The spider mite saga: quest for biorational management strategies

The losses that growers have to absorb due to spider mites can be very discouraging. In spite of the use of acaricides which has understandably been short-term, the loss incurred in the Cameron Highlands ranged between 10-50% annually. The spider mite is quick in overcoming practically all chemicals currently available in the market, thus new compounds have to be used incessantly. Such situations will enhance the potential for the development of genetic resistance. As complete elimination of the spider mite is almost impossible, biological agents can play a significant role in the reduction of mite population, even though they may not function as reliably as chemical pesticides in every situations. Information on the bioecological demographic performance of two indigenous predatory mite species has indicated that they are potentially effective suppressors of spider mite population. A programme of intermittent inundative release sufficiently enhanced by selective acaricide could form the basis for an integrated mite management (IMM) system. Additional microbial control agents in the form of sprayable entomopathogenic fungi indigenous to Malaysia are now available to complement the action of the predators, and can perhaps serve as a plausible alternative to unilateral reliance on chemical acaricides. Hence, an integrated management system to control spider mites can be put in place so that food crops free from pesticide residue can be made available to the consumers

Pupal Distribution of Dacus dorsalis Hendel in Relation to Host Plants and its Pupation Depth

Studies on pupal distribution of Dacus dorsalis Hendel in rdation to host plants and its depth of pupation were conducted. Samples from papaya trees gave significantly (P<O.05) higher pupal count compared to those from guava, starfruit, and jackfruit. No significant differences were obtained among samples from the latie)' three host plants. The pupae were also found to be almost evenly distributed under the trees. The results obtained also showed that this insect prefers to pupate at 2 cm and 3 em soil depth

Pathogenicity of Paecilomyces fumosaroseus (Wise) Brown & Smith, Beauveria bassiana (Bals.) Vuill. and Metarhizium anisopliae (Metsch.) sorokin on the striped flea beetle Phyllotreta striolata F. (Coleoptera: Chrysomelidae)

The ability of three species of entomopathogenic fungi, Paecilomyces fumosoroseus (Wise) Brown & Smith, Beauveria bassiana (Bals.) Vuill. and Metarhizium anisopliae (Metsch.) Sorokin to cause infection on the adults, eggs and larvae of the striped flea beetle Phyllotreta striolata F. was tested. Only one isolate of M. anisopliae and none of the B. bassiana and P. fumosoroseus caused adult mortality in excess of 50% at a concentration of 2 x 107 conidia mL1. One isolate of?, fumosoroseus (Pf), one B. bassiana (Wls) and two of M. anisopliae (MPs and Cy3) were pathogenic to the first instar larvae of P. striolata causing more than 50% mortality at a concentration of 2 x 106 conidia mL1. The rate of larval mortality increased with increase in conidia concentration. The respective estimated LT50 values for Pf, Wls, MPs and Cy3 for the larvae at 2 x 106 conidia mL1 were2.9, 3.5, 3.0 and 3.0 days. The two isolates of M. anisopliae were also highly pathogenic to the eggs causing significant inhibition of hatching, while B. bassiana and P. fumosoroseus were less pathogenic. Estimates of the median lethal concentration for Cy3 and MPs were 13.0 x 105 and 5.03 x 105 conidia mL1 respectively

Spatial pattern of rainfall events:a background study to modeling and forecasting rainfall

The study of extreme rainfall events and their spatial coverage is important in identifying areas with high and low extreme events. It has been widely known that extreme rainfall is responsible for major flash flood and landslide events that have caused significant loss of life and economic losses. Unfortunately, the dynamics of extreme rainfall events still received less concern. This study scrutinized the characteristics of extreme rainfall and their spatial coverage in Peninsular Malaysia using rain gauge data. Eight indices of climate extremes based on daily precipitation data defined and adopted by the Joint Expert Team on Climate Change Detection and Indices (ETCCDI) were calculated. The selected indices captured the precipitation intensity, the frequency and length of heavy rainfall events. The geostatistical method of Ordinary Kriging (OK) is applied to the indices calculated. The results from OK method give a pictorial representation of the structure of extreme rainfall spatial variability which helps in deriving rainfall patterns, quantifying rainfall amounts or help in identifying areas with high risk of extreme rainfall event. This result could provide to researchers and decision makers a case study area that needs adequate attention

Preference of the metallic blue ladybeetle Curinus coeruleus Mulsant for different nymphal instars of Diaphorina citri Kuwayama (Homoptera: Psyllidae)

The preference of the metallic blue ladybeetle, Curinus coeruleus Mulsant for Asian citrus psyllid, Diaphorina citri Kuwayama was investigated in the insectary. The aim was to determine whether there was any preference by C. coeruleus at different stages for different instars of the psyllid D. citri. The 1st and 2nd instar larvae exhibited preference for smaller-sized prey, while the 3rd and 4th instar larvae and adult mostly preferred the 4th and 5th instar nymphs. The highest preference value recorded for each stage of the predator, 1st to 4th instar larvae and adult, were 0.49, 0.29, 0.33, 0.33 and 0.34, respectively on the 1st, 2nd, 4th, 4th and 4th instar nymphs. The probability of capture indicated significant differences among prey instars captured by each stage of predator. The 1st and 2nd instar larvae captured significantly more 1st and 2nd instar nymphs than the other instar nymphs. In contrast, 3rd and 4th instar larvae and adult predator captured significantly more 4th and 5th instar nymphs. Hence, the results suggest that C. coeruleus exhibited body size preference for D. citri nymphs comparable to or slightly smaller than predator's size (stages). This preference was due to the probability of success in capturing the prey

Life table and demographic parameters of the metallic blue ladybeetle, Curinus coeruleus mulsant, fed with the Asian citrus psyllid, Diaphorina citri Kuwayama

Life table parameters were calculated for the blue metallic ladybeetle, Curinus coeruleus Mulsant, fed with the Asian citrus psyllid, Diaphorina citri Kuwayama, at temperatures of 26 - 28° and 75 - 85% RH and natural photoperiod in the insectary of Faculty of Agriculture, Universiti Putra Malaysia. The development of immature stages took 19.1± 0.3 days; mated adult females lived for 34.2 ± 4.7 (range 24-39) days and produced a mean of 80.3 ± 13.6 progeny female-1 during oviposition period of 21.3 ± 1.4 days, with a sex ratio of 1:1.8 (:). The net reproductive rate (R0) was 59.1 and the capacity for increase (rc) was 0.113. The finite rate of increase (λ) was 1.29 female-1 day-1 while the intrinsic rate of natural increase (rm) was 0.116 female-1 day-1. Each female contributed 60.2 individuals to the population in a mean generation time (T) of 35.3 days. , Ibrahim, Y.B., Ibrahim, R. and Osman M.S