Biology of Zygogramma Bicolorata Pallister on Parthenium hysterophorus Linn. under Laboratory Conditions

Parthenium hysterophorus Linn. is one of the most aggressive, invasive weeds threatening natural and agricultural ecosystems in the world including Nepal. Augmentative release of host-specific, leaf feeding beetle, Zygogramma bicolorata Pallister (Coleoptera: Chrysomelidae) is one of the sustainable management approaches of parthenium weed. Successful mass rearing program requires knowledge on biology of Z. bicolorata for augmentative release. Thus, life cycle and biology of Z. bicolorata were studied in lab at 26±2 °C temperature and 70±10% relative humidity at NARC, Lalitpur, Nepal during March to September, 2016. The average incubation, larval and pupal periods of the insect were 4.33, 12.20, and 11.00 days, respectively. A single female could lay 1,837 eggs in 58.80 days oviposition period with 73.01% egg hatchability. The insect completed its life cycle in 108.40 and 105.50 days with adult longevity of 91.90 and 75.00 days for females and males, respectively. The average length of egg, pupa, adult female and male was 1.19 mm, 5.90 mm, 6.58 mm and 5.32 mm and breadth 0.51 mm, 3.74 mm, 3.94 mm and 3.20 mm, respectively. The average lengths of the first, second, third and fourth instar larvae were found 1.30 mm, 3.02 mm, 4.96 mm and 8.08 mm and breadth of 0.44 mm, 1.13 mm, 2.02 mm and 3.16 mm, respectively. These findings will help in mass multiplication of Z. bicolorata for biological control of parthenium weed.

Biological Control with Trichogramma in China: History, Present Status, and Perspectives

Trichogramma species make up one of the most commonly used groups of natural enemies for biological control programs worldwide. Given the major successes in using Trichogramma to control economically important lepidopterous pests on agricultural crops in China, the biology and ecology of these wasps have been intensively studied to identify traits that contribute to successful biological control. Since the 1960s, improved mass production of Trichogramma and better augmentative release methods to suppress agricultural pests have been achieved. We review the history of research and development; current knowledge on biodiversity and bio-ecology of the species used; and achievements in mass-rearing methods, release strategies, and current large-scale applications in China. In addition, we discuss potential issues and challenges for Trichogramma research and applications in the future .

Observations on the predatory potential of Lutzia fuscana on Aedes aegypti larvae: implications for biological control (Diptera: Culicidae)

Among the natural predators, larval stages of the mosquito <em>Lutzia fuscana (</em>Wiedemann, 1820) (Diptera: Culicidae) bear potential as a biological control agent of mosquitoes. An estimation of the predatory potential of the larva of <em>L. fuscana</em> against the larva of the dengue vector <em>Aedes aegypti</em> (Linnaeus, 1762) (Diptera: Culicidae) was made to highlight its use in vector management. Laboratory experiments revealed that the larva of<em> L</em>. <em>fuscana</em> consumes 19 to 24 <em>A. aegypti</em> larvae per day, during its tenure as IV instar larva. The consumption of <em>A. aegypti</em> larvae was proportionate to the body length (BL) and body weight (BW) of the predatory larva<em> L. fuscana</em> as depicted through the logistic regressions: y = 1 / (1 + exp(-(-2.09 + 0.35*BL))) and y = 1 / (1 + exp(-(0.4+ 0.06*BW))). While the prey consumption remained comparable among the days, the net weight gained by the <em>L</em>. <em>fuscana</em> larva showed a decreasing trend with the age. On the basis of the results, it is apparent that the larva of the mosquito <em>L. fuscana</em> can be used in the regulation of the mosquito <em>A. aegypti</em> through augmentative release, particularly, in the smaller mosquito larval habitats.

Characterization of the symbiontRickettsiain the mirid bugNesidiocoris tenuis(Reuter) (Heteroptera: Miridae)

Nesidiocoris tenuis(Reuter) (Heteroptera: Miridae) is an omnivorous insect used for biological control. Augmentative release and conservation ofN. tenuishave been used for pest control in tomato crops. Intracellular bacterial symbionts of arthropods are common in nature and have diverse effects on their hosts; in some cases they can dramatically affect biological control. Fingerprinting methods showed that the symbiotic complex associated withN. tenuisincludesWolbachiaandRickettsia. RickettsiaofN. tenuiswas further characterized by sequencing the16S rRNAandgltAbacterial genes, measuring its amount in different developmental stages of the insect by real-time polymerase chain reaction, and localizing the bacteria in the insect's body by fluorescencein situhybridization. TheRickettsiainN. tenuisexhibited 99 and 96% similarity of both sequenced genes toRickettsia belliiandRickettsiareported fromBemisia tabaci, respectively. The highest amount ofRickettsiawas measured in the 5th instar and adult, and the symbionts could be detected in the host gut and ovaries. Although the role played byRickettsiain the biology ofN. tenuisis currently unknown, their high amount in the adults and localization in the gut suggest that they may have a nutritional role in this insect.