Factors determining pheromonal trapping of the stem‐borer Chilo partellus (Swinhoe) (Lep., Pyralidae)

Abstract

Certain factors which could affect pheromone trap performance were investigated, in order to develop methods for trapping males of Chilo partellm (Swinhoe), for population monitoring pur oses, using and males, trap attractive range, and trap design, height, inter-trap distance and osition. The twocomponent female sex pheromone (Z-11-hexadecenal and Z-11-hexadecen-1-01) dntified previously from C. partellus female ovipositor washings was not as effective as the virgin female in attractin the males, and hence, caged virgin females were used as lures. Two 1-day-old virgin females attractel the highest number of males; mated females continued to attract males, though in,lesser numbers. Mated males were less attracted to pheromone traps than unmated males. A locally made water trap and a modified Delta trap were e ually effective when baited with two virgin females, and both were significantly more efficient tlan-the sticky traps (Stickydisc, Delta, Phercon 1C and Lund-11) and nonsticky traps (Scentry Heliothis tra and Uni-trap) tested. The range of attraction of the femalebaited trap was more than 40 m. InteArence was seen between traps 20 m apart and also when tra s were placed cross wind and 30 m apart. Water traps or modified Delta tra s baited with two I-day-oyd virgin females set at 0.5-1.0 m from ground level and 40-80 m apart can ge used effectively for monitoring C. partellus populations. female sex attractant. These factors included: pheromone source, age and mating status o P the females IntroductionAmong the various species of stem-borers which severely affect maize and sorghum production, Chilo partellus (Swinhoe) is the most important in Asia and parts of Africa (HARRIS 1989). It is important to have reliable and convenient methods for monitoring its populations, in order to develop suitable control strategies and methods for reducing the losses caused by this insect. Monitoring of C. partellus populations has been mainly based on sampling the immature stages of the pest (egg, larva and pupa) by destructive sampling of the crop. This method is laborious and often can be done only after the pest damage has occurred. Monitoring of the adult populations using pheromone-baited traps, successfully employed in the case of several lepidopterous pests ( KLASSEN et al. 1982;CAMPION 1984;WALL 1984), can be done before the pest inflicts the damage to the crop and could be a more convenient and reliable method, Pheromonal monitoring of the adult populations would allow good timing of the appropriate pest management operations. A pheromonal monitoring system has not been developed for C. partellus, but, two components of the female sex pheromone, 2-1 1-hexadecenal and Z-11-hexadecen-1-01 were identified from the ovipositor washings of virgin females of C. partellus, in India (NESBITT at al. 1979), and the former was found highly attractive to males in field trials.Since then no other study has been reported, and we have, therefore, investigated the factors which could determine the performance of the pheromone trap w...

Population monitoring of Chilo partellus (Swinhoe) (Lepidoptera: Pyralidae) using pheromone traps

“…Details of the trap design and procedure for setting traps were reported in an earlier paper (Unnithan and Saxena, 1990). Two 1-day old virgin female C. partellus, confined to a 3 x 5 cm wire-mesh cage, were used as the source of the sex pheromone.…”

“…The first compound was highly attractive to C. partellus males in field trials conducted in India (Nesbitt et al, 1987). Studies on factors influencing pheromonal trapping of C. partellus using the natural source of pheromone (virgin females) were undertaken and these studies showed that water or sticky traps baited with two 1 day old virgin females were very effective for trapping C. partellus males (Unnithan and Saxena, 1990). Studies on factors influencing pheromonal trapping of C. partellus using the natural source of pheromone (virgin females) were undertaken and these studies showed that water or sticky traps baited with two 1 day old virgin females were very effective for trapping C. partellus males (Unnithan and Saxena, 1990).…”