Resistance Inheritance of Plutellaxylostella Population to Residual of Emamectin Benzoat

<p>Excessive use of insecticides drives the increasing ability of pests to become resistant. The objectives of this research were to study the susceptibility and the resistance inheritance of the eleven population of P. xylostella to emamectin benzoate. The leaf-dip bioassay was applied to determine the sensitivity of P. xylostella to emamectin benzoate. The offspring of backcrossed F2 were tested whether the resistance was controlled by monogenic. The results showed that the LC50 of the Selo population was 53.42 ppb, and the Puasan population was 212.13 ppb. The genetic analysis showed that the backcrosseddegree of dominance (D) was less than 1. It was indicated that the P. xylostella resistance to emamectin benzoate was recessive. The value of LC50 of the backcrossed F1♀ x ♂S (177.99 ppb) and its reciprocals x ♀R (F1) (201.69 ppb) were not significantly different with the value of LC50 resistance population. This suggests that the nature of P. xylostella resistance to emamectin benzoate was controlled by monogenic.The result of the study would be beneficial for developing strategy to maintain susceptible population using refugee plant during lack of their host.</p>

Resistensi Wereng Batang Cokelat Padi, Nilaparvata lugens Stål terhadap Insektisida di Indonesia

<p>The rice<br />brown planthopper (BPH), Nilaparvata lugens (Stål) is a<br />major insect pest of rice and their infestations occur every<br />year in several locations in Indonesia. The use of<br />insecticides often fails to control the BPH so their<br />populations are still high that cause rice crops show<br />hopperburn and the farmer loses the yields. The<br />development of insecticide resistant in BPH population is<br />one of the factors to contribute to the failure of insecticides<br />control. We have detected the development of field<br />population BPH resistance to BPMC, carbofuran, MIPC, and<br />imidacloprid, but we do not know yet the development of<br />resistance to other insecticides to control BPH in Indonesia.<br />This paper will review several cases on BPH resistance to<br />insecticides in Indonesia and other countries that include<br />aspects of the development of resistance in the field and in<br />the laboratory, the mechanism of resistance, inheritance of<br />resistance, genomics of resistance, and resistance<br />management. A policy and further study is also suggested for<br />insecticide resistance management in Indonesia.</p>

The resistance of cocoa hybrids to vascular-streak dieback

Breeding for VSD resistance on cocoa was carried out by inter-crossing the selected clones of TSH 858, KW 162, KW 163, KW 165, KEE 2, ICS 13 and NIC 7 which were selected based on the criteria of VSD resistance, productivity and cross-compatibility. This research has objective to evaluate hybrids of the crossess for VSD resistance, inheritance of the resistance and selecting the most valuable parental-clones for further crossess. Fourteen hybrids and one control were tested 14 in the randomized-completely block design with 4 blocks where in each plot 16 trees planted at Kaliwining Experimental Station in Jember. The resistance was evaluated in the field by scoring the symptoms in the range of 0—6 at 7 year after planting. The scores were varied significantly among the hybrids in the range of 2.19—4.53. Hybrids which were generated from the crosses of resistant clones performed lower number of the score than the hybrids generated from crosses between two susceptible clones (TSH 858 x NIC 7) which performed highest score. The hybrids classified as resistant were TSH 858 x KW 162 (F1 and reciprocal), KW 162 x KEE 2 (F1 and reciprocal), KW 162 x ICS 13, KW 165 x KEE 2. Of the parental clones, KW 162 is the most promising parent as lower score obtained when used it as male or female compared to KEE 2 which performed quite similar of the score with TSH 858 as susceptible parent. Therefore, it could be supposed that KW 162 has better combining ability than KEE 2 where these resistant-clones showed different segregation of their resistance. The resistance was segregated by KW 162 in term of ratio 15 resistant : 1 susceptible while KEE 2 the ratio 1 resistant: 1 susceptible.Key words: Theobroma cocoa L., hybrid, resistance, vascular-streak dieback.