Spectral sensing of aphid (Hemiptera: Aphididae) density using field spectrometry and radiometry

The greenbug, Schizaphis graminum (Rondani), and bird cherry-oat aphid, Rhopalosiphum padi L., are aphid pests of wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), sorghum (Sorghum bicolor L.), oat (Avena sativa L.), and other cereals worldwide. Greenbug and bird cherry-oat aphid infestation in crops is unpredictable over space and time. From these 2 aphids, greenbug infestation causes significant reduction in yield, and consequently large amounts of insecticides are used to control greenbug populations. Therefore, a repeatable and rapid method is necessary for monitoring aphid populations. Remote sensing appears promising for the monitoring of aphid density in crops. The present research examined the potential use of spectral data to quantify aphid density (greenbug and bird cherry-oat aphid) in 3 winter wheat field experiments and 1 greenhouse experiment. A multispectral ground radiometer and a hyperspectral hand-held spectrometer were used to record reflectance data. In order to quantify the relationship between reflectance data and aphid density, 2 spectral indices were used in regression. The coefficients of determination (r 2 ) ranged from 0.48 to 0.76 for the hyperspectral-derived index and from 0.43 to 0.67 for the multispectral- derived index. The results indicate that multispectral and hyperspectral remote sensing appears functional to monitor aphid population density in production winter wheat fields. Ozet: Buday yaprakbiti, Schizaphis graminum (Rondani) ve yulaf kufl-kiraz› yaprak biti, Rhopalosiphum padi L., buday (Triticum aestivum L.), arpa (Hordeum vulgare L.), supurgedar›s› (Sorghum bicolor L.), yulaf (Avena sativa L.), ve dier tah›llar› dunya cap›nda tahrip eden zararl› yaprak bitleridir. Bu yaprakbitleri istilas›n›n yer ve zaman›n› onceden tahmin etmek mumkun olmamaktad›r. Bu iki yaprak bitlerinden biri olan buday yaprakbiti istilas› onemli urun kayb›na neden olmas›ndan dolay› buyuk meblalarda bocek ilac› buday yaprakbiti younluunu control alt›na almak amac› ile kullan›lmaktad›r. Bundan dolay›, tah›llardaki yaprakbitlerinin younluunu gozlemek icin h›zl› ve tekrarlanbilir bir yonteme gerek duyulmaktad›r. Bu balamda, uzaktan alg›lama uygun bir yontem olarak gorunmektedir. Bu cal›flma da uc buday tarlas›ndan ve bir laboratuvar deneyinden elde edilen tayf verilerinin yaprakbiti younluunu tahmin etme potensiyeli araflt›r›lm›flt›r. Yans›yan ›fl›n portatif spectrometre ve radiometre ile kaydedilmifltir. Yans›yan ›fl›n ile bocek younluu aras›ndaki iliflkiyi olcmek icin iki tane tayf indeksi kullan›lm›flt›r. Tay›n katsay›lar› (r 2 ) hyperspectral indeks icin 0.48'la 0.76 aras›nda ve multispectral indeks icin ise 0.43'la 0.67 aras›nda olduu bulunmufltur. Sonuc hyperspectral ve multispectral uzaktan alg›laman›n budaydaki yaprakbitleri younluunun gozlemlenmesin de etkili bir yontem olduu gorulmufltur.