Two-sex Life Table Parameters of Pistachio Green Stink-bug, Brachynema signatum Jakovlev (Hemiptera: Pentatomidae)

Pistachio (Pistacia vera L.) is the most important horticultural crop cultivated extensively in central areas of Iran and an economically important nut that ranks the first among the agricultural export commodities in Iran. The annual exportation of this nut crop reaches to 100,000 tonnes that ranks the second after the oil in revenue income of the country. Kerman province is the most important pistachio producing province in Iran. The highest acreage of the pistachio producing lands in this province are allocated to Kaleghochi, Ahmadaghai, Ohadi and Akbari cultivars, respectively. Not to mention that these are the most commonly cultivated pistachio cultivars in Iran. The pistachio trees are attacked by many different insect pests. The pistachio green stink-bug, Brachynema signatum (Hemiptera: Pentatomidae) is a key pest of pistachio in Iran. The adults and nymphs of this insect feed on the developing fruits of pistachio and cause significant damages in the form of pericarp lesions that result to the nut drop. The pistachio green stink-bug is also a vector of thepathogenic fungus, Nematospora coryli Peglion that causes the formation of corky appearance and somewhat bitter and distasteful smell of pistachio endocarp. In the pistachio producing areas of Iran, this pest is present in the pistachio orchards throughout the year and can produce four to five generations per year in Kerman province. Since the host plant can affect the growth, reproduction and survival of herbivorous insects, therefore evaluating the effects of host plant on the growth and reproductive characteristics of insect pest could be used in its integrated pest management programs. These effects could be evaluated by calculating the demographic parameters, especially the intrinsic rate of increase of the insect pest (rm) on preferred host plant, reminded that the demographic parameters are affected by the quality of host plant and are very useful indicators for evaluation the suitability of host plants to insect pests. This research was conducted to study a preferred natural diet (fresh kernels of pistachio) on developmental time, fecundity, survival rate, and life table parameters of pistachio green stink bug, Brachynema signatum (Hemiptera: Pentatomidae). This research was conducted to study a preferred natural diet (fresh kernels of pistachio) on developmental time, fecundity, survival rate, and life table parameters of pistachio green stink bug, Brachynema signatum (Hemiptera: Pentatomidae).

Insects reared on fresh kernels of pistachio head ram species in the growth chamber at 27 ± 1 ˚C, 65 ± 5% RH and a photoperiod 16: 8 h (L: D) and the parameters of age-stage, two sex life table of the insect were determined. The life table study was done with 100 identical eggs of the same age. After hatching, instar nymphs were fed with fresh kernels of pistachio head ram species every day. The data of Life table were analyzed according to the theory age-stage, two sex life table.

The total development time from egg to the death of adults was 83.85 days. The survival rate from newly nymph to adult stages was 34%. Females started to oviposition on day 36, reached its pick on day 44, and then gradually declined until reached zero on day 86 of the insect’s life span. The intrinsic rate of natural increase of population (rm) and the finite rate of population increase (λ) were 0.084 ± 0.0030 and 51.55±0.387 (female/ female/ day) respectively. Gross (GRR) and net reproduction rate (R0) were equal to 140.14 ± 15.17 and 78.78 ± 11.18 female eggs. Mean generation time (T) was 1.088±0.003 days.

The fertility life table can be constructed for analyzing and understanding the effect of external factors and host plants on the growth, survival, reproduction, and intrinsic rate of increase of insect populations. Host plant quality is an effective factor on the fecundity and population growth rate of herbivorous insects. Analysis of age-stage, two-sex life table and its parameters obtained in this study showed that stink bug had an appropriate development on natural diet. These results could help us to understand the B. signatum population dynamics under field conditions. The results could also help us make better management decisions in integrated pest management (IPM) programs for economically important crop, Pistachio.