Spodoptera exigua is one of main pest for horticulture crops. In sustainability agriculture, entomopathogenic like Beauveria bassiana and Metharizium anisopliae are solution to control this pest. This study aimed to examine the compatibility between the entomopathogenic fungus Beauveria bassiana and the vegetable insecticide neem leaf extract against the larvae of Spodoptera exigua. Value LC 50 single testing B. bassiana and neem leaf extract respectively is 0.08% (y=1,65x + 0.16) and 0.627% (y=1,59x-1.02). While the value of LC 50 treatment. combinations B. bassiana with neem leaf extract is 0.079% (y = 1,22x + 1.45). Based on the value of LC 50, it is known that the LC 50 value of the combination treatment is smaller than the LC 50 value of the single treatment, this indicates that the combination treatment has a higher toxicity than the combination treatment in killing S. exigua larvae. The LT 50 values from the LC 50 obtained from the single test of B. bassiana and neem leaf extract were 7.96 days and 6.1 days, respectively. While the value of LT 50 from LC 50 obtained from testing the combination of B. bassiana with neem leaf extract was 5.79 days. Based on the LT 50 value, it can be seen that the LT 50 value of the combination treatment is smaller than the LT 50 value of the single treatment.

Penelitian ini bertujuan untuk menguji kompatibilitas antara cendawan entomopatogen Beauveria bassiana (BB) dan insektisida nabati ekstrak daun mimba (EDM) terhadap larva Spodoptera exigua yang ditinjau dari mortalitas dan nilai toksisitas. Penelitian ini terdiri dari pengujian tunggal BB dan EDM, serta pengujian kombinasi menggunakan Rancangan Acak Lengkap (RAL) 6 perlakuan 4 kali ulangan. Mortalitas larva S.exigua diamati hingga mencapai mortalitas ±90%. Data mortalitas larva diolah dengan analisis probit Finney (1971). Hasil Pengujian tunggal menunjukkan mortalitas perlakuan BB 0,2% dan EDM 5% pada 7 HSP adalah 79,17% dan 91,67%, sedangkan pada 8 HSP sebesar 89,58% dan 95,83%. Mortalitas pengujian kombinasi BB dengan EDM (1:10 w/w) 0,66% pada 7 HSP adalah 91,67%, sedangkan pada 8 HSP 97,92%. Nilai LC50 pengujian tunggal BB pada 7 HSP dan 8 HSP adalah 0,08% (0,06%-0,1%) dan 0,06% (0,05%-0,07%). Nilai LC50 pengujian tunggal EDM pada 7 HSP dan 8 HSP adalah 0,70% (0,54%-0,91%) dan 0,58% (0,45%-0,75%). Nilai LC50 perlakuan kombinasi BB dengan EDM pada 7 HSP dan 8 HSP adalah 0,07% (0,06%-0,10%) dan 0,05% (0,03%-0,06%). Nilai LT50 BB, EDM, dan kombinasinya pada konsentrasi tertinggi sampai konsentrasi terendah berturut-turut 5,20-12,50 hari; 4,68-9,41 hari; dan 4,65-8,28 hari. Kombinasi BB dengan EDM memiliki indeks kombinasi <0,5 yang membuktikan bahwa pengombinasian memberikan efek sinergistik atau kompatibel.   Kata Kunci: Kompatibilitas, Beauveria bassiana, Ekstrak daun mimba, Spodoptera exigua

Spodoptera exigua (Hubner) (Lepidoptera: Noctuidae) is the biggest threat to onion farming, especially in the vegetative phase. In severe attacks, this pest can cause yield losses of up to 100%. Compatibility is one way to increase the efficiency and effectiveness of pest control by using plant-based pesticides or biological agents. Neem Leaf Extract (Azadirachta indica, acronym=NLE) has an azadirachtin compound that can inhibit insect growth, reduce appetite, reproduction, and hatch eggs. The fungus Beauveria bassiana (acronym=Bb) can secrete chitinase, lipase, proteinase enzymes that are able to decompose insect cuticles. NLE was obtained through the extraction method of plant-based pesticides and stored at 4oC until the experiment time. The Bb used was a commercial B. bassiana inoculum in the flour form with a density of 4.5 x 1010 spores/gram (trade name = Natural BVR). To determine the advantages of compatibility, this study is held by a single toxicity test of Bb and NLE, and the combined toxicity test of both. This study used a completely randomized design (CRD) consisting of 6 treatments with 4 replications, each replication used 12 larvae (a total of 48 larvae). Combination toxicity has a higher toxicity than the single use of NLE and Bb. At the LC 95 level, the combination treatment of Bb and NLE was 1.06-1.15 times more toxic than the single treatment of Bb, and 6.87-7.79 times more toxic than the single treatment of NLE. NLE and Bb are considered to have high compatibility (strong synergistic with GI value <0.5). Theoretically, the compatibility of NLE plant-based pesticides and Bb is very promising to replace chemical pesticides that have long-term adverse effects on agroecosystems