JWSS - Journal of Water and Soil Science

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The host-stage preferences of alfalfa black aphid, Aphis craccivora, by parasitoid wasp, Lysiphlebus fabarum, were studied under two trials under growth chamber conditions (55±5 %, R. H., L:D 14:10 H. and Tem. 20 ±2^° C ). In the first trial, all stages of aphid in equal ratios, and in the second trial, variable ratios of 5:15, 15:15 and 15:5 of 3rd and 4th instar nymphs were used for parasitisation. The objective was to identify the most preferred stage of aphid for parasitism by Lysiphlebus fabarum. The results showed that 3^rd instar nymphs of alfalfa black aphid were the most preferred stage with 38.75% of parasitism. Whereas 4^th instar nymphs and adults had 23.75% and 21.25% parasitism, respectively. The first instar nymphs were not parasitized at all. In the second trial with variable ratios of 3^rd and 4^th instars of alfalfa black aphid, parasitism of 3rd instar in ratios 25, 50 and 75 percent of total population were 35.9, 55.74 and 79.6%, respectively, while those for 4^th instar nymphs were 20.36, 44.26 and 64.09%, respectively. So there was a positive preference for 3^rd instar and a negative preference for 4th instar nymphs.

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Elm leaf beetle, Xanthogaleruca luteola (Müller), life and fertility tables were investigated under laboratory conditions (25±2°C, 70±5%R.H. and 16L: 8D), on Ulmus carpinifolia, U.c.var.umbraculifera, U. glabra var. pendula and Celtis caucasica, in spring and summer. Since the experiments were conducted under controlled conditions, feeding on hosts with different nutritional qualities was considered to be the only cause of mortality. The aim of this study was to determine the susceptible hosts to the pest. The initial population for each life table was 100 first larval instar on 20 cm foliage which continued to the end of adult longevity. For larval and adult feeding, the foliage was replaced regularly. Larval and adult mortality and eggs number per female were recorded on a daily basis. Results showed that the net reproductive rate (R₀) and intrinsic rate of increase (r_m) were higher on U. carpinifolia than the other hosts in both seasons. The net reproductive rate was less than one on Celtis caucasica in spring and on U. c. var. umbraculifera in summer, which represented the negative population growth on these hosts. Therefore, U. carpinifolia was the most susceptible host to Elm leaf beetle, the other susceptible hosts being U. glabra var. pendula and U. c. var. umbraculifera, in a descending order and Celtis caucasica was the least susceptible one. .

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The biological and behavioural parameters of Anisopteromalus calandrae (Hym.: Pteromalidae), a parasitoid of Callosobruchus maculatus (Col.: Bruchidae) on Chickpea were studied in laboratory conditions at temperature of 25±1ºC, photoperiod 16:8 (L:D) and 20±5 % RH. The pre-adult period of the wasp was 19.82 ± 0.038 days and pre-ovipositional period in this wasp was so short that female laid eggs immediately after emergence. Reproductive and post reproductive periods were 25.12 ± 1.98 and 1.75 ± 0.28 days, respectively. Adult life span was 26.69 ± 1.98 days. Total number of progeny produced by a female was 240 ± 28.51. The sex ratio (% females) of the resulting adults on hosts was 0.49. The functional response of A. calandrae was type II. The host stage preference by the parasitoid was investigated in two methods, choice and non-choice experiments. In the first condition, the parasitoid preferred the 4^th larval instar to others, but in the second, it preferred both 4^th larval instar and pupae. Adult longevity for both female and male parasitoids provided with honey solution (% 50), host larvae, host larvae and honey solution (%50), and finally without host larvae and honey solution was 49.00 ± 4.32 , 26.69 ± 1.98, 38.90 ± 3.52 and 5.66 ± 0.37 days for females and 10.64 ± 1.5, 6.85 ± 0.34, 8.41 ± 0.52 and 5.59 ± 0.28 days for males, respectively.