>, <em>H. carnosa</em>, <em>H. coriacea</em>, <em>H. diversifolia</em>, <em>H. greenii</em>, <em>H. imperialis</em>, <em>H. madulidii</em>, <em>H. obscura</em>, <em>H. odorata</em>, <em>H. paziae</em>, and <em>H. pubicalyx</em>. As the first line of plants defense against herbivory, we sampled four resistant (<em>H. madulidii</em>, <em>H. pubicalyx</em>, <em>H. carnosa</em>, and <em>H. obscura</em>) and two susceptible (<em>H. buotii </em>and <em>H. meliflua</em>) species for analysis of their trichome traits. The mean trichome length was longest in <em>H. carnosa</em> (0.38mm), followed by <em>H. madulidii</em> (0.33mm), and lastly, <em>H.  pubicalyx </em>and <em>H. obscura </em>(0.15mm). Mean trichome density (at 1.64mm<sup>2</sup> microscopic field) was highest in <em>H. madulidii</em> (54.45), followed by <em>H. pubicalyx</em> (7.5), and lastly, <em>H. carnosa</em> (3.55) and <em>H. obscura</em> (3.45). In contrast, no trichome was observed in the susceptible species <em>H. buotii</em> and <em>H. meliflua</em>. Hence, trichomes are one of the important resistance traits of <em>Hoya </em>against the milkweed aphid. To our knowledge, this is the first report on resistance evaluation in <em>Hoya</em> and the role of its trichomes against the milkweed aphid. The results of this study can aide in the management of milkweed aphids and in developing improved <em>Hoya</em> cultivars with resistance to insects such as milkweed aphids.</p>}, number={1}, journal={BIOTROPIA}, author={Cortaga, Cris}, year={2023}, month={Apr.}, pages={74–81} }