Synchronous Occurrences of the Diamondback Moth (Lepidoptera: Plutellidae) and its Parasitoid Wasp Cotesia vestalis (Hymenoptera: Braconidae) in Greenhouses in a Satoyama Area

We characterized the correlation between the occurrences of diamondback moth, Plutella xylostella (L.), larvae and their dominant native parasitoid wasp, Cotesia vestalis (Haliday), in commercial greenhouses in a satoyama area, called Miyama, in Kyoto, Japan. In the three greenhouses used in this study, cruciferous ‘mizuna’ (Brassica rapa var. laciniifolia [Brassicales: Brassicaceae]) crops were grown. Pesticides against diamondback moth were not routinely applied in the greenhouses. We confirmed that populations of diamondback moth and C. vestalis were maintained on the wild crucifer plant Rorippa indica in the surrounding area from March to December. In the greenhouses, we observed several occurrences of diamondback moth larvae that were, in most cases, followed by occurrences of C. vestalis. We found that C. vestalis females were attracted by volatiles emitted from mizuna plants that were lightly infested with second-stadium diamondback moth larvae under laboratory conditions. The synchronous appearance of diamondback moth larvae and C. vestalis could be explained by the latter being attracted by the volatiles emitted from mizuna plants infested by diamondback moth larvae in the greenhouses.

Reproduksi, Fekunditas dan Lama Hidup Tiap Fase Perkembangan Plutella xylostella (Lepidoptera : Ypnomeutidae) pada Beberapa Jenis Tumbuhan Cruciferae

ABSTRACTReproduction, fecundity and period of each growth phase of Plutella xylostella on some species of crucifersPlutella xylostella L. is one of major pests of cabbage (Brassica oleracea). P. xylostella, also known as diamondback moth, is an oligophagous with limited host only a crucifers. The pest often causes damage on the plant in the low to high altitude of the land. It is able to attack cabbage leaf from seedling to harvesting. An alternative controlling method that can be done is by using potential parasitoid, Diadegma semiclausum. Its application can be done using conservation technique through environment modification such as planting ornamental plants as parasitoid food source and alternative host for P. xylostella. The research aimed to find alternative host for P. xylostella. Experiment was conducted at greenhouse of Department Plant Pests and Disease, Faculty of Agriculture, Universitas Padjadjaran. Experiment was carried out by observation method using Randomized Blocked Design consisted of five treatments and four replications. The result demonstrated that Rorippa indica and Cardamine hirsuta were alternative host for P. xylostella. The average number of eggs laid on R. indica and C. hirsuta were 226.75 and 216.25 eggs, respectively. Survival rate of P. xylostella infested on R. indica was 32.50% whereas the survival rate of P. xylostella infested on C. hirsute was 28.75%. It can be concluded that P. xylostella was able to spend its whole life cycle on both plants.Keywords: Crucifers, Fecundity, Growth phase, P. xylostella, ReproductionABSTRAKPlutella xylostella L. merupakan salah satu hama utama kubis (Brassica oleracea). P. xylostella, juga dikenal sebagai Diamondback moth, yang bersifat oligofag dengan inang terbatas hanya pada tanaman kubis-kubisan. Hama ini sering menyebabkan kerusakan tanaman pada dataran rendah dan tinggi. Hama ini dapat menyerang pertanaman kubis pada saat bibit sampai panen. Sebuah metode pengendalian alternatif yang bisa dilakukan adalah dengan menggunakan parasitoid, Diadegma semiclausum. Penerapannya dapat dilakukan dengan menggunakan teknik konservasi melalui modifikasi lingkungan seperti menanam tanaman hias sebagai sumber pakan untuk parasitoid dan inang alternatif untuk P. xylostella. Penelitian ini bertujuan untuk menemukan inang alternative dari P. xylostella. Percobaan dilakukan di rumah kaca Departemen Hama dan Penyakit Tumbuhan, Fakultas Pertanian, Universitas Padjadjaran. Percobaan ini dilakukan dengan metode observasi menggunakan RancanganAcak Kelompok yang terdiri dari 4 perlakuan dengan 4 ulangan. Hasil penelitian menunjukkan bahwa Rorippa indica dan Cardamine hirsuta merupakan inang alternatif bagi P. xylostella. Rata-rata jumlah telur yang diletakan pada R. indica dan C. hirsuta adalah 226, 75 dan 216,25 butir. Kelulusan hidup P.xylostella yang di-infestasikan pada R. indica adalah 32,50% dan pada C. hirsuta adalah 28,75%. serta pada kedua jenis tanaman tersebut, P.xylostella dapat menyelesaikan seluruh siklus hidupnya.Kata Kunci : Cruciferae, Fase perkembangan, Fekunditas, P. xylostella, Reproduksi