Efficiency of Acerophagus papayae on different host stage combinations of papaya mealybug, Paracoccus marginatus

Acerophagus papayae is a koinobiont endoparasitoid of the invasive papaya mealybug, Paracoccus marginatus and has been introduced as a classical bio-control agent of the mealybug in many countries. Considering the importance, parasitism efficiency of A. papayae against various life stages of P. marginatus was conducted in choice experiments. Results suggested that A. papayae showed higher parasitism efficiency towards third instar female nymphs and adult female P. marginatus in comparison to second instar male. However, second instar male nymphs were more preferred in comparison to second instar female nymphs. Acerophagus papayae exhibited a highly significant sex-biased development ratio as a female dominant progeny emerged while feeding on female hosts and vice versa. No difference was recorded in the developmental time of male and female A. papayae, however, females matured one day later than males. The only gregarious behaviour of A. papayae was recorded on adult female P. marginatus as more than one adult parassitoid emerged from a single host. Study results suggested that A. papayae has a tremendous potential to be utilized in classical biological control programs against P. marginatus as it showed more preference towards female hosts; hence not only reducing available pest population but also will affect the pest population of next generation

Life table, infestation and interaction of papaya mealbug Paracoccus marginatus Williams & Granara de Willink (Pseudococcidae: Hemiptera) and its parasitoids

The papaya mealybug, Paracoccus marginatus Williams and Granara de Willink (Hemiptera: Pseudococcidae) is a serious pest of papaya. This exotic pest cause a serious problem if, indigenous natural enemies are not available. This pest was never studied in Malaysia although severe infestation of this unidentified mealybug was reported by papaya farmers. This study therefore, was initiated to investigate the life table of papaya mealybug, Paracoccus marginatus (Hemiptera: Pseudococcidae), its infestation and interaction with natural enemies. Life table study of P. marginatus was initiated on four cohorts, each consisting of 137, 120, 102 and 100 eggs. Agespecific survival life table indicated that 64.27% P. marginatus eggs successfully reached to adults with a sex ratio of 1.09:1 (Female: Male). The pattern of survivorship curves (lx) falls in type III indicating highest mortality in offsprings. The highest mortality was recorded in first instar nymphs (20.09%) with k-value of 0.097. Age-specific fecundity (mx) of P. marginatus showed earliest egg laying on day 25 and continued till death of female. The last female died on day 47. The female laid on average 275.91±8.10 eggs. The maximum (74.90%) eggs laid were during 27th to 33rd day. The intrinsic rate of natural increase (rm) of P. marginatus was 0.12 per female per day and the daily finite rate of increase (λ) was 1.13 female offsprings per female per day with mean generation time (Tc) of 30.72 days. The net reproductive rate (R0) was 43.36 female offsprings per female. Doubling time was recorded as only 5.65 days. Survey for infestation of P. marginatus was done in two states, namely Negeri Sembilan and Selangor, to confirm the pest status in Peninsular Malaysia. A total of ten locations were surveyed for the infestation. All aerial plant parts of the papaya plants including leaves, fruits and stem were observed because pest attacks only aerial plant parts except roots. Results indicate that the pest infestation was observed in both states. This pest was also found infesting seven other host plants (Hibiscus, Cassava, Plumeria, Roselle, Eggplant, Jatropha and Broad beans). During observation, two predators, Apertochrysa sp. and Cryptolaemus montrouzieri and, one primary parasitoid, Acerophagus papayae and three secondary parasitoids viz. Chartocerus sp., Marietta leopardina and Cheiloneurus sp. were found on P. marginatus. Out of 7965 mummies of P. marginatus collected, A. papayae showed higher (95.22%) population frequency. However, secondary parasitoids remained lower than 5%. The study on weekly population fluctuation of P. marginatus and its natural enemies on papaya in five locations within vicinity of Universiti Putra Malaysia showed the highest mean P. marginatus population (7.02 per 25 cm2 leaf area) in Sri Serdang. The maximum population of P. marginatus was found on the basal part of papaya leaf compared to middle and apical leaf parts. The population of Apertochrysa sp. on papaya was comparatively higher (0.48 per 25 cm2 leaf area) in Ladang-2. The population of C. montrouzieri ranged between 0.33 to 0.54 per 25 cm2 leaf area. The A. papayae population was higher (1.36 to 2.00 per 25 cm2 leaf area) at Faculty of Agriculture (old), Ladang-2, Bukit Expo and Sri Serdang. The population of P. marginatus remained higher in the month of August, thereafter, declined due to appearance of natural enemies. Similarly, the population of predators (Apertochrysa sp. and C. montrouzieri) and parasitoid (A. papayae) was high during August and declining in the following months. Among the weather parameters, only temperature showed significant effect on the population fluctuation of P. marginatus, whereas significant effect of two predators, C. montrouzieri and Apertochrysa sp. and a parasitoid, A. papayae was observed on the P. marginatus population. Studies on A. papayae was conducted on different host stages of P. marginatus viz. second instar male, second instar female, third instar female and adult female in choice and no-choice situations. All the treatments were replicated ten times. The highest percent parasitism was recorded in second instar female (59±5.66%) in no choice situation. However, in choice situation no specific trend of parasitism was found. In choice and no choice situations, the male-biased sex ratio was observed in second instar male P. marginatus and the female-biased sex ratios in all female stages of P. marginatus with longer developmental time in females. Interestingly, A. papayae showed gregarious behavior in adult female P. marginatus while solitary in rest of instars in both choice and no choice experiments

Parasitism, sex ratio, developmental time and gregariousness of Acerophagus papayae (Hymenoptera: encyrtidae) on male and female host stages of Paracoccus marginatus in no-choice situations

Acerophagus papayae, accidentally introduced parasitoid of Paracoccus marginatusin Malaysia was studied for parasitism, sex ratio, developmental time and gregariousness behaviour. The parasitoid was able to develop in all stages of P. Marginatus except first instars, prepupaand pupa. The maximum parasitism (59.0±5.66%) was observed in second instar female nymph and minimum (39.0±3.48%) in adult female P. marginatus. In adult female, the A. Papayae showed gregariousness behaviour (2.87 individuals per host). Male biased sex ratio (69.14 ± 3.37%) was observed in second instar male and female biased sex ratio (71.76± 4.21% and 71.53 ± 4.33%) was observed in third instar female nymph and adult female P. Marginatus respectively. The minimum and maximum developmental time for male A. papayae(13.00 and 13.89 days) was found in second instar female nymph and adult female P. Marginatus respectively. However, minimum and maximum developmental time for female A. papayae(13.85 and 14.42 days) was found in second instar male nymph and third instar female nymph of P. marginatus. The parasitoid showed gregarious behaviour (2.87 individuals per host) only in adult female P. marginatus. This vital information can be used in evaluating the efficiency of parasitoid

Life table and demographic parameters of papaya mealybug, Paracoccus marginatus (hemiptera: pseudococcidae) on Hibiscus rosa-chinensis

The papaya mealybug Paracoccus marginatus is an imperative insect pest because of its invasive and polyphagous nature. Age-specific life and fertility tables of P. marginatus were constructed in laboratory conditions (27±2 °C, 60±5% RH). Survival and fertility characteristics of P. marginatus were observed on basis of provision of unlimited food source (Fresh hibiscus leaves) with pesticide and natural enemy free environment. The highest apparent mortality (20.1%) was observed in the 1st instar nymphs with k-value of .097 indicating the key factor in regulating pest population size. The proportion of female to male was 1.09:1. The values for net reproductive rate (Ro), mean generation time (Tc), intrinsic rate of increase (rc), innate capacity of increase (rm), finite rate of increase (λ), and doubling time were recorded as 43.36 female offsprings per female, 30.73 days, 0.1248/day, 0.1227/day, 1.1329 female offsprings/female and 5.65 days respectively. These results will play vital role in development of reliable and sustainable IPM strategy for the pest

The vespid fauna of Pakistan

Rafi, Muhammad Ather, Carpenter Muhammad Qasim, James M., Shehzad, Anjum, Zia, Ahmed, Khan, Muhammad Rafique, Mastoi, Muhammad Ishaque, Naz, Falak, Ilyas, Muhammad, Shah, Mazafar, Bhatti, Abdul Rauf (2017): The vespid fauna of Pakistan. Zootaxa 4362 (1): 1-28, DOI: https://doi.org/10.11646/zootaxa.4362.1.

Screening of Different Varieties of Okra (Abelmoschus esculentus L.) against Sucking Insect Pests

The screening of different varieties is one of the key strategies used in Integrated Pest Management to control the insect population and to escape the use of synthetic insecticides. This study was aimed to screen different okra varieties against sucking insect pest complex such as thrip, jassid, aphid, whitefly and mealybug. The experiment was conducted at Agriculture Research Institute Tandojam. The varieties such as Rama Krishna, Silky-460 and Bharat Kawairi were cultivated in RCBD layout and each treatment was replicated five times. The results revealed that the most infested variety was Bharat Kaiwari followed by Silky-460 and Rama Krishna throughout the experimental period. The highest mean population of the sucking insect pests (thrip, jassid, aphid, whitefly and mealybug) was 9.61±0.35, 3.22±0.13, 18.33±0.50, 3.25±0.15 and 3.75±0.19 respectively was observed on Bharat Kaiwari and the lowered on Rama Krishna. However, the attack of aphid was prominent on all okra varieties and overall pest attack was higher in the month of June. Similarly, the co-efficient correlation analysis showed a positive relationship of temperature and humidity (r= 0.012; r = 0.128) with thrip population whereas there was a negative relationship between temperature and humidity with remaining sucking pests. Both jassid and mealybug population indicated a significant difference with temperature. Similarly, relative humidity displayed a significant impact on population of mealybug (r = 0.365) and aphid (r = -0.096). Thus, it could be concluded based on the results that Rama Krishna is the most resistance against sucking insect pests as compared to Silky-460 and Bharat Kaiwairi